All organisms possess mechanisms to buffer their development against perturbations of environmental or genetic origin, so-called developmental noise. These unknown mechanisms are commonly termed ‘developmental stability’. The combined effect of developmental noise and developmental stability (so-called developmental instability, DI) can be estimated by quantifying the degree at which trait development deviates from its genetic blueprint. The most commonly used procedure to estimate DI involves the measurement of both sides of one or more bilateral traits and calculation of the degree of asymmetric development (fluctuating asymmetry; FA). While theory predicts FA to be a reliable measure of stress and individual quality, reported relationships among FA, stress and quality are notoriously heterogeneous.

This study aims to examine at what extent population and individual levels of DI (measured by FA) are related to environmental and/or genetic (inbreeding) stress levels, and how these factors interact. These questions will be addressed through a combination of laboratory and field experiments on Pararge aegeria, a common butterfly in Flanders, and field observations in a recently-fragmented cloud forest in south-east Kenya. We use morphometric methods that detect differences in shape (asymmetry) by comparing landmark configurations, and genetic analyses of micro-satellite DNA data and allozymes.