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Possible glimpses into early speciation: the effect of ovarian fluid on sperm velocity accords with post‐copulatory isolation between two guppy populations
Author(s) -
Devigili A.,
Fitzpatrick J. L.,
Gasparini C.,
Ramnarine I. W.,
Pilastro A.,
Evans J. P.
Publication year - 2018
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/jeb.13194
Subject(s) - biology , guppy , reproductive isolation , genetic algorithm , sperm , isolation (microbiology) , zoology , evolutionary biology , ecology , genetics , fishery , population , bioinformatics , fish <actinopterygii> , demography , sociology
Abstract Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm–female interactions (post‐mating–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 post‐mating–prezygotic barrier operating between three populations of Trinidadian guppies ( Poecilia reticulata ), an internally fertilizing fish that inhabits streams with different levels of connectivity across Trinidad. We experimentally evaluate the effect of female ovarian fluid on sperm velocity (a predictor of competitive fertilization success) according to whether males and females were from the same (native) or different (foreign) populations. Our results reveal the potential for ovarian fluid to act as a post‐mating–prezygotic barrier between two populations from different drainages, but also that the strength of this barrier is different among populations. This result may explain the previous finding that, in some populations, sperm from native males have precedence over foreign sperm, which could eventually lead to reproductive isolation between these populations.