Research Peter Aerts

Abstract

Throughout the long evolutionary history of tetrapods, multiple taxa returned to life in water from a terrestrial (or aerial) environment. Notable groups are Mesozoic marine reptiles, sirenians, and whales. Among mammals, aquatic taxa within the order Carnivora, or "meat-eaters", show an 'incomplete' transition to life in the aquatic environment: pinnipeds (true seals, sea lions, fur seals and walruses), otters, polar bears, and even the fishing cat rely heavily on water for feeding, but none are exclusively aquatic and they all still return to land to rest, give birth, etc. The transition from a terrestrial to a (semi-)aquatic lifestyle is an impactful biological shift, with multiple potential drivers and requires various physiological and anatomical adaptations. As this transition occurred independently in several carnivoran groups (Pinnipedia, Mustelidae, Ursidae, Felidae), as well as in different environments (riverine, lacustrine, and marine), it asks the following questions: Which environmental and ecological changes triggered this transition for each group? How did these carnivorans functionally adapt to life in water? What are the similarities and differences between these groups, and between aquatic carnivorans and other aquatic mammals? And, more specifically, what is the extent of morphological and functional convergence between these lineages? The MEATLOAF project aims to investigate the different evolutionary aspects of this transition in carnivorans from land to water, specifically targeting adaptations for locomotion (on land and in the water) and feeding (prey sensing, prey capture, and food processing, both above and below the water surface), using a variety of well-supported proxies. Proxies will be organized along two main approaches, which will link to one another in a two-way process: (1) a comparative approach, documenting the morphological diversity and shifts in morphology, and (2) a modelling approach, focusing on performance and loading of the recorded morphologies. Comparative aspects will include anatomical, systematic and phylogenetic analyses, all gathered in a 'classical paleontology' work package, as well as geometric morphometric and microanatomical-osteohistological packages to quantify internal and external morphology. The modelling approach will encompass functional analyses, finite element analyses, computational fluid dynamics, and musculo-skeletal modelling, each within its own work package. A synthesis of the results of these different packages will ultimately result in a time-calibrated assessment of the paleoecological and paleoenvironmental frameworks in which these groups evolved to life in water, in order to better understand the biotic and abiotic drivers of such a major, iterative transition.

Researcher(s)

• Promoter: Van Wassenbergh Sam
• Co-promoter: Aerts Peter
• Co-promoter: Van Damme Raoul
• Fellow: Dewaele Leonard

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Nature provides an almost inexhaustible source of inspiration for innovative designs that may help to tackle many of the world's current social, economic and environmental challenges. In accordance, the potential of bioinspiration (including biomimetics and biomimicry) has become widely recognized in academia and industry. The main hurdle preventing the field of bioinspiration from delivering its promises, however, stems from differences in tools, practices and viewpoints of its practitioners, often obstructing further development towards successful products. Nature4Nature, a unique joint effort of biologists, engineers, designers and manufacturers, will immerse young doctoral researchers (DCs) in a learning environment that fully spans the inspiration, integration and implementation aspects of bioinspired design to tackle the conceptual, methodological and practical challenges. It will provide DCs (a) with a mindset and know-how to harness biodiversity into design; (b) with the theoretical background and practical skills for transferring biological model systems into engineering designs and applications; and (c) with an attitude and competence to implement bioinspired ideas in an explicit sustainable way. Nature4Nature will focus its research activities onto one model system: how to efficiently separate solid particles from liquids. Biological filtration systems have evolved repeatedly over the earth's living history. Nature4Nature will teach DCs to make the most of this rich heritage, using it as an inspiratory source for designing and manufacturing high-throughput, clog-resisting filtering systems that can help conserving and restoring the world's aquatic habitats. By fostering a new generation of researchers operating at the interface between scientific disciplines, sectors and societal actors, Nature4Nature sets out to spur innovative practices and will aid in overcoming the barriers to implementation of bioinspiration in the design process.

Researcher(s)

• Promoter: Du Bois Els
• Co-promoter: Aerts Peter
• Co-promoter: Broeckhoven Chris
• Co-promoter: Van Damme Raoul
• Co-promoter: Van Wassenbergh Sam
• Co-promoter: Watts Regan
• Fellow: Hageneder Lukas
• Fellow: Krsteska Katerina

Research team(s)

• Product development

Project website

Project type(s)

• Research Project

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This core facility integrates top quality infrastructure and unique expertise in X-ray imaging for the reconstruction, processing and analysis of dynamic 3D scenes. It utilizes complementary platforms for 4D X-ray imaging, including an ultra-flexible and multi-modal X-ray CT system (FleXCT) and a stereoscopic high-speed X-ray videography system (3D2YMOX). The facility offers customized services for image acquisition-reconstruction and analysis for both industrial and (in-vivo) biological studies.

Researcher(s)

• Promoter: Sijbers Jan
• Co-promoter: Aerts Peter
• Co-promoter: De Beenhouwer Jan
• Co-promoter: Dirckx Joris
• Co-promoter: Van Wassenbergh Sam

Research team(s)

• Vision lab

Project type(s)

• Research Project

Abstract

Horses are one of the most recognisable mammals alive today, yet they have undergone dramatic changes throughout their evolution. In particular, the forelimb has changed from an ancestral, four-toed horse to the modern one-toed species we know today. To understand the story of the horse limb, we must look at them with respect to other members of the order Perissodactyla. For example, tapirs are living relatives of horses which retain four toes on their forelimbs, similar to extinct horse ancestors. Tapirs and horses therefore represent two polar forelimb morphologies within perissodactyls, from which an investigation into the transition from four-to-one digit in horses can be launched. Modern horses have lost three of their forelimb digits, leaving them with a single digit; however, extinct three-toed horses occurred alongside one-toed horses for many millions of years. The proposed project will use multi-body modelling to compare functionality of the forelimb toes throughout horse evolution, using detailed muscular inputs from modern species. Static musculoskeletal models for the forelimbs of four-, three- and one-toed perissodactyls will be constructed. Once optimised to minimise the muscular outputs, the models will be tested to see which digits are involved in locomotion. This approach represents a first attempt to simulate extinct horse locomotion using musculoskeletal modelling, enabling the inspection of horse limb evolution across a macroevolutionary landscape.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Maclaren Jamie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In granivorous songbirds, feeding performance is a major driver in the evolution of beak morphology. This is illustrated by several classical works relating beak shape to feeding ecology (e.g., in Darwin's finches). However, beak shape alone fails to provide comprehensive explanations for functional trade-offs between specific aspects of feeding performance, in particular those involving beak movement to handle seeds. We lack quantitative data on how the cranial system generates controlled three-dimensional movement of the upper and lower beak during the processing of seeds. To achieve a better understanding of the mechanics of granivory, I will investigate the musculoskeletal mechanics of the cranium during grasping, positioning, and dehusking of seeds in three species of granivorous songbirds that vary in beak shape and bite strength. Both experimental and computational approaches will be used, including high speed imaging, biplanar x-ray videography, mechanical testing of muscle and ligament properties, and multi-body musculoskeletal modeling. This study will provide unprecedented insight into the kinematics and dynamics of the cranial system. My findings will help to bridge fundamental knowledge gaps on avian cranial function, and also provide the biomechanical basis for understanding the relations between beak movement performance and evolution in songbirds.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Van Wassenbergh Sam
• Fellow: Mielke Maja

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

To generate movement, muscles contract, and by doing so change shape. While such shape changes are obvious and intrinsic to force generation, we know little about their functional role. Since muscle forces remain difficult (often impossible) to be measured in vivo, understanding the precise link between muscle shape changes and muscle forces will thus have an important fundamental and, ultimately, also applied scientific impact. For this purpose, advancing methodologies to measure 3Dmuscle shape changes during contraction is required. In I-MUSCLE, I propose to first advance innovative techniques to measure whole muscle shape changes during contractions, and secondly, to use these advancements to answer key questions about 3D muscle shape changes and their role in force production. I will take an in situ approach to study the calf muscle of guinea fowl. I will measure muscle shape changes by using ultrafast computed tomography (< 2s) and high-speed stereo X-ray videography (up to 750Hz), while also recording muscle forces. The muscle will be stimulated electrically to induce various contraction states. Gaining a better understanding of how muscles change shape under realistic conditions and how these shape changes are linked to muscle force generation is critical for gaining innovative neuromechanical and -physiological insights in muscle function. Ultimately, this may lead to practical applications such as bio-inspired robotics and improved rehabilitation procedures.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Aeles Jeroen

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

A global increase in lethal fungal infections of both animals and plants threatens biodiversity. Therefore, research on how organisms defend themselves against newly emerging diseases is extremely relevant and the timing critical. In recent years, North American snake populations have experienced elevated numbers of cases of Snake Fungal Disease (SFD). This disease, evoked by the fungus Ophidiomyces ophiodiicola (Oo), is spreading from the east to the west of the United States of America. As an animal's skin is the first barrier against infectious disease, skin chemicals may suppress the growth of harmful microbiota. However, the antimicrobial properties of the skin chemicals of snakes, and reptiles in general, has never been assessed. The current project aims to 1) investigate whether snake-skin derived molecules have repellent properties against fungi and bacteria, 2) what the chemical nature of these disease-suppressing agents is, and 3) whether these form effective natural defenses against SFD. The relevance of this project's results reaches beyond U.S. borders as the international trade in reptiles as pets and zoo animals may significantly facilitate the spread of SFD.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Van Moorleghem Charlotte

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Balance is crucial during locomotion, and the challenges are largest in fast, agile and/or manoeuvrable animals. The vestibular system in the inner ear plays an important role in balance by sensing head movements. A popular line of research investigates anatomical adaptations of the vestibular system for enhanced sensitivity in agile animals. Yet, the actual effect of the observed anatomical features on sensitivity remains largely speculative. This project bridges all functional steps from vestibular anatomy to locomotor performance. First, I will quantify the effect of the anatomical differences on the vestibular sensitivity. The vestibular sense is used to stabilise the head during locomotion, so in a next step, I will test how increased vestibular sensitivity enhances head stabilisation in an experimental setup. Finally, I will assess whether a superior head stabilisation improves the locomotion performance and balance on runways of different levels of complexity. Because the balance requirements depend on the habitat complexity, locomotion style, and anatomy, this project takes an ecomorphological, comparative approach. By comparing lizard species that differ substantially in size, habitat, and agility, I will be able to assess the balance strategies of animals with different ecologies.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Goyens Jana
• Fellow: Jorissen Cas

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Osteoarthritis (OA) is a disease of the whole joint, with a progressive deterioration of cartilage and subchondral bone. Altered mechanical loading is widely accepted, but poorly understood as a driver of OA. Bone and cartilage are mechano-adaptive tissues. It has been assumed that changes in structural and material properties in either tissue caused by altered load distribution, drive mechano-adaptive response adaptations in the other tissue. This is called mechanical crosstalk in the bone-cartilage unit. Animal experiments alone are not sufficient to elucidate dynamic mechanical crosstalk in OA. Our project aims to assess how mechano-adaptive interactions between bone and cartilage contribute to OA development. Our innovative approach relies on an adaptive, multi-scale computational modeling framework that relates estimates of joint loading (organ scale) to tissue loading (tissue scale), and dynamically adapt bone and cartilage based on local mechanical stimuli (adaptive model). First, we will assess knee loading in rats with destabilization of the medial meniscus (DMM) with multibody dynamics. Second, we will develop a multi-scale, adaptive model of the rat knee using finite element analysis, relating tissue mechanical cues to bone and cartilage mechano-regulatory algorithms, to predict joint adaptation in rats with DMM. Third, we will use this model to predict joint adaptation when either bone resorption or cartilage degeneration is reduced.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

