Developmental instability in relation to stress and fitness in birds and moths studied by the Laboratory of Animal Ecology of the University of Antwerp

Evolutionary and conservation biologists are in need of simple surrogate measures of fitness and the action of stress on fitness components. Fluctuating asymmetry, an estimate of developmental instability, has been suggested to reliably reflect stress and fitness but evidence is highly heterogeneous. This heterogeneity is confirmed by the results we obtained from three different projects at the Laboratory of Animal Ecology that we review in this paper. In seven bird species inhabiting three indigenous cloud forests in Kenya, asymmetry closely related to stress and/or fitness, yet the underlying mechanisms appeared complex. On the other hand, in two moth species the link between asymmetry and both stress and fitness was less clear or even absent. These results call for more large-scale studies in order to identify factors that allow predicting if and when asymmetry reflects stress and/or fitness.