Two sexes, one genome: but how?
Males and females of many species often look and behave very differently. However, the two sexes share an almost identical set of genes. So, how do these remarkable sex differences arise? Sex chromosomes are the only region of the genome to differ between females and males, and are predicted to play key roles in the evolution of sex differences. Our research is centered on understanding the genomic and evolutionary processes underlying sex differences, and the manifestation and resolution of sexual conflict.

Origins and turnover of sex chromosomes

Why do new sex chromosomes evolve in the first place? What drives turnover between sex determination systems? We study the evolutionary processes surrounding the formation of sex chromosomes and early stages of divergence. Specifically, why do sex chromosomes stop recombining and how is recombination halted? Species with nascent sex chromosomes, such as groups of fish, reptiles and insects, offer exciting opportunities to answer these questions. 

Recombination history of the sex chromosomes

Recombination suppression catalyzes sex chromosome divergence and triggers distinct evolutionary paths relative to the autosomes. The avian sex chromosomes are ideal to study the dynamics and consequences of halting recombination as all birds originally shared identical Z and W chromosomes, but over millions of years the sex chromosomes have stopped recombining independently in different species.

Sex chromosome degeneration

Lack of recombination on the sex-limited W and Y chromosomes means that loci are locked together in physical linkage and decay through a combination of neutral processes. However, degeneration may be countered by selection for sex-specific fitness, where genes maintained on the W and Y should harbor loci for female and male function respectively. Our research explores the trade-off between sex-specific selection and degradative forces in sex chromosome evolution.

Sexual ecology of the genome

Sex chromosomes are predicted to be hotspots of sexual selection, due to their unequal pattern of inheritance, and are thought to play a particularly important role in sexually dimorphic phenotypes. However, sex chromosomes are often very small in many species and contain only a handful of genes. Therefore, we test theories about the role of sexual conflict and sexual selection in driving multiple facets of evolution across the entire genome.

For a summary of my PhD research please watch my talk at Evolution 2015, Guarujá.

​For more current research please watch my  Jasper-Loftus Hills Young Investigator prize talk at Evolution 2017, Portland.