EXPERIMENTAL EVOLUTION

Abstract : Many evolutionary hypotheses consist of predictions about what specific adaptations - behavioural, physiological or morphological - might be expected to evolve under a given scenario. The use of optimization models in evolution has added quantitative rigour to this approach. Traditionally, the approach used for testing such hypotheses has been via the comparative method: to seek correlations, across a large number of species, between character states and environmental variables. In more recent times, people have begun to use laboratory systems to rigorously test evolutionary hypotheses by subjecting replicate populations to specific selection regimes under carefully controlled environmental conditions, and then tracking these populations over generations to actually observe the set of traits that evolves in response to that particular selection regime. This approach, though time consuming and labour intensive, yields interesting insights into the subtlety of the process of adaptive evolution through natural selection, and the results from many such studies suggest that the confidence we repose in simple optimization arguments and grand generalizations in evolutionary biology is likely misplaced. In this talk, I will discuss some of my own work on fruit-flies subjected to selection for adaptation to larval crowding, and for faster egg to adult development, as a means of illustrating the strengths of experimental evolutionary biology when one's aim is to study evolution as a dynamic process, and some of the pitfalls inherent in the optimization approach.