Abstract
The process of adaptation is a central concept in evolutionary biology for which mechanisms are still poorly understood. Yet, understanding these mechanisms is crucial for predicting evolutionary change. This is also relevant for estimating the effects on biodiversity of global climate change, of which climatic warming is currently the most pressing threat. In addition to ?habitat-tracking? and ?range shifts?, successful adaptation is likely to entail some combination of genetic adaptation and phenotypic plasticity. The tropical seasonal butterfly Bicyclus anynana is eminently suitable for studying the mechanisms of adaptation. This butterfly exhibits high genetic variation as well as adaptive phenotypic plasticity for the suite of traits associated with temperature adaptation. We understand how genetic and phenotypic correlations among life history traits have been shaped by natural selection and how these traits relate to fitness. Moreover, for the key traits underlying the adaptation to the seasonal environments, such as wing pattern, developmental time and egg size, comprehensive knowledge exists on the genetic architecture, including candidate genes, as well as about the developmental and physiological mechanisms. As organisms are already adapted over their distribution to differences in climate, this project will use existing clines with latitude in this butterfly to explore the nature of the genetic and developmental changes that might occur in response to changes in temperature. By comparing populations that differ extensively in their temperature environment and the association with rainfall, we will study the mechanisms of adaptation at three levels. Our research will (i) describe the patterns of the life history traits in terms of genetic and phenotypic variance and covariance matrices; (ii) Explore how these differences are reflected in the physiology, especially in terms of the hormones ecdysone, juvenile hormone and insulin; and, (iii), Determine whether variation in candidate genes identified in previous studies underpin the observed genetic differentiation between the populations for the traits. Application of this fully integrated approach will provide novel insights into the mechanisms of genetic adaptation, and also into the role of phenotypic plasticity herein. Furthermore, it will address the issues of potential constraints in adaptive evolution and the rates of evolutionary change, especially with respect to responses to man-made change.
Netherlands