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).