Chaotic genetic patchiness without sweepstakes reproduction in the shore crab Hemigrapsus oregonensis

Fine-scale spatial and temporal variation in the genetic composition of benthic recruits, known as chaotic genetic patchiness, is often observed in marine and estuarine species with planktonic larvae. Several explanations have been proposed for chaotic genetic patchiness, including sweepstakes reproductive success, variability in larval source and natural selection. In a survey of the green shore crab Hemigrapsus oregonensis in Bodega Bay, California, allele frequencies at a mitochondrial single nucleotide polymorphism were found to differ significantly among samples of first stage zoeae and between zoeae and adults. Sweepstakes reproductive success is unlikely to be responsible because the fecundity of this species is too low and there was no reduction in genetic diversity among zoeae. In principle, influxes of larvae from genetically distinct populations over 500 km to the north could have caused these differences; however, coalescent estimates indicated that gene flow from these dist...

对于具有浮游幼体的海洋及河口物种而言，其底栖补充群体（benthic recruits）的遗传组成常呈现精细的时空变异，该现象被称为混沌遗传斑块（chaotic genetic patchiness）。针对该现象已有多种解释被提出，包括抽奖式繁殖成功（sweepstakes reproductive success）、幼体来源异质性以及自然选择。在对加利福尼亚州博德加湾（Bodega Bay）的俄勒冈滨蟹（Hemigrapsus oregonensis）开展的调查中，研究人员发现，线粒体单核苷酸多态性（mitochondrial single nucleotide polymorphism）位点的等位基因频率，在第一期状幼体（first stage zoeae）样本间存在显著差异，且状幼体与成体之间的等位基因频率亦存在显著差异。由于该物种的繁殖力较低，且状幼体的遗传多样性未出现降低，因此抽奖式繁殖成功不太可能是导致上述遗传差异的原因。理论上，来自500公里以北遗传分化显著种群的幼体迁入，可能造成了这些差异；然而，溯祖估计（coalescent estimates）结果显示，来自这些远端种群的基因流（gene flow）……