According the concept neuromechanics, a large part of motor control is embedded in the morphology of the movement apparatus. The additional neurological steering is (evolutionary) tuned to optimally exploit the intrinsic morph-dynamical characteristics of this apparatus. Understanding this interaction requires (i) good knowledge of the state of the art of motor control (its neurophysiological basis as well as from the control-theory point of view), and (ii) acquisition of skills and expertise to apply optimization simulation using forward musculo-skeletal dynamical modelling (i.e. the most important tool for neuromechanical research). By being able to immerse myself continuously and sufficiently long in both study aspects I will be able to give a new and necessary turn to my research on the evolution and function of musculo-skeletal systems.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Natural selection has bestowed animals with a multiplicity of morphological, physiological and behavioural adaptations to cope with the challenges imposed by the environment. Since, this happens at the evolutionary time scale (over generations), many species additionally evolved plasticity to buffer 'within lifetime-changes' in their environment. Sensory-motor-flexibility helps animals overcoming unpredictable perturbations in real time. In many animals, locomotion is essential for foraging, predator escape and mate finding strategies. Hence, natural selection undoubtedly optimizes locomotor performance (e.g. manoeuvrability, stability, efficiency,…) to meet the species' specific ecological requirements. This optimization is likely to include elements enabling animals to respond to environmental changes at different time scales. Appreciating the value of animals as a source of inspiration, robotics focused for a long time primarily on long-term locomotor adaptation to stable environments (e.g. terrestrial versus aquatic, climbing versus level locomotion). Only recently, engineers also became interested in the remarkable versatility of animals – the way in which they almost effortlessly adjust their locomotion in response to changes in external (e.g. substrate, medium) or internal (e.g. limb loss or impairment, loading) conditions. In sharp contrast to animals, robots appear limited, rigid, vulnerable to damage and hence at mercy of unexpected perturbations. With this SEP-allowance, we initiate (first term PhD-grant) a study on the functional morphology and neuromechanics of lacertid lizard locomotion. Despites the rather uniform overall body-build of this taxon, members evolved subtle morphological differences (e.g. toe lengths, claw shapes, relative trunk length, etc.) in response to drastically different habitats. Locomotor kinematics and dynamics of specimens forced to run in, for them, unnatural environmental conditions and when imposed to sudden shape perturbations by bracing limb joints will be studied. To gain insights in the flexibility of the motor-system and -strategies employed to deal with the new environments and (shape) perturbations, results will be compared with the kinematics and dynamics of unrestrained locomotion in 'natural' environments. Comparing these results between eco-types must elucidate which morphological intricacies stand for the highest behavioural plasticity. These insights must be transferred to AI-researchers and roboticists aiming at the development of flexible machines (in terms of morphology, sensory-motor systems and controllers) able to adjust, on the fly, their behaviour and eventually their morphology to new circumstances. Ab initio, we will collaborate with Prof. S. Rissi (REAL-lab at IT University, Copenhagen). Together, we will explore opportunities for further funding and for expanding the network towards the development of new technologies. Briefly, anticipated steps towards valorisation are: - optimize simulated (simplified) robotic systems to identify (a) criteria that determine similar motoric strategies to cope with new environments or perturbations and (b) the effect of subtle morphological differences on the simulated performance [1]; - re-interpret the outcome of the biological experiments based on simulation results [2]; - development a physical prototype that adjust its behaviour, eventually morphology, according the needs, based on results of [1] and [2]; - test the prototype as in 'lizard'-experiments: the sensory-motor-control should provide new strategies, eventually new morphologies, in previously unknown conditions [proof of concept]. Ultimately, principles and concepts of this prototype should be transferred to autonomous legged robots built for exploration or rescue tasks, or to prosthetic devices that adjust automatically according to the locomotor tasks (e.g. level, climbing, descending, etc.) and terrain conditions (e.g. dry, slippery, etc.).

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

According the concept of neuromechanics, a large part of motor control is embedded in the morphology of the movement apparatus. The additional neurological steering is (evolutionary) tuned to optimally exploit the intrinsic morph-dynamical characteristics of this apparatus. Understanding this interaction requires (i) good knowledge of the state of the art of motor control (its neurophysiological basis as well as from the control-theory point of view), and (ii) acquisition of skills and expertise to apply optimization simulation using forward musculo-skeletal dynamical modelling (i.e. the most important tool for neuromechanical research). By being able to immerse myself continuously and sufficiently long in both study aspects I will be able to give a new and necessary turn to my research on the evolution and function of musculo-skeletal systems.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Lacertid lizard species show a remarkable diversity in locomotion behaviours. Depending on their habitat and ecology, some species move in a highly dynamical and fast manner, while others are characterised by slow movements. Thus, their locomotion behaviours most likely pose different demands on their balance control. The 3 semi-circular (SC) canals of the vestibular system are crucial in this regard, because they sense angular accelerations of the head. Hence, we hypothesise that the vestibular system is adapted to species-specific locomotion behaviour. We will perform a comparative study of the geometrical and functional properties of the SC canals of Lacertidae. Usually, the bony SC walls are investigated, but we will focus on the membranous walls because these determine the vestibular system mechanics. To facilitate future studies, we will compare the geometry of the bony and the membranous morphology, and study the functional consequences. The membranous SC canals are filled with endolymph fluid that deforms a cupula and its sensors when accelerated angularly. We will investigate the fluid dynamical properties of the 3 interconnected SC canals with a Fluid-Structure Interaction model. We will thoroughly examine the functional consequences of the geometry (i.e. anatomy) and in vivo excitation (i.e. behaviour) on sensitivity and response time in lacertid lizards. This will facilitate future comparative studies, which are currently unequivocal in this regard.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Goyens Jana

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Through millions of years of evolution, nature has unfolded an array of armour types in the animal kingdom. The underlying mechanisms of natural body armour have received considerable attention in the field of biomimetics because of their potential role in serving as inspiration for artificial protective materials. Unfortunately, the majority of biomimetic studies often unambiguously assume that nature has selected the most optimal designs. Instead, the response of traits to natural selection is subject to various constrains including functional trade-offs. Hence, the current biomimetics approach might fail to fulfill the requisites of a well-designed biomimetics study and indirectly constrain the development of artificial body armour. The proposed project employs a strong ecological and evolutionary framework to investigate the effect of functional trade-offs on the evolution of body armour. Cordyline lizards are the ideal study system for a comparative and experimental analysis of body armour, because unlike other vertebrates, they display a vast amount of variation in the expression and morphology of osteoderms (i.e. body plates embedded in the skin). The study integrates evolutionary biology and functional morphology with the field of biomechanics while benefiting from state-of-the-art technology such as high-resolution micro-computed tomography scanning, 3D bioprinting and novel simulation software to ultimate put the current approach of biomimetic studies to the test.

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Fellow: Broeckhoven Chris

Research team(s)

• Functional Morphology

Project website

Project type(s)

• Research Project

Abstract

Advances in antenatal medicine and neonatal intensive care have resulted in improved survival of human infants born with a low birth weight and at the limits of viability, but not in the reductions of motor deficits. Locomotor skills are essential for participation in all daily activities and therefore are paradigmatic for insights in motor development in general. Longitudinal experimental designs studying locomotion are needed to elucidate the contributions of intra-uterine growth restricted development of the musculoskeletal and the nervous system onto the motor deficits. Such fundamental longitudinal experiments are ethically controversial in human infants, necessitating appropriate animal models for research. In modern sows, piglets born with a low birth weight and low viability frequently occur. These piglets show characteristics of underdevelopment similar as those seen in human infants with a low birth weight and viability. This, together with their high physiological resemblance, makes the pig an ideal model to study the development of growth-impaired locomotion. This project characterizes and compares the longitudinal development of locomotion in the normal and low birth weight piglet. To this purpose we make use of 4D-morphology, dynamic mechanical modelling and functional morphological analyses (cfr. the concept of neuromechanics). This requires the technological development of rapid 3D dual energy tomography (including soft tissue reconstructions) integrated in the existing 3D²YMOX-platform (biplane X-ray). Differences in both coordination and control will be linked to changes at the level of the musculoskeletal, as well as the neurological components of the locomotor system.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Co-promoter: Sijbers Jan
• Co-promoter: Van Ginneken Chris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Lameness is the most common reason that horses present to veterinarians. The economic cost of lameness in horses in the United States was estimated to be $ 678 million in 1998 and a UK survey estimated lameness incidence at 19%. Comparable economic data for Europe are lacking but the cost is likely of similar magnitude. An early diagnosis is critical in the treatment of equine lameness, as it greatly improves the chances of a full recovery. Unfortunately, early detection is difficult due to the limits of the human eye, even for experienced professionals. Over the last few decades, attempts have been made to assist the clinician by quantifying lameness objectively using kinematics from motion capture systems, kinetics from force plates beneath the hooves, or inertial sensors mounted on the horse in different configurations. Force plate analysis is considered the gold standard in diagnosis of equine lameness but this approach is costly, not mobile and typically inaccessible to horse owners and veterinarians. Moreover, the current objective methods rely heavily on the assumption of symmetry. This assumption can be violated when horses are bilaterally lame or when sound horses show a degree of asymmetry due to conformation. In addition, the repeatability of the symmetry index has been questioned. To better maintain the health and fitness of sport horses, a more cost-effective modality is needed for early detection of preclinical lameness. We plan to develop a fully automated measurement system that is affordable for the stable owner and that will help the owner seek veterinary assistance before a potential lameness progresses. As experienced biomechanists with technical expertise, my research group maintains ongoing collaborations with the veterinary field and are uniquely positioned to tackle the problem of detecting equine lameness. We have always been at the forefront of foot pressure measurements in animal locomotion research and have established key relationships with RSscan and the CRC. Because the problem of equine lameness requires an in interdisciplinary approach, we have built a worldwide network of experts, including veterinarians, surgeons, equine physiotherapists, and industrial partners over the past 20 years. This study aims to compare the sensitivity and repeatability of two different lameness detection approaches. Our longitudinal study will evaluate these measurements in individual horses and limbs at intervals of two to three days. The cyclic effects of hoof growth and trimming will allow us to determine and compare the sensitivity and repeatability of these two measurement approaches, and will also define the expected background fluctuations for lameness detection. This longitudinal study will include a large group of professionally managed horses in Brussels and will use a retrospective approach to test whether lameness issues could have been detected based on the data we obtain in the study.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project will investigate the evolution of limb osteology of perissodactyls (horses, rhinos and tapirs) using geometric morphometrics to gain insights into the comparative limb osteology of this group. Phylogenetic comparative methods will then be applied to the osteological data to investigate the evolution of adaptations to locomotion within the Perissodactyla, with a focus on equids (horses).

