Mate Choice

Too much alike to be receptive

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Science  15 Dec 2017:
Vol. 358, Issue 6369, pp. 1398-1399
DOI: 10.1126/science.358.6369.1398-a
MHC-similar stallions reduce pregnancy rate in mares.PHOTO: PHOTO-EQUINE/SHUTTERSTOCK.COM

Female choice exerts important selective forces and has shaped many obvious phenotypic traits. Cryptic female choice is choice after insemination and generally has less obvious, but no less important, impacts. Burger et al. showed that cryptic female choice may play a role in a well-known mechanism of mate choice, major histocompatibility complex (MHC) matching. Specifically, they found that in warmblood horses, which are bred for equestrian sport, mares exposed to stallions with dissimilar MHC alleles were more likely to get pregnant than those exposed to MHC-similar males. In this case, pregnancy occurred through artificial insemination with semen from stallions other than those exposed to the females; thus, the effect was driven by physical exposure of the mares to “stimulus” males, rather than by the genetic similarity of the donors.

Proc. R. Soc. B 10.1098/rspb.2017.1824 (2017).

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