PT  - JOURNAL ARTICLE
AU  - Pavitra Muralidhar
AU  - Graham Coop
AU  - Carl Veller
TI  - Mate choice enhances post-zygotic barriers to gene flow via ancestry bundling
AID  - 10.1101/2021.09.02.458713
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.09.02.458713
4099  - http://biorxiv.org/content/early/2021/09/02/2021.09.02.458713.short
4100  - http://biorxiv.org/content/early/2021/09/02/2021.09.02.458713.full
AB  - Hybridization and subsequent genetic introgression are now known to be common features of the histories of many species, including our own. Following hybridization, post-zygotic selection tends to purge introgressed DNA genome-wide. While mate choice can prevent hybridization in the first place, it is also known to play an important role in post-zygotic selection against hybrids, and thus the purging of introgressed DNA. However, this role is usually thought of as a direct one: a mating preference for conspecifics reduces the sexual fitness of hybrids, reducing the transmission of introgressed ancestry. Here, we explore a second, indirect role of mate choice as a barrier to gene flow. Under assortative mating, parents covary in their ancestry, causing ancestry to be “bundled” in their offspring and later generations. This bundling effect increases ancestry variance in the population, enhancing the efficiency with which post-zygotic selection purges introgressed DNA. Using whole-genome simulations, we show that the bundling effect can comprise a substantial portion of mate choice’s overall effect as a postzygotic barrier to gene flow, and that it is driven by ancestry covariances both between and within maternally and paternally inherited genomes. Using estimates of the strength of assortative mating in avian hybrid zones, we calculate that the bundling effect of mate choice may increase the amount of purging of introgressed DNA by 40-80%, contributing substantially to the genetic isolation of species.Competing Interest StatementThe authors have declared no competing interest.