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Nauwelaerts Sandra
• Fellow: Maclaren Jamie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The fossil horse sequence is a popular example of a phylogenetic pattern resulting from the evolutionary process. However, the seemingly transitional stages are actually derived from a scattered sampling of horse fossils within the multi-branched horse evolutionary tree. The current hypothesis is that the reduction in the number of digits was necessary for the cursorial lifestyle of today's horses. Lengthening of the distal segments and toe-tip running increased the stride length and thus the speed with which the animal can move. However, to avoid the increase in cost of swinging the heavier limbs, the digital number was reduced. Reinforcement of the middle toe might have also led to an improvement of the stability. The drawback to the reduction lies in loss in versatility and a decreased ability to run on compliant substrates. This project proposes to perform detailed comparative research on horses and their extant relatives. By studying donkeys, zebras, horses and closely related species, we will detect evolutionary patterns within this group. By studying how the animals move combined with a detailed study of the limb anatomy of the same species, we aim at providing insights in the mechanisms behind the reduction in digital number. The limb movements of the animals will be studied using traditional gait analyses techniques. Video material will be obtained synchronized with ground reaction forces and pressure data under the hooves. This information can be combined with inertial information in a calculation technique called inverse dynamics that will yield the joint power profiles over time. These profiles can be regarded as indications for motor control patterns. This will allow us to compare motor control patterns between the different species. These gait analysis experiments will be done in collaboration with European zoos. Finally, a forward dynamic modeling approach (imposing patterns of joint moments of extant species onto fossil limb morphologies) will be applied. Models of trait evolution will be used to discern how limb skeletal morphology and motor control patterns have evolved in perissodactyls. This will require integration with the results of the projects running in parallel carried by Jamie MacLaren and Sandra Nauwelaerts, both now funded by the FWO-Fl (project IDs resp. 29820 & 27210).

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Nauwelaerts Sandra
• Fellow: Kaashoek Mariëlle

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project will investigate the evolution of limb osteology of perissodactyls (horses, rhinos and tapirs) using geometric morphometrics to gain insights into the comparative limb osteology of this group. Phylogenetic comparative methods will then be applied to the osteological data to investigate the evolution of adaptations to locomotion within the Perissodactyla, with a focus on equids (horses).

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Nauwelaerts Sandra
• Fellow: Maclaren Jamie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the Hercules Foundation. UA provides the Hercules Foundation research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Co-promoter: Van Ginneken Chris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

When life evolved from aquatic to terrestrial animals, a biomechanical system developed which bridges the difference in acoustic impedance between air and fluid: the middle ear (ME). If this structure would not be present, the major part of sound energy in air would reflect at the interface with the fluid-filled inner ear. In mammals, this mechanical system consists of the eardrum and three ossicles, (and two muscles and some ligaments) which act as a lever system to transform sound waves in air to sound waves with higher pressure but smaller amplitude in the fluid of the inner ear (where sound energy is transformed to electric impulses going to the brain). In birds the ME is far simpler, mainly consisting of just an eardrum and one muscle and ossicle (yet partly cartilaginous), the so called columella, directly connecting the eardrum to the oval window in the inner ear. The system is enclosed in a cavity which connects to the outside world with the Eustachian tube. Under normal circumstances this tube is closed so quasi-static pressure differences exist between the ME and the outside world, e.g. due to altitude changes, meteorology circumstances etc. Acoustic information is of primary importance to birds, so it is fascinating to see that such a relatively simple middle ear developed. Moreover, birds are typically subject to sudden height changes and the single ossicle ear does not have the same flexibility to cope with large eardrum deformations as has the mammal three ossicle ear. These fundamental questions have held the attention of many researchers in the past, but up till now no in depth model based quantitative analysis is available. In this project we will measure the necessary input parameters for such a model (elasticity of eardrum and bones, vibration pattern of the eardrum and the ossicle, high resolution anatomical shape model) and use these to develop a highly realistic finite element model of the bird middle ear. We will develop new techniques to investigate how sound energy is transported from the eardrum to the inner ear, based on transfer path and power flow analysis. This will be done for two commercially available species (e.g. pigeon or duck, and chicken), representative for birds who adapted to a life upon the ground or a life facing fast pressure changes. We will measure how pressure change influences the system, and we will investigate how pressure varies in the bird ear, another question which remained unanswered up till now. Then we will use our model to reveal the functional evolution using less common species (e.g. falcons). Finally we will use the model to investigate new designs of an artificial ME ossicle which moves like in birds, and test it in our models of the mammal ear. When in humans the ossicles are blocked or missing, a prosthesis is used to connect the eardrum to the inner ear, but such prosthesis has no flexibility to deal with static pressure changes. We want to learn from nature to see which other single ossicle designs can solve this fundamental problem.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In this study, we want to get insight in the importance, challenges and ways of balance control during voluntary dynamic locomotion in quadrupedal vertebrates. Our general hypothesis is that balance is truly a major issue for the neuro-motoric system during locomotion, achieved through control of the angular momentum. Therefore, difference in locomotor behaviour and ecology must be reflected in the functional morphology and morphometrics of the sensor involved: the vestibular system.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Van Damme Raoul

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The fossil horse sequence is a popular example of a phylogenetic pattern resulting from the evolutionary process. However, the seemingly transitional stages are actually derived from a scattered sampling of horse fossils within the multi-branched horse evolutionary tree. The current hypothesis is that the reduction in the number of digits was necessary for the cursorial lifestyle of today's horses. Lengthening of the distal segments and toe-tip running increased the stride length and thus the speed with which the animal can move. However, to avoid the increase in cost of swinging the heavier limbs, the digital number was reduced. Reinforcement of the middle toe might have also led to an improvement of the stability. The drawback to the reduction lies in loss in versatility and a decreased ability to run on compliant substrates. This project proposes to perform detailed comparative research on horses and their extant relatives. By studying donkeys, zebras, horses and the closely related rhinoceros and tapir, we will detect evolutionary patterns within this group. By studying how the animals move combined with a detailed study of the limb anatomy of the same species, we aim at providing insights in the mechanisms behind the reduction in digital number. The limb movements of the animals will be studied using traditional gait analyses techniques. Video material will be obtained synchronized with ground reaction forces and pressure data under the hooves. This information can be combined with inertial information in a calculation technique called inverse dynamics that will yield the net joint moments and power profiles over time. These profiles can be regarded as indications for motor control patterns. This will allow us to compare motor control patterns between the different species. These gait analysis experiments will be done in collaboration with European zoos. Detailed anatomical descriptions of the joint surfaces and segment proportions will be used to obtain measures for range of motion and joint center locations. These will be compared between species and will create a basis for assessing range of motion in extinct species. These descriptions will be based on 3D scans of osteological samples obtained from museum material. Models of trait evolution will be used to discern how limb skeletal morphology and motor control patterns have evolved in perissodactyls. This work will then form the basis for future work on extinct species of the Perissodactyli.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Nauwelaerts Sandra
• Fellow: Maclaren Jamie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the KMDA. UA provides the KMDA research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project proposes to perform detailed research on the domestic horse to obtain a simplified protocol that can be used to study the way horses and their relatives move. By studying donkeys, zebras, horses and the closely related rhinoceros and tapir, we will detect evolutionary patterns within this group that we hope to extrapolate to extinct species. By using virtual models of the anatomy of the extinct species, based on museum material, we aim at bringing these species to life and to deduce how they moved about in their environment. By doing so, we will be able to test whether the current members of Equus were better equipped to survive by being able to run faster or more efficiently.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Nauwelaerts Sandra

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project investigates the ability of sperm function to respond to changes in the thermal environment. Changing temperatures affect organisms during all life stages, yet reproductive phases are considered particularly sensitive 1,2. Narrow temperature windows for reproduction have profound impacts on fitness when climates change 1,3,4. Evolutionary adaptation and adaptive plasticity (e.g. thermal acclimation) can however help species cope with temperature changes 5-7. Yet, for reproduction, and gamete function in particular, these processes remain poorly understood. This is unfortunate, since studies of weak links in the chain of biological processes are crucial to estimate the ecological risks of climate change

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Aerts Peter
• Fellow: Adriaenssens Bart

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project tries to unravel some of the involved trade-offs, and will analyse the structural, functional and physiological trade-offs that exist in the buccal system of two closely related haplochromine species of Lake Victoria, both maternal mouthbrooders but representing two distinct trophic niches: a biter morph and a suction feeding morph. Trade-offs related to both sexual and trophic dimorphism will be studied in relation to mouthbrooding, with performance analyses to estimate the impact on survival and fitness.

Researcher(s)

• Promoter: De Boeck Gudrun
• Co-promoter: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

In many animals, sexual selection has produced a conspicuous diversity of morphological structures (like horns, spines, tusks, etc.) used by males in disputes over access to females. Causal insights in relationships between shape, structure and functioning of this armature, as well as in trade-offs with other functions are essential to unravel the evolutionary developmental and ecological aspects of armature. Surprisingly enough, present knowledge is largely void of this basic information. This project precisely aims at filling in this gap in knowledge via the detailed functional morphological and biomechanical analysis of armature in stag beetles. (Lucanidae)

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project aims to investigate the physiological and functional anatomical characteristics of the lower leg musculo-skeletal system that promote excellence in either sprinting or endurance running. In a first study we aim to develop a non-invasive and innovative technique to measure muscle fiber type composition (percentage slow vs. fast fibers), a well known antagonistic pair of traits for performance.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project tries to unravel some of the involved trade-offs, and will analyse the structural, functional and physiological trade-offs that exist in the buccal system of two closely related haplochromine species of Lake Victoria, both maternal mouthbrooders but representing two distinct trophic niches: a biter morph and a suction feeding morph. Trade-offs related to both sexual and trophic dimorphism will be studied in relation to mouthbrooding, with performance analyses to estimate the impact on survival and fitness.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: De Boeck Gudrun
• Co-promoter: Van Wassenbergh Sam

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Sexual selection favors the evolution of traits that affect the reproductive success of individuals, traits that are important in male combat and male signals used by females during mate choice. As even small differences in these traits can result in a large variance in reproductive success, their evolution can be rapid and apparently unlimited. Differentiation of these traits may occur in populations with varying social conditions (e.g. density, sex-ratio) and the hypothesis of speciation by sexual selection states that when a parallel change in female mate preference and male sexual traits occurs within a population, this population might become reproductively isolated from others. With this project I will test this hypothesis, and investigate the role of sexual selection mechanisms in population divergence, and ultimately speciation. Therefore, I will use a dual approach. First, I will conduct a comparative study of natural populations of the Dalmatian wall lizard Podarcis melisellensis to describe the variation in sexual traits among populations of varying density and compare it with neutral variation and variation in naturally selected traits. Second, I will test to what extent sexual traits diverge when the social environment of a population is manipulated. This will be done by experimentally manipulating the density and sex-ratio of killifish populations (Austrolebias sp.) under laboratory conditions.

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Aerts Peter
• Fellow: Huyghe Katleen

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In the literature it has been shown that gibbons are able to brachiate with very low mechanical costs on a horizontal, rigid substrate. They do this by pendular movements, where potential and kinetic energy are exchanged to create an optimum energy conservation. Moreover they must minimize their collisional energy losses by ensuring that the passage between two movements happens smoothly without abrupt change in the path of body center of mass. Although the animals appear to succeed to do this in uniform, predictable experimental circumstances, this can not offer a thorough insight in the degree of coordination and control which these animals might show in their habitual, more complex, surroundings. In this research it will be assessed, by means of a gradually increased degree of complexity, what the impact is of compliance of branches and their heterogeneous spacing on the mechanical costs of brachiation and whether and how kinesiological adaptations are realised. Moreover it will be examined whether siamangs show a motor learning process or not. If a learning process would exist, we expect reduction of the mechanical costs after familiarisation to a specific set-up. To examine all this thoroughly, anatomical, kinematic and dynamic analysis are carried out.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Michilsens Fana

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Darwin's finches (Geospizinae) have become a model system for the study of adaptive radiaton. From a single ancestor, thirteen species of Darwin's finches have radiated on the Galápagos Islands, have specialized on different food resources and differ in beak form. Despite the importance of beak size and shape in Darwin's finches ecology, the mechanical link between these aspects of beak morphology and the ability of a bird to crack seeds of different size and hardness remains unknown. Those biological theories can only be validated or refuted by an interdisciplinary approach, based on physical computational modelling. International cooperation supplies us of rare specimens from different species. The in-vivo biting force and place, CT images and histological cuts from different (protected) Darwin's finches and the physiological cuts from which the maximum muscle force could be calculated are important to make a realistic model. The research consists of two parts. First we have the computer modelling part (Finite elements simulations with FEBio), and second, an experimental part for judging the necessary boundary conditions for the simulation, hence validating and optimizing the FE model. Converning the validation, we will use the more common java finches (Padda oryzivora).

