Oviposition and microhabitat selection in a butterfly under niche expansion : testing the role of behavioural plasticity and learning

Behavioural plasticity in biological traits is assumed crucial for allowing organisms to cope with a heterogeneity of ecological resources in time and space. However, it is still unclear to what extent different types of plasticity may affect adaptive behaviours to colonize and thrive in landscapes under human-induced rapid environmental change. In this PhD-project, I studied this issue in the Speckled wood (Pararge aegeria), by focussing on oviposition-relate behaviour. This butterfly used to be a forest (edge) species, but recently colonized and expanded niche in anthropogenic, non-forested areas too. By using both experimental findings and insights from the literature, we first explored the function of microclimatic preferences during oviposition site selection in P. aegeria and other Lepidoptera. Next, we tested to what extent microclimatic conditions for larvae differed among forest, agricultural and urban landscapes. For the main research question, we combined a reciprocal transplant experiment with detailed observations in semi-natural conditions to test for effects of ecotype, developmental background and adult experience on several behaviours related to oviposition. Motivation to oviposit was mostly affected by larval experience, whereas search effort and exploration decisions by ecotype origin. Ecotype and early experience effects were largely overruled by adult experience. Females are suggested to be well adapted to find (and learn to find) hygrothermally buffered egg-laying sites. Eco-evolutionary processes like local adaptation and non-random spatial sorting likely explain some of the ecotype-related differences. Our results inform on mechanisms of learning evolution, in particular for insects in changing environments.