Ludlow A M, Magurran A E
Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB, UK.
Proc Biol Sci. 2006 Oct 7;273(1600):2477-82. doi: 10.1098/rspb.2006.3605.
Post-mating reproductive isolating mechanisms may be among the earliest reproductive barriers to emerge among incipient species. Trinidadian guppy, Poecilia reticulata, populations in the Caroni and Oropouche drainages in Northern Trinidad exhibit marked genetic divergence and provide an ideal system in which to search for these barriers. We inseminated virgin females with equal amounts of sperm from two males, a 'native' male from the female's own population and a 'foreign' male from the other drainage. Artificial insemination ensured that mating order and mate choice did not affect the outcome. Paternities were assigned to the resulting broods using microsatellite markers. As predicted, sperm from native males had precedence over foreign sperm. Moreover, this effect was symmetrical for both drainages. In contrast, we detected no native sperm precedence in controls, in which females received sperm from the same and another population within the same drainage. Our results show that gametic isolation can arise between geographically proximate, though genetically divergent, populations of a single species and highlight the potential role of this process in speciation.
交配后的生殖隔离机制可能是在初始物种中最早出现的生殖障碍之一。特立尼达岛北部卡罗尼河和奥罗普切河流域的特立尼达孔雀鱼（Poecilia reticulata）种群表现出明显的遗传分化，为寻找这些障碍提供了一个理想的系统。我们用来自两个雄性的等量精子对未交配的雌性进行授精，一个是来自雌性自身种群的“本地”雄性，另一个是来自另一个流域的“外来”雄性。人工授精确保了交配顺序和配偶选择不会影响结果。使用微卫星标记确定了后代的父系。正如预测的那样，本地雄性的精子比外来精子更具优势。此外，这种效应在两个流域都是对称的。相比之下，在对照实验中我们没有检测到本地精子的优先性，在对照实验中，雌性接受来自同一流域内相同和另一个种群的精子。我们的结果表明，配子隔离可以在单一物种的地理上相邻但遗传上有差异的种群之间出现，并突出了这一过程在物种形成中的潜在作用。
