Investigating the Seciation Continuum: Ecology, Reinforcement, and the Evolution of Reproductive Isolation in Timema Stick Insects

Vanderbilt University, Nashville TN

Investigators

Abstract

Speciation is an extended process in which two populations lose the capacity to interbreed and exchange genetic material. At the beginning, restrictions on genetic exchange between the populations is minimal; at the end it is complete. Along the way, the degree of genetic restriction, i.e. reproductive isolation, increases over time. This project uses pairs of populations and species of a group of herbivorous stick insects that vary in their history of isolation and opportunity for gene flow. By evaluating reproductive isolation among dozens of these population/species pairs with respect to two major causes of speciation, either ecological divergence associated with host plant use or geographic separation, this study will investigate the speciation process in unprecedented detail. Speciation is the fundamental evolutionary process that generates biodiversity. Given increased public awareness of, and interest in, biodiversity conservation, understanding speciation should be of public, as well as academic, concern. Findings from this study will provide insights into the conditions under which reproductive isolation is low, a situation that can promote the loss of biodiversity through interbreeding and genetic fusion of previously distinct populations. Additionally, this project will train two graduate students and multiple undergraduates in the conduct of science through participation in this research. Finally, collaboration with a professor of education will provide understanding about how students do (and do not) learn evolutionary concepts, an important issue in contemporary society.