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Fellow: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the Flemish Public Service. UA provides the Flemish Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Van de Heyning Paul
• Co-promoter: Aerts Peter
• Co-promoter: Pieters Luc
• Co-promoter: Truijen Steven
• Co-promoter: Wuyts Floris

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

Strikingly little is know about the evolution of a terrestrial feeding apparatus in the first terrestrial tetrapods. The purpose of the proposed research is to gain functional morphological insight in the way that the cranial and postcranial musculoskeletal system works during terrestrial feeding in extant amphibious fishes. This insight will form the basis to identify potential preadaptation to terrestrial feeding in the fossil record.

Researcher(s)

• Promoter: Van Wassenbergh Sam
• Co-promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Not all children learn to crawl on hands and knees. Some of them show other patterns of locomotion, like bottom shuffling, creeping or rolling. It is assumed that these children show a weaker coordination between legs and arms and shoulder- and pelvisgirdle. The aim of this study is (1) examine whether there is a correlation between developmental factors and different crawling patterns and (2) to develop a method to measure the crawling coordination in an objective way.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This is a fundamental research project financed by the Research Foundation - Flanders (FWO). The project was subsidized after selection by the FWO-expert panel.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Van Wassenbergh Sam

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The overall objective of the proposed research is to define biomechanical control of forelimb movement through musculoskeletal modeling combined with empirical gait tests. Our hypotheses are: (1) the tendons, working passively to control the distal joints of the forelimbs, are stretched more when limb loads are increased; (2) overstretching can be prevented in actively controlled joints via increased muscle force; (3) joint reaction forces (and torques) increase in reaction to load increase; and (4) joint reaction forces (and torques) change direction as loads increase.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Nauwelaerts Sandra

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Locomorph's goal is to push beyond the state of the art in robotic locomotion and movements, by increasing efficiency, robustness, and thus usability in unknown environments. As robotic research and industry are competing to increase robots' usability towards the highly-in-demand service robotics, advancements in robotic locomotion today would give Europe a significant competetive advantage. Locomorph combines multidisciplinary approaches from biology, biomechanics, neuroscience, robotics, and embodied intelligence to investigate locomotion and movements in animals and robots, focusing on two concepts: morphology and morphosis.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This projects investigates the transitions between different gait types (walk-run/trot; trot-gallop; walk-gallop and vice versa) during actual overground accelerations/decelerations. Kinematics, ground reaction forces, and EMG patterns are collected and data are used for further calculations (mechanical energy, inverse dynamic modeling¿). Ultimately, the project aims at gaining insights in the interaction between mechanical and neural control of transitions (locomotion in general).

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

When fish want to catch their prey underwater, their feeding apparatus must meet specific demands due to the relative high viscosity and density of water. To handle the physical properties of water, most fish will use suction feeding. However, a remarkable diverisity of cranial morphology can be found among fishes. A striking example exists in the family of Syngnathidae (seahorses and pipefishes). Their cranial morphology is characterized by a long, tubular snout with relatively small jaws at its end. Such a morphology predicts several limitations: firstly, the prey size is constrainted due to the small opening of the mouth. Secondly, when sucking through a narrow tube (i.e. snout), energy loss due to friction drag can probably no longer be neglected. To deal with these limitations the cranial morphology of this family must be specialised. The main goal of this study is to make a detailed study of the working of the headmorphology in these animals and to examine in wich way this extreme cranial morphology is specialised.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Roos Gert

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Independent Walking is one of the most important goals in motor development of young children. They learn this skill when their body is in full growth. Previous research in the laboratory for Functional Morphology of the University of Antwerp showed how toddlers, between one and two years old, handle the challenge of learning to walk. However little is know about the relationship between motor development and the growth status of infants. This research project studies the influence of individual morphological differences and ontogenetic changes of the morfotype on control and maturation of gait during childhood.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Van Dam Marleen

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In the literature it has been shown that gibbons are able to brachiate with very low mechanical costs on a horizontal, rigid substrate. They do this by pendular movements, where potential and kinetic energy are exchanged to create an optimum energy conservation. Moreover they must minimize their collisional energy losses by ensuring that the passage between two movements happens smoothly without abrupt change in the path of body center of mass. Although the animals appear to succeed to do this in uniform, predictable experimental circumstances, this can not offer a thorough insight in the degree of coordination and control which these animals might show in their habitual, more complex, surroundings. In this research it will be assessed, by means of a gradually increased degree of complexity, what the impact is of compliance of branches and their heterogeneous spacing on the mechanical costs of brachiation and whether and how kinesiological adaptations are realised. Moreover it will be examined whether siamangs show a motor learning process or not. If a learning process would exist, we expect reduction of the mechanical costs after familiarisation to a specific set-up. To examine all this thoroughly, anatomical, kinematic and dynamic analysis are carried out.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: D'Aout Kristiaan
• Co-promoter: Vereecke Evie
• Fellow: Michilsens Fana

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Darwin's finches (Geospizinae) have become a model system for the study of adaptive radiaton. From a single ancestor, thirteen species of Darwin's finches have radiated on the Galápagos Islands, have specialized on different food resources and differ in beak form. Despite the importance of beak size and shape in Darwin's finches ecology, the mechanical link between these aspects of beak morphology and the ability of a bird to crack seeds of different size and hardness remains unknown. Those biological theories can only be validated or refuted by an interdisciplinary approach, based on physical computational modelling. International cooperation supplies us of rare specimens from different species. The in-vivo biting force and place, CT images and histological cuts from different (protected) Darwin's finches and the physiological cuts from which the maximum muscle force could be calculated are important to make a realistic model. The research consists of two parts. First we have the computer modelling part (Finite elements simulations with FEBio), and second, an experimental part for judging the necessary boundary conditions for the simulation, hence validating and optimizing the FE model. Converning the validation, we will use the more common java finches (Padda oryzivora).

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Fellow: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The specific goals of this project are to investigate the presence of a central pattern generator (CPG) controlling feeding behaviour in Squamates and to test hypotheses of constraint on the evolution of motor control. The data will be used to create a model for the control of food transport in an 'ancestral lizard' which will be compared to data available for mammals and other vertebrates.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Schaerlaeken Vicky

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Biomechanics of locomotion in complex environments: brachiation in siamangs (Symphalangus syndactylus) In the literature it has been shown that gibbons are able to brachiate with very low mechanical costs on a horizontal, rigid substrate. They do this by pendular movements, where potential and kinetic energy are exchanged to create an optimum energy conservation. Moreover they must minimize their collisional energy losses by ensuring that the passage between two movements happens smoothly without abrupt change in the path of body center of mass. Although the animals appear to succeed to do this in uniform, predictable experimental circumstances, this can not offer a thorough insight in the degree of coordination and control which these animals might show in their habitual, more complex, surroundings. In this research it will be assessed, by means of a gradually increased degree of complexity, what the impact is of compliance of branches and their heterogeneous spacing on the mechanical costs of brachiation and whether and how kinesiological adaptations are realised. Moreover it will be examined whether siamangs show a motor learning process or not. If a learning process would exist, we expect reduction of the mechanical costs after familiarisation to a specific set-up. To examine all this thoroughly, anatomical, kinematic and dynamic analysis are carried out.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Vereecke Evie
• Fellow: Michilsens Fana

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The overall goal of this project is to investigate to what degree the extreme morphological specialisation of the feeding system in syngnathids has constrained its functional capacity, and to explore whether this can explain the reduced ecological resilience of syngnathids in the face of changing ecological settings (i.e. changes in trophic resources).

Researcher(s)

• Promoter: Herrel Anthony
• Co-promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

When fish want to catch their prey underwater, their feeding apparatus must meet specific demands due to the relative high viscosity and density of water. To handle the physical properties of water, most fish will use suction feeding. However, a remarkable diverisity of cranial morphology can be found among fishes. A striking example exists in the family of Syngnathidae (seahorses and pipefishes). Their cranial morphology is characterized by a long, tubular snout with relatively small jaws at its end. Such a morphology predicts several limitations: firstly, the prey size is constrainted due to the small opening of the mouth. Secondly, when sucking through a narrow tube (i.e. snout), energy loss due to friction drag can probably no longer be neglected. To deal with these limitations the cranial morphology of this family must be specialised. The main goal of this study is to make a detailed study of the working of the headmorphology in these animals and to examine in wich way this extreme cranial morphology is specialised.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Roos Gert

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Research of energetics during gait already started in 1950. There still is no clearness on the correlation between mechanical and metabolic energy use. Fine tuning of the insights in energy use during walking can be very useful for clinical interpretation of loss of efficiency in pathological gait. In this project we want to create a base for clinical interpretation by investigating the correlation in children with a normal gait pattern.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Afferent information is crucial in the control of voluntary movements. This information comes from the visual, vestibular and somatosensory systems. Visual information is crucial for maintaining balance in a static situation. However, during the execution of a movement, a situation of dynamic equilibrium needs to be maintained. It is logical to assume that vision also is important in these situations. Furthermore, vision may also play a role in the coordination of movements. This research project studies the effects of visual deprivation on the control and development of walking using biomechanical gait analysis.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Measurements of shape and material parameters are measured and incorporated in a finite element model for investigation of the functional characteristics of muscular-sceletal cranial structures of Darwin finches, to gain understanding of phenotypic variation and ecological diversity.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Fishes are undoubtedly one of the most diverse groups within the vertebrates. The cranial morphology of a vast number of species diverges considerably from the generalised fish "Bauplan". Striking examples of this are the seahorses and pipefishes (Family Syngnathidae), a group of extremely specialized suction feeders with a narrow gape at the end of a tubular snout. For fishes with such extreme morphologies, none of the assumptions of the existing biophysical models are justified. Therefore, the need for new analytical techniques arises. Consequently, this group is particularly suitable to study the function and constraints of extremely specialised suction feeding systems.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Van Wassenbergh Sam

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Independent Walking is one of the most important goals in motor development of young children. They learn this skill when their body is in full growth. Previous research in the laboratory for Functional Morphology of the University of Antwerp showed how toddlers, between one and two years old, handle the challenge of learning to walk. However little is know about the relationship between motor development and the growth status of infants. This research project studies the influence of individual morphological differences and ontogenetic changes of the morfotype on control and maturation of gait during childhood.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Van Dam Marleen

Research team(s)

• Functional Morphology

Project website

Project type(s)

