Drivers of achiasmatic meiosis: sexual antagonism versus heteromorphy-dependent aneuploidy across sex-chromosome divergence.

ABSTRACT: Crossing over during meiosis ensures proper chromosome segregation and promotes genetic diversity. In species with chromosomal sex determination, recombination between sex chromosomes is often reduced or eliminated; yet, the evolutionary forces driving this shift remain debated. One extreme outcome, achiasmatic meiosis, typically completely halts recombination in the heterogametic sex. Here, we use a population genetic model to compare 2 leading hypotheses for the evolution of achiasmy: (1) selection to reduce recombination load from sexually antagonistic alleles and (2) selection to avoid aneuploidy driven by heteromorphic sex chromosomes. We analyze how mutations promoting achiasmy can invade autosomes, X chromosomes, or Y chromosomes under each selective regime. Our results reveal that

SUBMITTER: Barboza A 

PROVIDER: S-EPMC12610934 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature