How and Why Do Sex Chromosomes Evolve?

Explore the fascinating world of sex chromosome evolution in this comprehensive lecture by Catherine Peichel. Delve into the conservation and diversity of sex chromosomes, examining theoretical models and empirical data. Discover the evolutionary timeline of the threespine stickleback Y chromosome assembly and learn about the three evolutionary strata consistent with known inversions between X and Y chromosomes. Investigate testis-biased gene expression and the candidate sex determination gene in threespine sticklebacks. Compare convergence and divergence in sex chromosome evolution across species. Examine the quartet strategy for sequencing neo-X and neo-Y chromosomes, and analyze differentiation patterns without substantial degeneration. Explore gene tree approaches to determine homology between sex chromosomes and investigate different evolutionary trajectories of homologous Y chromosomes. Discuss ongoing questions in sex chromosome evolution research, including asymmetric reproductive isolation and the search for signatures of sexually antagonistic selection. Gain insights into the ultimate goal of conducting functional tests for sexually antagonistic fitness effects using CRISPR technology.

Intro
Sex chromosome conservation
Sex chromosome diversity
Sex chromosome evolution: model
Sex chromosome evolution: data
Sex chromosome evolution system
Threespine stickleback Y assembly timeline
Threespine stickleback Y assembly!
Three evolutionary strata are consistent with known inversions between X and Y
Testis-biased expression of genes that translocated or duplicated on the Y
Amhy is the candidate sex determination gene in threespine stickleback
Convergence and divergence in sex chromosome evolution
The Stickle Sex Chromosome Team
Quartet strategy to sequence neo-X and neo-Y chromosomes
Differentiation without substantial degeneration on Japan Sea neo-Y
Differentiation without substantial degeneration on blackspotted neo-Y
Gene tree approach to determine whether sex chromosomes are homologous
Different evolutionary trajectories of homologous Y chromosomes
Evolution of Gasterosteus sex chromosomes
Sex chromosome evolution: questions
Japanese species pair
Asymmetric reproductive isolation
Dorsal pricking and dorsal spine length map to the neo-X
Searching for signatures of sexually antagonistic selection on Japan Sea neo-Y
Four candidate peaks in genes associated with psychiatric disorders in humans
Ultimate goal: functional tests for sexually antagonistic fitness effects with CRISPR
Final thoughts