Molecular and Evolutionary Strategies of Meiotic Cheating by Selfish Centromeres

Abstract

Asymmetric division in female meiosis creates selective pressure favoring selfish centromeres that bias their transmission to the egg. This centromere drive can explain the paradoxical rapid evolution of both centromere DNA and centromere-binding proteins despite conserved centromere function. Here, we define a molecular pathway linking expanded centromeres to histone phosphorylation and recruitment of microtubule destabilizing factors in an intraspecific hybrid, leading to detachment of selfish centromeres from spindle microtubules that would direct them to the polar body. We also introduce a second hybrid model, exploiting centromere divergence between species, and show that winning centromeres in one hybrid become losers in the other. Our results indicate that increasing destabilizing activity is a general strategy for drive, but centromeres have evolved distinct strategies to increase that activity. Furthermore, we show that drive depends on slowing meiotic progression, suggesting that a weakened meiotic spindle checkpoint evolved as a mechanism to suppress selfish centromeres.