From genes to sex: unraveling the evolutionary genomic footprints and genetic mechanisms underlying rapid sex chromosome turnover

Sex-determining genes and sex chromosomes have been maintained for >150 million years in
mammals and birds, and the Y and W chromosomes are highly degenerated (i.e. lost most functional
genes) and hugely shrunk in size. In sharp contrast, sex chromosomes in amphibians, fishes and
many reptiles are little degenerated and largely identical in size, and have frequent dynamic of birth
and death, aka rapid turnover. It is unknown why sex chromosome evolutionary trajectories differ
dramatically across eukaryotes, and the genetic and evolutionary drivers underlying rapid turnover
remain mysterious. Amphibians are excellent systems for advancing our understanding in the
remarkable diversity of sex chromosome differentiation and genetic mechanism. Building upon our
previous findings of rapid sex chromosome turnover in true frogs, in this proposal we aim to 1)
reveal sex chromosomes and their genetic differentiation dynamics; 2) elucidate the evolutionary
genomic footprints underlying rapid turnover; 3) discover the genetic mechanisms underlying sex
chromosome turnover. Unraveling the genomic footprints and the genetic mechanisms driving
turnover will provide significant insights in understanding the diversity of sex chromosome
evolutionary trajectory across the tree of life. This project will fill an important knowledge gap and
push the conceptual boundary on our understanding of stable sex determination, which was
concluded mainly from model organisms including us humans.