Dr. Pavitra Muralidhar, University of Chicago

Pavitra Muralidhar, Ph.D., Assistant Professor in Ecology & Evolution at University of Chicago

Twitter

Abstract

Sexual selection is a key evolutionary process that shapes patterns of genetic and phenotypic variation within populations and across taxa. I will discuss two projects that examine the causes and consequences of sexual selection within and between species. The first considers the evolution of mate preferences for costly displays. There are two broad mechanisms for how such preferences evolve: Fisher’s runaway process and Zahavi’s handicap principle. While these mechanisms are often portrayed as competing alternatives, they will in fact necessarily act simultaneously whenever handicap displays are heritable. We take advantage of the flexibility of evolutionary simulations to investigate the relative importance and overlap of these two mechanisms in the evolution of costly signals. The second project considers the role of sexual selection in the enforcement of species boundaries, exploring an indirect genetic mechanism through which mating preferences for conspecifics can enhance post-zygotic barriers to gene flow between species, specifically by increasing ancestry variance and thus the efficiency of post-zygotic selection. Using a combination of mathematical modeling, whole-genome simulations, and data from natural hybrid zones, we show that this “bundling effect” of sexual selection can substantially increase the rate at which introgressed DNA is purged by post-zygotic selection following admixture, thus contributing significantly to the genetic maintenance of species.