Possible glimpses into early speciation: the effect of ovarian fluid on sperm velocity accords with post-copulatory isolation between two guppy populations.

Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm-female interactions (postmating-prezygotic barriers) are arguably the hardest to identify, not least because these are likely to operate at the cellular or molecular level. Yet sperm-female interactions offer great potential to prevent the transfer of genetic information between different populations at the initial stages of speciation. Here we provide a preliminary test for the presence of a putative postmating-prezygotic barrier operating... Mehr ...