STEPHEN DE LISLE

For the vast majority of metazoan animals, evolution occurs via selection and adaptation in two distinct groups: males and females. Yet we know little about whether and why independent evolution of the sexes has affected the dynamics of diversification – that is, patterns of speciation and extinction. This project will reconcile the uncertain role that evolutionary divergence between the sexes has played in the origins of diversity.

I posit that independent evolution of the sexes may play a facilitating role in diversification, because sexual monomorphism constrains adaptive evolution when phenotypic optima (niches) are sex specific, together suggesting evolutionary divergence between the sexes may play a key role in both speciation and extinction avoidance. I will test this hypothesis by bridging timescales and approaches to reveal the role of sexual divergence in speciation, extinction, and macroevolution.

First, I will leverage complementary experimental approaches in the lab (Drosophila flies) and in the field (Triturus salamanders) to understand respectively the alignment between natural and sexual selection and the role of divergence into sex-specific niches during the early stages of speciation. Second, I will take a comparative approach using novel trait databases spanning the metazoans to understand the role of sexual dimorphism in contemporary population dynamics, and finally at the macroevolutionary level to understand the role of sexual divergence as a driver of lineage diversification in deep time.

The project will reveal the role that evolution of separate sexes has played in the origins of diversity. If my novel hypothesis is correct, this may be a facilitating role, where evolutionary independence of separate sexes has facilitated diversification into otherwise inaccessible niches.