Fluctuating asymmetry (FA), i.e. small directionally random differences between the left and right side of a bilaterally symmetric trait, is a potentially interesting and useful indicator of various forms of stress. Although definitions may vary with different sources in the literature, the underlying developmental mechanism assumes that during growth, the developmental pathway of a trait is disturbed (by the processed named 'developmental noise') and that there may be mechanisms that attempt to limit the effects of these disturbances (the process of 'developmental stability'). The joint effect of noise and stability are known as developmental instability (Dl), where higher instability results in a, on average, higher degree of asymmetry. Many studies have shown or found indications that FA (and thus presumably Dl) increases with environmental (parasites, abiotic factors) and genetic (inbreeding, break-up of coadapted gene complexes) stress (reviewed in several chapters in Polak, 2003). Because it has been suggested that the effects of stress on FA may become apparent before important fitness consequences are observed, FA may act as an 'early warning system' (sensu Clarke, 1995) and may form an important tool to identify populations and/or species that require conservation measures before extintion is inevitable. Although of enormous potential in theory, the practical appliction of FA in general and in a conservation biology context more specifically, has been hampered by the vast heterogeneity in the observed associations between FA and stress. More specifically, the lack of general guidelines that allow to predict if and when - for which species(-groups), forms of stress and morphological traits -FA can be expected to increase with stress, has limited its use and has provoked may debates in the recent literature.
This project aims at investigating the usefulness of FA as bio-marker of the potentially negative effects of inbreeding in two relatively closely related butterfly species (Pararge aegeria and Cymothoe teita). P. aegeria is a relatively common European butterfly while C. teita is a threatened and endemic species of the Taita Hills, Kenia. Both species inhabit woodlands that have become intensively affected by fragmentation and degradation worldwide. P. aegeria will be intensively studied under both controlled lab conditions and in the field. This part of the research will allow us to explore and test some fundamental aspects of factors that affect the F A-heterozygosity association ( details of specific hypotheses follow below). To achieve this, we will (i) perform a breeding experiment under controlled conditions where levels of inbreeding will be manipulated experimentally, (ii) study the FA-inbreeding association in the field, (iii) measure FA for a range of different traits that vary in functional importance and (iv) estimate genetic variation using markers with different levels of selective neutrality (microsatellite vs. allozymes, where for the latter butterflies have to be killed). This type of research can only be performed in species like P. aegeria which is relatively common and can be reared and manipulated easily in the lab. In research on threatened species, like C. teita, experimental possiblilities are limited and one should attempt to limit the impact of the research activities on the organism. Therefore, we will limit research on C. teita to measuring FA through digital fotographs and the estimation of genetic variation using microsatellite markers only, based on DNA amplified from small tissue samples. These two non-invasive and non-lethal methods will first be developed and tested in P. aegeria in the lab and field. The fundamental insights obtained from P. aegeria with respect to the FA-inbreeding associations will allow us to carefully plan the work on C. teita and to evaluate the observed patterns. In this project we specifically aim at addressing a number of fundamental questions w