• Research Project

Abstract

This project entails a detailed biomechanical analysis of hylobatid jumping, with a particular emphasis on the role of internal (muscle, tendons, ligaments) and external (substrate) elastic structures. In a first part of this study, we will determine the elastic properties of the tendons in the hindlimbs of gibbons, using experimental tests on cadaver specimens. The second part of the project will analyse the kinematics and kinetics of the push-off phase during jumping from a stiff and a compliant substrate. This should allow us to evaluate the role of the internal elastic structures during jumping, and how these interact with the changing substrate properties. The aim is to get insight in the interaction between internal and external elastic structures during hylobatid jumping and to investigate if kinematics and instantaneous muscle-tendon properties can be accurately tuned to changes in substrate properties so that internal and external elastic structures can be applied optimally to enhance the jumping performance.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vereecke Evie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Jumping in frogs is a peculiar mode of locomotion, which together with the derived anatomy of the pelvic girdle, makes it unique among vertebrates. Frog hindlimbs are much more developed than the anterior ones, the tail is vestigial and the ilia are elongated posteriorly so that the pelvic joint is located behind the sacrum. There are two major hypotheses attempting to explain origin of the saltatory locomotion in frogs and the unique derived anatomy of the locomotor apparatus. The first is largely based on the fossil record, and argues that frogs evolved from larval (i.e., water dwelling) temnospondyl amphibians (i.e. that frogs are derived from aquatic ancestors). The second hypothesis emphasizes a strictly terrestrial origin of frogs, and uses as the predominant argument against the first hypothesis that there would be no reason to modify undulatory swimming movements and to reduce the tail of the ancestral temnospondyl larvae if the transition from the pre-anuran to anuran stages would occur exclusively in water. We are convinced that this controversy cannot be solved unless we understand the functioning of the anuran pelvic girdle and its musculature during locomotion. We therefore propose to investigate terrestrial and aquatic locomotion and the anatomy of the pelvic girdle in frogs that have specialized into different locomotor modes (i.e. swimmers, jumpers, diggers and crawlers). Additionally we want to study the functioning of the locomotor system during the ontogenetic transition from water to land. This kind of data should allow for a better interpretation of the fossil evidence and allow us to determine the evolutionary origin of this unique locomotor mode.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Co-promoter: Van Damme Raoul

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The specific goals of this project are to investigate the presence of a central pattern generator (CPG) controlling feeding behaviour in Squamates and to test hypotheses of constraint on the evolution of motor control. The data will be used to create a model for the control of food transport in an 'ancestral lizard' which will be compared to data available for mammals and other vertebrates.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Schaerlaeken Vicky

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Linking kinematics of the foot-ankle complex, plantar pressures and static footprints: a new approach for the functional interpretation of fossilised hominid tracks. Footprints, left behind in a deformable substrate, contain information about the anatomy and locomotor mechanism of the maker. The latter can be a hominin ancestor, in the case of fossilised prints, but also a modern human (e.g. in forensic research). The current project aims to unravel the complex interaction between the factors influencing the footprint's morphology. Both experimental and modelling approaches are used in three consecutive steps: (1) analysis of the relationship footprint-plantar pressure, (2) analysis of the relationship plantar pressure-kinematics and (3) combination of these results, verification and interpretation of known fossil footprints (e.g. the Laetoli prints, Tanzania).

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The proposed research project aims at giving insight into the development of walking in toddlers trough comparison of the normal immature gait pattern to the gait pattern of children showing a delay in motor development. Insight in motor control is gained by the study of foot function, kinematics and kinetics. The required techniques are extremely labour-intensive and for correct analysis and interpretation of the results sufficient knowledge is required.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The evolution of a terrestrial feeding mode and the origin of the amniote skull structure have undoubtably been key phenomena in the evolution of vertebrates. Althoug there is a substantial body of work, dealing with the craniocervical structure and feeding systems in mammals and birds, relatively little is known about these systems in lower tetrapods. Still, the study of these basal groups is essential to gain insights in the evolutionary processes that shaped the feeding system. Within the scope of this post-doc two topics are proposed for further study. First, the neuromotor basis of feeding in lizards will be examined. Here, emphasis will be placed on investigations into the presumed stereotypy of feeding motor patterns. Additionally we will investigate the presence, prevalence and importance of feedback systems in the evolution of lizard feeding systems. The second question I would like to address within the scope of this post-doc concerns the ecomorphological relations of the feeding apparatus in lizards. Using a broad, comparative approach within a strict phylogenetic context, we will investigate the importance of several performance parameters of the feeding system in lizards. This should allow us to identify those elements which played a critical role in the evolutionary diversification of the feeding system in lizards. The techniques and statistical methods that will be used to analyse these types of data (which will be learned in the lab. of Dr. D. Irschick, Tulane University - New Orleans), will eventually also be used to analyse the evolution of neuromotor control of the feeding system in lizards.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Herrel Anthony

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The question can be asked why bipedalism has only become obligatory in the genus Homo. Indeed, all recent genera of the Hominoidea show in more or less degree bipedalism in their locomotory repertoire. Hereby it attracts the attention that the closest relatives of man make only use in a limited degree of bipedal locomotion, despite the large morphological and morphometrical similarity. Gibbons, the furthest relatives of man, are in contrast, the most bipedal of all non-human primates and this despite their specific adaptations to an other type of locomotio, namely brachiation. The group where the extant Hylobates species belong to, has split off approximately 20 million year ago from the line leading to the Hominidae. It is thus not unlikely that the bipedal locomotion of Hylobates developped independently of this occuring in more recent genera as Pan and Homo. To sustain (or to reject) this hypothesis, we first have to answer the following question: what are the functional morphological and kinesiological differences and similarities between the bipedalism of Hylobatidae and Hominidae? This proposal is an extension of the current FWO-project (G.0209.99) where the locomotion of the bonobo is analysed in an evolutive context. This implicates that this Ph.D. study shall in first instance focus on the kinesiology and morphology of the locomotory apparatus of Hylobates. Although already many studies exit about brachiation in this genus, the kinesiology of the bipedal locomotion has not yet been studied in detail. A profound analysis of the foot structure is an essential complementation, necessary for the interpretation of this biomechanical study. In second instance there will be reverted to the results of the above-mentioned biomechanical research of the bonobo (and human) to conduct the comparison of their bipedal locomotion. Because a detailed study of the foot of Pan paniscus is not a topic of the inter-university FWO-project mentioned, the morphological analysis of the bonobo foot is also included in this Ph.D. proposal.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vereecke Evie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In many species, high-ranking males have a higher reproductive success than do subordinate males. For males, dominance and reproductive success can be closely linked. Less competitive, subordinate males are expected tot pursue alternative mating strategies. The dominance position is influenced by different individual features, such as age and weight, and by group features, such as group composition, size and agestructure. For bison bulls (Bison bison), the brief breeding season (rut) results in making a maximum effort in minimum time. Bison bulls show extreme competition and this has consequences for the relationships between bulls. The main objective is to study the intrasexual competitive relationships and mating strategies of American bison bulls in semi-natural conditions. Therefore the dominance relationships between bulls, their reproductive success and reproductive investment will be determined. The effect of individual features (age and weight) and of group features (herd composition, herd size and age combinations) on the afore-metioned factors will be studied. Moreover the link with endocrinology will be made by analysing the levels of stress and sex hormones (cortisol and testosterone) of the animals. It has been assumed, based on observations, that the most dominant males breed a very large part of the cowherd. For lack of paternity data this supposition has never been proved. Our aim is to reliably quantify the reproductive success of the bulls by means of DNA-analyses. Reproductive investment will be quantified and is expected to 1) increase with age and 2) change during the rut in function of time and status. With regard to methodology, the dominance relationships of the bulls will be determined by observation of agonistic behaviour in two different periods: 1) during the rut, when there is competition for breeding partners, and 2) during winter, when there is mainly food competition. During these observations feacal samples will be collected and analysed for testosterone and cortisol levels. Once a year the animals are weighed and bloodsamples are obtained. These samples will be used to perform paternity tests. These data will be compared to the observed copulations and will provide a reliable measure of reproductive success. Reproductive investment will be studied by measurement of the bulls time budgets (proportion agressive and sexual behaviour) and their engagement in risky agression. In spite of their increasing economic value, there is still a lack of knowledge on the reproductive strategies and sexual competion of bison bulls.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Roden Catherine

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The BAMOS project wants to gain profound insight into the motor development in young childeren through advanced biomechanical analyses. We focus on the ontogeny of walking in toddlers as acquiring this skill put strong demands upon the musculo-skeletal control (of equilibrium) and coordination.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In this project the evolution towards a highly specialised feeding apparatus, i.e. that foralgae scraping by means of a sucker mouth, will be studied. Such a high level of specialized feeding has only been observed in tadpoles and tropical catfishes. With a multidisciplinary approach, this projects objectives are to study the ontogeny, function and evolution of such an algae scraping apparatus in three families of tropical catfishes.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The major aim of this project is to investigate which morphological, physiological and behavioural characteristics determine survival and reproductive success in a lacertid lizard. I will follow the research scheme proposed by Arnold (1983), which means that I will examine the relationship between design and performance (the performance gradient) and between performance and fitness (the fitness gradient). Because of the complexity of this task, I will restrict myself to one species of the Lacertidae: the Canary Island lizard Gallotia galloti. At the design level of the males of this species, I will measure some morphological (morphometry, coloration, femoral pores,...) and physiological (immune system, hormones) characteristics. Also many kinds of performance will be measured: locomotion, bite force, fighting ability and parasite load on a primary level and territorial quality, foraging success and mating success on a secondary level. Because Gallotia galloti is an ectotherm organism, body temperature is a key factor in this scheme and will have an important influence on all kinds of performance. All these design and performance parameters will be linked with each other and with survival and reproductive success, on the basis of theories and hypotheses concerning natural selection s.s., intrasexual selection (competition between males) and intersexual selection (female mate choice). These hypotheses and supposed links will be tested by correlative analyses based on field data, supplemented with laboratory experiments. During the field study (taking up several months a year on Tenerife), males will be marked to allow permanent identification and the following data will be collected: morphometry (snout vent length, body mass, head size, limb length); area of the blue chin spot; blood samples (in order to determine testosterone levels and immunocompetence); parasite load, courting behaviour and copulations; aggressive behaviour towards other males and contests; territorial area and quality. These data will allow us to investigate the link between, for instance, territorial quality and mating success or between head size and dominance. Annual survival will be estimated with capture-recapture techniques. Laboratory experiments will include: - Tests of locomotor capacity (sprint speed, endurance and manoeuvrability) in order to investigate biomechanical relationships between body shape and function, to reveal possible trade-offs between different locomotion patterns and to estimate the effect of locomotor capacity on survival. - Staged contests between males to identify parameters affecting fighting ability. The following parameters will be tested: body size, head size (relative to body size), body temperature, testosterone level, area of the blue chin spot, residence and prior experience. - Tests of female mate choice, based on visual and/or chemical signals. - Phenotypic engineering with testosterone in order to test the immunocompetence handicap hypothesis (Folstad & Karter, 1992).

