Evolution of life-history traits, canalization and reproductive isolation in laboratory populations of drosophila melanogaster selected for faster pre-adult development and early reproduction

Abstract

Experimental evolution provides a good framework for testing evolutionary theories and hypotheses (Rose et al. 1996; Prasad and Joshi 2003). Although field studies have been the traditional mode of investigating natural selection, experimental evolution through laboratory selection offers unique opportunities for understanding the details of the adaptive process and the interactions of micro-evolutionary factors that ultimately shape the evolutionary trajectory of populations. Experimental evolution offers the prospect of studying adaptive responses under well-defined selection pressures that are far less complex than those in the wild, giving the experimenter a relatively better chance of drawing clear inferences about cause-effect networks in adaptive evolution. Moreover, selection regimes can be replicated at the population level, increasing statistical power (Rose et al. 1996). In addition to these, since the population size to be chosen is at the discretion of the experimenter, working with a bigger population size can help effectively minimize confounding effects of genetic drift and inbreeding depression, which is often not possible in case of natural populations (Rose et al. 1996). In experimental evolution, the robustness of the responses to specific selection pressures can also be tested by repeating the selection experiments using sets of populations with different ancestries (Rose et al. 1996).