Extreme heterochiasmy and high rates of sex-reversed recombination result in large yet homomorphic sex chromosomes in the Emei moustache toad.

ABSTRACT: Unlike the highly degenerated sex chromosomes in birds and mammals, many amphibians possess homomorphic sex chromosomes, which may result from high rates of sex chromosome turnover and/or occasional recombination between the X and Y (or Z and W) Chromosomes. Yet, the molecular basis for maintaining homomorphy remains elusive, particularly the power of rare recombination events to arrest sex chromosome divergence. Here, we identified sex chromosomes of the Emei moustache toad and examined potential mechanisms of maintaining homomorphy. Although the sex chromosomes are homomorphic, we observed an extensive region of X-Y genetic differentiation, spanning ∼349 Mb, among the largest known to date in vertebrates. Despite this large size and the assumption that inversions catalyze recombination s

SUBMITTER: Xie S 

PROVIDER: S-EPMC12129018 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature