EvoLunch Seminar: Wen-Juan Ma (Vrije Universiteit Brussel, BE)
EvoLunch Seminar
The evolution of sex chromosomes and sex determination in frogs
" The evolution of sex chromosomes and sex determination in frogs "
Wednesday April 9th 2025
11:00 CET
Mondi 2a, Central Building, ISTA
Hybrid Meeting (for zoom link, email evolunch.seminar@ist.ac.at )
Abstract
| Sex differences in morphology and behavior are ubiquitous across the tree of life. To understand the genomic basis of sex determination and sexual dimorphism, it is crucial to investigate the evolution of sex chromosomes. Model organisms including humans, mice and Drosophila have highly degenerated sex chromosomes, and demonstrate long-term consequences of recombination suppression. The evolutionary forces, genetic and expression-level changes occurring during the early stages of sex-chromosome evolution remain poorly understood. Frogs are fantastic systems to address the pressing questions. By sampling natural populations, lab culturing, molecular evolution and comparative genomic analyses, we found polymorphism in Dmrt1 covaries with sex-determination patterns and sex-chromosome differentiation, and revealed three distinct levels of XY genetic differentiation. Genome-wide Fstshowed a very narrow highest peak including Dmrt1, suggesting a proto-Y with one of smallest XY differentiation in vertebrates. No extensive transcriptional degeneration, nor strong enrichment of transposable elements found on the sex chromosomes. Furthermore, an unprecedented rate of sex chromosome turnover was detected across Ranidae true frogs, indicating turnover helps maintain homomorphic sex chromosomes in this lineage. Finally, my ERC starting grant takes a step further to investigate alternative evolutionary forces, genetic mechanisms, genomic features underlying heteromorphic sex chromosome evolution and turnovers in robber frog lineages. |