The fall 2021 BRS seminar will be on the Zoom Webinar Platform:
Abstract: Sex chromosomes have repeatedly evolved across the tree of life. An important question in sex chromosome research is why do some sex chromosomes undergo extensive recombination suppression and degeneration while others remain largely undifferentiated. Using whole genome and transcriptome sequencing data across poeciliids, livebearing fish that include the guppies, I characterized the structure and conservation of sex chromosome systems within the clade. My work has uncovered an extreme heterogeneity across these species in the extent of sex chromosome differentiation and Y decay. I explored the causes and consequences of this remarkable interspecific variation in sex chromosome evolution. Analyzing allele segregation patterns from pedigree data, I found that incomplete recombination events prevent some Y chromosomes from decaying. In another system, profound Y degeneration has led to the evolution of complete dosage compensation, the first such case identified in fish, and faster rates of coding sequence evolution on the X chromosome. Taken together, this comparative work has provided novel insights into the mechanisms of sex chromosome evolution.