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Van Damme Raoul
• Fellow: Scheers Hans

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Within a few months, infants adopt the co-ordination required for a stable habitual walk. Two ways of analysis are open to study this development. In the phenomenological approach (dynamical systems approach), the complex system is reduced to a few variables considered to be the collective result of the dynamical behaviour of all of the systems components. Analysis of variance of the cyclic behaviour of these variables offers insight in the developmental processes (Thelen & Smith, 1994; Clark, 1997). In case of the mechanistic approach, insight is gained in the causes underlying the cyclic behaviour through detailled analysis of the structure and biomechanics of the locomotor 'de nieuwe loper', we verwachten eerder een aantal algemene trends te kunnen system. vaststellen. The phenomenological and mechanistic approaches are to be considered as highly complementary in understanding the fenomenon of motor development. Most of the longitudinal studies investigating the early development of independent walking, preferably used the phenomenological approach, hereby not taking into account a few exceptions (Sutherland et al.,1980; Grimshaw et al.,1998). Our project tends to gain insight in the biomechanical causes underlying the observerd changes in children learning to walk. As mentioned in literature, independent walking requires the combination of balance and the generation of a propulsive movement. We tend to investigate how this challenge is realised by the morphology of a toddler, wich differs from the adult morphology, by means of detailed 3D- kinematical analysis, together with measurement of the 3D-ground reaction forces, the pressure distribution pattern under the feet (registrated with high spatial and temporal resolution) and perhaps electromyographical registration. Attention is paid to the dynamics of the the center of mass and the body segments. Kinetics and energetics will teach us how much energy it costs to walk. Joint-moment are used to calculate wich joints produce energy and where the energy disappears. We will also study the forces and pressures under the feet and the pathway of the center of pressure. In combination with the ground reaction forces, this information allows us to determine the stability in the joints. Attention must also be paid to the occasional trials when the child fails to stay upright. Wich parameter differs and make the infant lose his balance? Amongst children the variability in gait patterns is large, therefore it is not our goal to define an average gait pattern of 'the new walker'. Rather we want to determine some general trends in the development of independent walking.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Because water is 800 times denser and 50 times more viscous than air, it puts very strong demands on the feeding system of vertebrates. An aquatic predator that approaches a prey will generate bow waves that can either push the prey further away or along a predator's jaws. To avoid or compensate for those bow waves, we find two systems among aquatic vertebrates: filter feeding and suction feeding. However, aquatic snakes seem not able to perform filter- or suction feeding because of their very specialised head morphology (for the consumption of large prey). Still more than 300 snake species feed in an aquatic environment on a variety of prey and with a range of different feeding morphologies and behaviours. High-speed video recordings and Particle Image Velocimetry on the strikes of Natrix maura and N. tesselata with altered predator and prey characteristics will allow us to gain insight in how the process of aquatic feeding in snakes precisely works and through which factors this process is influenced. This information will be completed with measurements on a physic snake model to look at the effects of a broader range of prey- and predator characteristics (functional morphology part). Finally we will try to consider if it is possible with the obtained insights, to link the large variation in head morphology and feeding behaviour among aquatic snakes, to the variety of different prey they eat (ecomorphological part). Data on the head morphology of aquatic snake species will be obtained by measuring museum species; data on the feeding behaviour and diet of aquatic snake species will be collected from literature.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Fellow: Bilcke Joke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

This project aims to perform such a test. Gambusia holbrooki, a small poeciliid fish, will be used as a model. The species has recently been introduced in a wide variety of thermal habitats and clearly shows the capacity to acclimate. Locomotor capacity will be used as the model function. It is generally believed that swimming speed and endurance are ecologically relevant, because they would contribute to both survival and reproductive success.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Van Damme Raoul
• Fellow: Adriaenssens Bart

Research team(s)

Project type(s)

• Research Project

Abstract

The evolution of habitual bipedalism is a key event in the evolution of early hominids. Two major theories about `the how and why' of the involved evolutionary changes exist. Both are based on a limited set of paleontological data only. The first theory, the terrestrial theory, suggests that habitual bipedalism evolved from terrestrial quadrupedal locomotion. The resemblance between the scaphöids of apes and early hominids, for instance, has recently been used to argue that bipedalism arose from quadrupedal knuckle walking. The second theory, the arboreal theory, suggests that arborealism is preadaptive to habitual bipedalism. This theory also builds on indirect morphological facts and no convincing evidence is found thus far. On the other hand, it can be argued that both arboreal climbing and terrestrial bipedalism require propulsive forces to be mainly delivered by the hind limbs, or that climbing, like bipedal walking, involves an independent use of fore and hind limbs. Again, however, the conclusive force of such functional considerations remains limited. In order to evaluate evolutionary theories on locomotion more decisively, profound biomechanical analysis is required. Since experimental studies on extinct species are impossible, comparative kinesiological research on extant model species, preferable primates, can offer a way out. In that case it is essential that all locomotion types central to the theories to be tested, belong to the natural repertoire of the model species. To date, only few biomechanical studies on primates address arboreal locomotion. Therefore, this project wants to evaluate the arboreal theory through kinesiological analysis of the climbing locomotion in the bonobo (Pan paniscus). A comparison between the manner in which the musculo-skeletal system functions in quadrupedal and bipedal climbing, as well between climbing and terrestrial locomotion will be made. This species fulfils the essential condition mentioned above: in nature, arboreal as well as terrestrial quadrupedalism and bipedalism are observed. In addition, morphometric and paleo-ecological arguments support this choice of model species. In practice, an integrated experimental set-up will be built, from which 3D-kinematic data (whole body or details of hands and feet) of arboreal locomotion can be obtained simultaneously with substrate reaction forces (either for the whole body or feet and hands separately). When combined with morphometric information (linear dimensions as well as inertial properties) these data will allow us to estimate through inverse dynamic modelling, the manner in which the musculo-skeletal system functions. Mechanical locomotor costs can be calculated. A variety of conditions (different slopes and diameters of substrate) will be compared. The results obtained for quadrupedal and bipedal arboreal performance will be integrated with the data obtained from a parallel study dealing with terrestrial locomotion. This must allow for a reliable evaluation of the arboreal theory.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Schoonaert Kirsten

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Next to plants, insects make up a smaller, but regular part of the diet of sympatric western lowland gorillas (G. g. gorilla) and chimpanzees (P. t. troglodytes). This study, in recently exploited rainforest in south-east Cameroon, is the first one that investigates simultaneously the consumption of insects by both ape species, and the abundance and temporal activity of the preys (especially ants and termites) in the study area. The aim is to find whether both great apes show different strategies (niche differentiation) in their insectivorous behaviour. We expect that the temporal variations in the frequency of insect-eating by gorillas and chimpanzees are not mutually correlated, and are explained by other factors in both species. In order to test this hypothesis the following parameters must be considered: 1) the composition of the insect and plant (fruit and foliage) diet of chimpanzees and gorillas during a period of one year, and 2) the spatio-temporal distribution of these resources. First, the insect composition of the diet will be compared between both apes. Secondly, the relation will be investigated between the temporal variation in the frequency of insectivory and 1) the spatio-temporal availability of insects in the forest, and 2) the seasonal variation of plant food in the diet. The composition and the monthly distribution of the insect and plant proportion in their diet will be determined by analysing faecal samples and feeding traces. All feeding remains will be identified and quantified. Data collection on the distribution of plant food in the different vegetation types and identification of the plant feeding remains will be done by botanists present in the project. I will estimate the relative densities of the ant and termite prey in these vegetation types by using a belt-transect method and I will follow up the temporal activity of the preys by regular visits to their nests and by using a pitfall-method. If the results confirm the hypothesis noted earlier, differences in feeding on insects by gorillas and chimpanzees can be interpreted in terms of niche differentiation.

Researcher(s)

• Promoter: Aerts Peter
• Promoter: Verheyen Rudi

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The apparently perfect fit between the form of an organism and its environment had intrigued biologists for meny centuries. While 19th century naturalists explained this near perfect form-function match as the work of a `Divine Designer', Charles Darwin (1859) used the same observation as an argument for the power of evolution by natural selection. An unconditional faith in the power of natural selection as an optimizing agent, lead `traditional' evolutionary biologists to follozing the adaptationist programme. In 1983, however, Stevan Arnold proposed a method to explicitly test the presence of adaptations. He suggested breaking up the adaptation process into two components: a performance and a fitness gradient. Whereas the performance gradient is defined as the effect of variation in design on variation in performance, the fitness gradient is defined as the effect of variation in performance on variation in fitness. In most organisms, fitness is influenced not just by one, but rather by multiple performance traits simultaneously. If these performance traits pose conflicting demands on the same design traits, evolutionary trade-offs occur which may obscure ecomorphological relationships. To be able to understand the relationships between design, performance and fitness it is therefore necessary to quantify and intercorrelate various performance traits. Design conflicts can originate because natural selection s.s. and sexual selection may act in opposing ways. Sexual dimorphism is an obvious results from such a conflict. In this context, the link with fitness has seldom been tested. Hypotheses and models regarding sexual selection have been tested extensively using design traits. In most such cases, sexual traits are directly correlated to the survival and reproductive success of the individual. In this project, I study the mechanism by which these correlations come about, and why sexual traits may have negative effects. As modelorganisms I use lizards belonging to the family Lacertidae and the genus Anolis.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vanhooydonck Bieke

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The question can be asked why bipedalism has only become obligatory in the genus Homo. Indeed, all recent genera of the Hominoidea show in more or less degree bipedalism in their locomotory repertoire. Hereby it attracts the attention that the closest relatives of man make only use in a limited degree of bipedal locomotion, despite the large morphological and morphometrical similarity. Gibbons, the furthest relatives of man, are in contrast, the most bipedal of all non-human primates and this despite their specific adaptations to an other type of locomotio, namely brachiation. The group where the extant Hylobates species belong to, has split off approximately 20 million year ago from the line leading to the Hominidae. It is thus not unlikely that the bipedal locomotion of Hylobates developped independently of this occuring in more recent genera as Pan and Homo. To sustain (or to reject) this hypothesis, we first have to answer the following question: what are the functional morphological and kinesiological differences and similarities between the bipedalism of Hylobatidae and Hominidae? This proposal is an extension of the current FWO-project (G.0209.99) where the locomotion of the bonobo is analysed in an evolutive context. This implicates that this Ph.D. study shall in first instance focus on the kinesiology and morphology of the locomotory apparatus of Hylobates. Although already many studies exit about brachiation in this genus, the kinesiology of the bipedal locomotion has not yet been studied in detail. A profound analysis of the foot structure is an essential complementation, necessary for the interpretation of this biomechanical study. In second instance there will be reverted to the results of the above-mentioned biomechanical research of the bonobo (and human) to conduct the comparison of their bipedal locomotion. Because a detailed study of the foot of Pan paniscus is not a topic of the inter-university FWO-project mentioned, the morphological analysis of the bonobo foot is also included in this Ph.D. proposal.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vereecke Evie

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Many authors (beginning with Pianka 1966) suggest that an animal has to choose between two highly different foraging strategies: sit and wait foraging (SW), where the animal stands still and waits for a suitable prey to pass by, and active foraging (AF), where the predator actively looks for the suited food. It is often supposed (among others by McLaughlin 1989) that each foraging strategy goes with a series of morphological, behavioural and ecological characteristics (like acceleration capacity, stamina, muscle composition, daily energy demands, diet, prey detection, anti-predator behaviour, habitat choice and thermoregulation). This is called the 'syndrome hypothesis'. Such dichotomy in foraging strategy and the correlated characteristics has been very popular in herpetology for a long while, although there is only little empirical evidence. Even a consensus about the quantitative characterization of an animal as SW or AF doesn't exist. It is suggested recently (see for example Perry 1999) that the dichotomy is false and that there is in fact a continuity in foraging strategies. Further were the fylogenetic relations often not taken in account in the many studies that confirmate the syndrome hypothesis. Therefore, the value of the eventually found differences can not properly determined. This study will evaluate how, within the family Lacertidae, the foraging mode is correlated with characteristics on different levels (stamina, acceleration capacity, ratio red muscle fibers/white muscle fibers in the locomotion apparatus, diet, habitat choice, chemoreceptory capacity), among others with the intention of evaluating the syndrome hypothesis. The phylogeny of the family is relatively well established, so that the interspecific comparisons can take place in an explicitely phylogenetic context. Finally, the found results could give insight in the oevolution of the studied characteristics.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Verwaijen Dave

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Motion analysis is one of the important tools in the functional morphological study of the evolution of musculo-skeletal systems as it, in combination with other functional data (such as muscle activation patterns, force measurements, etc...), allows the determination of the functional demands on the system in its ecolocical context. Whenever movement patterns can be determined externally, the analyses thereof involve the digitisation of conventional video sources (at low or high speeds, depending on the application under study ). However, often essential movements of the musculo-skeletal system of interest cannot be observed externally as the structures are covered by skin, fur or feathers (eg. movements of the pectoral and pelvic girdles in running animals, movements of the tongue and hyoid apparatus during feeding, air flow through the lungs during breathing,...). In all such cases cineradiography is "the tool of choice" to visualise these movements. In cineradiographic analysis the object under study is "illuminated" by a X-ray generator emitting pulsed or continuous X-rays. The emitted radiation is partially absorbed (depending on the density and absorption capacity of the tissue), and is received by an image intensifier and turned into a visual image. In the past, this image was generated by a phosphorising screen that, in turn, was filmed by means of a regular film camera. By synchronising the pulse frequency emitted by the generator and the shutter of the camera, movements could be recorded accurately. However, the recording speed was inherently limited by the fairly long decay time of the phosphorising screen. As for most technical applications, the recent advances in digital technology have had an enormous influence on cineradiographic techniques which has resulted in direct, digital video imaging of the cineradiographic images. This has a number of important advantages over the older technique.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: De Vree Frits
• Co-promoter: Herrel Anthony
• Co-promoter: Van Damme Raoul

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The major aim of this project is to investigate which morphological, physiological and behavioural characteristics determine survival and reproductive success in a lacertid lizard. I will follow the research scheme proposed by Arnold (1983), which means that I will examine the relationship between design and performance (the performance gradient) and between performance and fitness (the fitness gradient). Because of the complexity of this task, I will restrict myself to one species of the Lacertidae: the Canary Island lizard Gallotia galloti. At the design level of the males of this species, I will measure some morphological (morphometry, coloration, femoral pores,...) and physiological (immune system, hormones) characteristics. Also many kinds of performance will be measured: locomotion, bite force, fighting ability and parasite load on a primary level and territorial quality, foraging success and mating success on a secondary level. Because Gallotia galloti is an ectotherm organism, body temperature is a key factor in this scheme and will have an important influence on all kinds of performance. All these design and performance parameters will be linked with each other and with survival and reproductive success, on the basis of theories and hypotheses concerning natural selection s.s., intrasexual selection (competition between males) and intersexual selection (female mate choice). These hypotheses and supposed links will be tested by correlative analyses based on field data, supplemented with laboratory experiments. During the field study (taking up several months a year on Tenerife), males will be marked to allow permanent identification and the following data will be collected: morphometry (snout vent length, body mass, head size, limb length); area of the blue chin spot; blood samples (in order to determine testosterone levels and immunocompetence); parasite load, courting behaviour and copulations; aggressive behaviour towards other males and contests; territorial area and quality. These data will allow us to investigate the link between, for instance, territorial quality and mating success or between head size and dominance. Annual survival will be estimated with capture-recapture techniques. Laboratory experiments will include: - Tests of locomotor capacity (sprint speed, endurance and manoeuvrability) in order to investigate biomechanical relationships between body shape and function, to reveal possible trade-offs between different locomotion patterns and to estimate the effect of locomotor capacity on survival. - Staged contests between males to identify parameters affecting fighting ability. The following parameters will be tested: body size, head size (relative to body size), body temperature, testosterone level, area of the blue chin spot, residence and prior experience. - Tests of female mate choice, based on visual and/or chemical signals. - Phenotypic engineering with testosterone in order to test the immunocompetence handicap hypothesis (Folstad & Karter, 1992).

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Van Damme Raoul
• Fellow: Scheers Hans

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Several major radiations of amphibians have evolved from terrestrial ancestors. Some lineages have further developed the terrestrial design while others have derived an aquatic habit. Among frogs, constraints imposed by ancestral traits have significantly affected the evolution of locomotor mode: almost every frog group has evolved very specialised morphological adaptations for a saltatory (jumping) locomotion. Despite the apparent conflicting demands of jumping and swimming in frogs, hypotheses concerning the energetic trade-offs of these locomotor modes have never been explored. For example, swimming can be considered to be a costly activity because of the intermittent nature of this mode. However, slowly swimming frogs frequently maintain a continuous motion, which according to theory should reduce these costs. In short, the main purpose of this study is to quantify energetic costs of swimming and determine the mechanical differences between jumping and swimming in a model species of frog (Rana esculenta). These data will provide important insights into the origin of a possible trade-off between swimming and jumping in anurans.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Nauwelaerts Sandra

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The evolution of habitual bipedalism is a key event in the evolution of early hominids. Two major theories about `the how and why' of the involved evolutionary changes exist. Both are based on a limited set of paleontological data only. The first theory, the terrestrial theory, suggests that habitual bipedalism evolved from terrestrial quadrupedal locomotion. The resemblance between the scaphöids of apes and early hominids, for instance, has recently been used to argue that bipedalism arose from quadrupedal knuckle walking. The second theory, the arboreal theory, suggests that arborealism is preadaptive to habitual bipedalism. This theory also builds on indirect morphological facts and no convincing evidence is found thus far. On the other hand, it can be argued that both arboreal climbing and terrestrial bipedalism require propulsive forces to be mainly delivered by the hind limbs, or that climbing, like bipedal walking, involves an independent use of fore and hind limbs. Again, however, the conclusive force of such functional considerations remains limited. In order to evaluate evolutionary theories on locomotion more decisively, profound biomechanical analysis is required. Since experimental studies on extinct species are impossible, comparative kinesiological research on extant model species, preferable primates, can offer a way out. In that case it is essential that all locomotion types central to the theories to be tested, belong to the natural repertoire of the model species. To date, only few biomechanical studies on primates address arboreal locomotion. Therefore, this project wants to evaluate the arboreal theory through kinesiological analysis of the climbing locomotion in the bonobo (Pan paniscus). A comparison between the manner in which the musculo-skeletal system functions in quadrupedal and bipedal climbing, as well between climbing and terrestrial locomotion will be made. This species fulfils the essential condition mentioned above: in nature, arboreal as well as terrestrial quadrupedalism and bipedalism are observed. In addition, morphometric and paleo-ecological arguments support this choice of model species. In practice, an integrated experimental set-up will be built, from which 3D-kinematic data (whole body or details of hands and feet) of arboreal locomotion can be obtained simultaneously with substrate reaction forces (either for the whole body or feet and hands separately). When combined with morphometric information (linear dimensions as well as inertial properties) these data will allow us to estimate through inverse dynamic modelling, the manner in which the musculo-skeletal system functions. Mechanical locomotor costs can be calculated. A variety of conditions (different slopes and diameters of substrate) will be compared. The results obtained for quadrupedal and bipedal arboreal performance will be integrated with the data obtained from a parallel study dealing with terrestrial locomotion. This must allow for a reliable evaluation of the arboreal theory.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Schoonaert Kirsten

Research team(s)

Project type(s)

• Research Project

Abstract

The evolution of a terrestrial feeding mode and the origin of the amniote skull structure have undoubtably been key phenomena in the evolution of vertebrates. Althoug there is a substantial body of work, dealing with the craniocervical structure and feeding systems in mammals and birds, relatively little is known about these systems in lower tetrapods. Still, the study of these basal groups is essential to gain insights in the evolutionary processes that shaped the feeding system. Within the scope of this post-doc two topics are proposed for further study. First, the neuromotor basis of feeding in lizards will be examined. Here, emphasis will be placed on investigations into the presumed stereotypy of feeding motor patterns. Additionally we will investigate the presence, prevalence and importance of feedback systems in the evolution of lizard feeding systems. The second question I would like to address within the scope of this post-doc concerns the ecomorphological relations of the feeding apparatus in lizards. Using a broad, comparative approach within a strict phylogenetic context, we will investigate the importance of several performance parameters of the feeding system in lizards. This should allow us to identify those elements which played a critical role in the evolutionary diversification of the feeding system in lizards. The techniques and statistical methods that will be used to analyse these types of data (which will be learned in the lab. of Dr. D. Irschick, Tulane University - New Orleans), will eventually also be used to analyse the evolution of neuromotor control of the feeding system in lizards.

Researcher(s)

• Promoter: Aerts Peter
• Promoter: De Vree Frits
• Fellow: Herrel Anthony

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Within a few months, infants adopt the co-ordination required for a stable habitual walk. Two ways of analysis are open to study this development. In the phenomenological approach (dynamical systems approach), the complex system is reduced to a few variables considered to be the collective result of the dynamical behaviour of all of the systems components. Analysis of variance of the cyclic behaviour of these variables offers insight in the developmental processes (Thelen & Smith, 1994; Clark, 1997). In case of the mechanistic approach, insight is gained in the causes underlying the cyclic behaviour through detailled analysis of the structure and biomechanics of the locomotor system. The phenomenological and mechanistic approaches are to be considered as highly complementary in understanding the fenomenon of motor development. Most of the longitudinal studies investigating the early development of independent walking, preferably used the phenomenological approach, hereby not taking into account a few exceptions (Sutherland et al.,1980; Grimshaw et al.,1998). Our project tends to gain insight in the biomechanical causes underlying the observerd changes in children learning to walk. As mentioned in literature, independent walking requires the combination of balance and the generation of a propulsive movement. We tend to investigate how this challenge is realised by the morphology of a toddler, wich differs from the adult morphology, by means of detailed 3D- kinematical analysis, together with measurement of the 3D-ground reaction forces, the pressure distribution pattern under the feet (registrated with high spatial and temporal resolution) and perhaps electromyographical registration. Attention is paid to the dynamics of the the center of mass and the body segments. Kinetics and energetics will teach us how much energy it costs to walk. Joint-moment are used to calculate wich joints produce energy and where the energy disappears. We will also study the forces and pressures under the feet and the pathway of the center of pressure. In combination with the ground reaction forces, this information allows us to determine the stability in the joints. Attention must also be paid to the occasional trials when the child fails to stay upright. Wich parameter differs and make the infant lose his balance? Amongst children the variability in gait patterns is large, therefore it is not our goal to define an average gait pattern of 'the new walker'. Rather we want to determine some general trends in the development of independent walking.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

Project type(s)

• Research Project

Abstract

The question can be asked why bipedalism has only become obligatory in the genus Homo. Indeed, all recent genera of the Hominoidea show in more or less degree bipedalism in their locomotory repertoire. Hereby it attracts the attention that the closest relatives of man make only use in a limited degree of bipedal locomotion, despite the large morphological and morphometrical similarity. Gibbons, the furthest relatives of man, are in contrast, the most bipedal of all non-human primates and this despite their specific adaptations to an other type of locomotion, namely brachiation. The group where the extant Hylobates species belong to, has split off approximately 20 million year ago from the line leading to the Hominidae. It is thus not unlikely that the bipedal locomotion of Hylobates developped independently of this occuring in more recent genera as Pan and Homo. To sustain (or to reject) this hypothesis, we first have to answer the following question: what are the functional morphological and kinesiological differences and similarities between the bipedalism of Hylobatidae and Hominidae? This proposal is an extension of the current FWO-project (G.0209.99) where the locomotion of the bonobo is analysed in an evolutive context. This implicates that this Ph.D. study shall in first instance focus on the kinesiology and morphology of the locomotory apparatus of Hylobates. Although already many studies exit about brachiation in this genus, the kinesiology of the bipedal locomotion has not yet been studied in detail. A profound analysis of the foot structure is an essential complementation, necessary for the interpretation of this biomechanical study. In second instance there will be reverted to the results of the above-mentioned biomechanical research of the bonobo (and human) to conduct the comparison of their bipedal locomotion. Because a detailed study of the foot of Pan paniscus is not a topic of the inter-university FWO-project mentioned, the morphological analysis of the bonobo foot is also included in this Ph.D. proposal.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Vereecke Evie

Research team(s)

Project type(s)

• Research Project

Abstract

Many authors (beginning with Pianka 1966) suggest that an animal has to choose between two highly different foraging strategies: sit and wait foraging (SW), where the animal stands still and waits for a suitable prey to pass by, and active foraging (AF), where the predator actively looks for the suited food. It is often supposed (among others by McLaughlin 1989) that each foraging strategy goes with a series of morphological, behavioural and ecological characteristics (like acceleration capacity, stamina, muscle composition, daily energy demands, diet, prey detection, anti-predator behaviour, habitat choice and thermoregulation). This is called the 'syndrome hypothesis'. Such dichotomy in foraging strategy and the correlated characteristics has been very popular in herpetology for a long while, although there is only little empirical evidence. Even a consensus about the quantitative characterization of an animal as SW or AF doesn't exist. It is suggested recently (see for example Perry 1999) that the dichotomy is false and that there is in fact a continuity in foraging strategies. Further were the fylogenetic relations often not taken in account in the many studies that confirmate the syndrome hypothesis. Therefore, the value of the eventually found differences can not properly determined. This study will evaluate how, within the family Lacertidae, the foraging mode is correlated with characteristics on different levels (stamina, acceleration capacity, ratio red muscle fibers/white muscle fibers in the locomotion apparatus, diet, habitat choice, chemoreceptory capacity), among others with the intention of evaluating the syndrome hypothesis. The phylogeny of the family is relatively well established, so that the interspecific comparisons can take place in an explicitely phylogenetic context. Finally, the found results could give insight in the coevolution of the studied characteristics.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Verwaijen Dave

Research team(s)

Project type(s)

• Research Project

Abstract

This research project deals with the relation between morphological form and function. In the case of musculo-skeletal systems, function is mainly coupled to mechanical interactions with the environment (in a broad sense). Special attention is paid to the construction, function and evolution of the feeding apparatus in vertebrates.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Our project aims to study the hypertrophic development of the lower jaw musculature in some eel-like catfisches of the family Clariidae. The following aspects will be studied : a) detailed morphological analysis on the microscopical level b) comparative morphometric analysis of external measures c) analysis of the performance ability d) carrying out experiments whereby the preference of fishes for different types of prey can be investigated e) ecological study of the diet and parameters of the habitat choice f) systematic-taxonomic characterization of the species g) a functional-morphological study.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Several major radiations of amphibians have evolved from terrestrial ancestors. Some lineages have further developed the terrestrial design while others have derived an aquatic habit. Among frogs, constraints imposed by ancestral traits have significantly affected the evolution of locomotor mode: almost every frog group has evolved very specialised morphological adaptations for a saltatory (jumping) locomotion. Despite the apparent conflicting demands of jumping and swimming in frogs, hypotheses concerning the energetic trade-offs of these locomotor modes have never been explored. For example, swimming can be considered to be a costly activity because of the intermittent nature of this mode. However, slowly swimming frogs frequently maintain a continuous motion, which according to theory should reduce these costs. In short, the main purpose of this study is to quantify energetic costs of swimming and determine the mechanical differences between jumping and swimming in a model species of frog (Rana esculenta). These data will provide important insights into the origin of a possible trade-off between swimming and jumping in anurans.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Nauwelaerts Sandra

Research team(s)

Project type(s)

• Research Project

Abstract

The aim of the project is to develop an integrated apparatus for the measurement of foot pressure profiles and ground reaction forces during locomotion. The latter can be acquired (a) for the vertical component, by integrating the local pressures under the foot and (b) for the lateral and fore-aft components, by means of separate force sensors. The foot pressure profiles will be acquired by means of pressure mats, based on resistive elastomer, that measure at very high spatial (> 3 sensors cm-1) and temporal (up to 500 Hz) resolution. An integration of hard- and software will strongly facilitate a biomechanical analysis of locomotion, both for clinical and scientific applications.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

An important aspect of hominisation was the development of habitual bipedalism. The ultimate explanation is still controversial. The study of the locomotion of extant closely related model-organisms offers an useful research tool in this context. This project aims at the biomechanica! analysis of locomotion in the bonobo (morphometrically best resembling the early hominids) and at the inte-gration of the obtained data with those available for humans.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

It is often assumed that biological evolution will inevitably lead, through the process of natural selection, to an optimal design for each ecological function. However, the adaptation process may be impeded or slowed down by constraints or trade-offs, obscuring the relationship between form and function. In theory, the adaptation process involves four stages: genetic variation may lead to variation in design which in turn may cause differences in performance for a given function, ultimately causing differential fitness (survival/reproductive success). Constraints may operate on all relationships between the stages. Here we propose an integrated and experimental study of the complete adaptation process that tackles all stages and relationships in three model species for a single function, locomotion. Locomotion is ecologically relevant since it is essential for many biological processes such as feeding, escaping from predators and dispersal. Performance can be easily quantified in terms of speed, acceleration, endurance and manoeuvrability. The model species are an insect, an amphibian and a reptile. Locomotory performance of these ectothermic animals is strongly temperature-dependent. Temperature is used as a model for the importance of fluctuating environmental parameters in evolution. The role of trade-offs in adaptation is investigated by considering interactions between different locomotory components, such as speed vs. endurance. The specific research questions are the following: (1) - What is the variation in performance? Do trade-offs exist? How does temperature influence performance? (2) - What are the mechanistic causes of variation in performance (morphological, physiological, kinematic)? (3) - Is some of the variation in performance genetically determined? (4) How does variation in performance translate to differences in survival or reproductive success? To answer these questions, the three model species will be raised in the laboratory under different temperature regimes, and performance for several locomotory components will be measured and may be followed throughout development. This is mainly done by digitization of high-speed video registrations of moving test animals and numerical analysis of the quantitative data. The obtained data on variation in performance can be correlated to parameters of design, resulting from morphometric, morphological and kinesiological research. The importance of genetic variation is assessed by measuring performance and design parameters in individuals with known relatedness (parent/offspring, sibs, half-sibs) obtained from breeding experiments (quantitative genetics). The question whether variation in performance also implies variation in fitness, is determined by comparing survival chances in laboratory or field conditions with a given predator pressure (better performing individuals are expected to have a higher chance to escape), by measuring pairing success or by directly counting the number of offspring. To achieve this research programme, the competence and expertise of three research groups of the UIA are joined. The laboratories of Functional Morphology, Ethology and Animal Ecology each have experience in research on particular aspects of the general scheme, have broad experience with research on, and raising of, model species, and most of the required facilities are present. The requested budget includes only incubators for temperature-controlled breeding experiments. The very labour-intensive nature of most of the research aspects involved in this proposal, explains why most of the requested budget is reserved for taking on additional scientific and technical personnel.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Matthysen Erik
• Co-promoter: Van Damme Raoul

Research team(s)

Project type(s)

• Research Project

Abstract

Several major radiations of amphibians have evolved from terrestrial ancestors. Some lineages have further developed the terrestrial design while others have derived an aquatic habit. Among frogs, constraints imposed by ancestral traits have significantly affected the evolution of locomotor mode: almost every frog group has evolved very specialised morphological adaptations for a saltatory (jumping) locomotion. Despite the apparent conflicting demands of jumping and swimming in frogs, hypotheses concerning the energetic trade-offs of these locomotor modes have never been explored. For example, swimming can be considered to be a costly activity because of the intermittent nature of this mode. However, slowly swimming frogs frequently maintain a continuous motion, which according to theory should reduce these costs. In short, the main purpose of this study is to quantify energetic costs of swimming and determine the mechanical differences between jumping and swimming in a model species of frog (Rana esculenta). These data will provide important insights into the origin of a possible trade-off between swimming and jumping in anurans.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Nauwelaerts Sandra

Research team(s)

Project type(s)

• Research Project

Abstract

To date, terrestrial locomotion in birds has received little attention. In this project, the terrestrial locomotion of the magpie is analysed. The results of a morphological-morphometrical analysis combined with a kinesiological study (kinematics, electromyography, ground reaction forces) and the determination of mechanical characteristics of muscle, bone, tendon will be compilated in a mathematical locomotion model for the magpie. By means of this model hypothesis (energetical or mechaninal reasons for gait transition) will be evaluated. In a last stage, the generality of the model will be examined. The birds which will be used for this will be phylogenetically and ecologically related to magpies.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Verstappen Myriam

Research team(s)

Project type(s)

• Research Project

Abstract

This research project deals with the relation between morphological form and function. In the case of musculo-skeletal systems, function is mainly coupled to mechanical interactions with the environment (in a broad sense). Special attention is paid to the construction, function and evolution of the feeding apparatus in vertebrates.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

Functional analysis of the ecological animal functions such as locomotion and the intake of food is a very important part of research in various domains as biomechanics, functional morphology and eco-morphology. Digital image registration can be used as input for mechanical model analysis.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

To date, terrestrial locomotion in birds has received little attention. In this project, the terrestrial locomotion of the magpie is analysed. The results of a morphological-morphometrical analysis combined with a kinesiological study (kinematics, electromyography, ground reaction forces) and the determination of mechanical characteristics of muscle, bone, tendon will be compilated in a mathematical locomotion model for the magpie. By means of this model hypothesis (energetical or mechaninal reasons for gait transition) will be evaluated. In a last stage, the generality of the model will be examined. The birds which will be used for this will be phylogenetically and ecologically related to magpies.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Verstappen Myriam

Research team(s)

Project type(s)

• Research Project

Abstract

Via the integration of functional morphology and functional ecology, it will be examined how differences in morphology translate into differences in biological performance capabilities. Hereto, details of dynamic performance and morphological analyses will be fed into computer models. Thus, the mechanistic bases of observed variation and potential trade-offs between biological functions will be traced. Finally, heritability of, and genetic correlations between morphology and performance will be estimated. This study programme will be applied to locomotion in lacertid, and feeding in agamid lizards.

Researcher(s)

• Promoter: De Vree Frits
• Co-promoter: Aerts Peter
• Co-promoter: Van Damme Raoul

Research team(s)

Project type(s)

• Research Project

Abstract

Anguilliform swimming is characterised by a backward travelling kinematical wave that must have certain physical characteristics in order to deliver the needed propulsion. To a large extent, these are determined by the various functions of the axial muscles (delivering netto power, stiffening) who differ in function of time and position along the body. A detailed analysis of the muscle function by means of kinematical, electromyographical and muscle-physiological techniques will not only gain an insight in the widespread mechanism of anguilliform swimming, but also in the functioning of complex biomechanical systems.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

Biomechanical parameters such as force, pressure, acceleration, displacement and velocity can be transmitted in continuous analogous signals by means of transducers and amplifiers. A 8-channel, 12 bit digital scope-board (Imtec Messteam PCDAB512) with large memory (2 MByte) is used for further numerical processing.

Researcher(s)

• Promoter: Aerts Peter

Research team(s)

Project type(s)

• Research Project

Abstract

This research project deals with the relation between morphological form and function. In the case of musculo-skeletal systems, function is mainly coupled to mechanical interactions with the environment (in a broad sense). Special attention is paid to the construction, function and evolution of the feeding apparatus in vertebrates.

Researcher(s)

• Promoter: De Vree Frits
• Fellow: Aerts Peter

Research team(s)

Project type(s)

• Research Project