Data from: Polygamy slows down population divergence in shorebirds

Sexual selection may act as a promotor of speciation since divergent mate choice and competition for mates can rapidly lead to reproductive isolation. Alternatively, it may also retard speciation since polygamous individuals can access additional mates by increased breeding dispersal. High breeding dispersal should hence increase gene flow and reduce diversification in polygamous species. Here we test how polygamy predicts diversification in shorebirds using genetic differentiation and subspecies richness as proxies for population divergence. Examining microsatellite data from 79 populations in ten plover species we found that polygamous species display significantly less genetic structure and weaker isolation-by-distance effects than monogamous species. Consistent with this result, a comparative analysis including 136 shorebird species showed significantly fewer subspecies for polygamous than for monogamous species. By contrast, migratory behaviour did not predict genetic differentiation nor subspecies richness. Taken together, our results suggest that dispersal associated with polygamy may facilitate gene flow and limit population divergence. Therefore, intense sexual selection, as occurs in polygamous species, may act as a brake rather than an engine of speciation in shorebirds. We discuss alternative explanations for these results and call for further studies to understand the relationships between sexual selection, dispersal and diversification.性选择（Sexual selection）可作为物种形成的促进因素，因为差异化配偶选择与配偶竞争可快速引发生殖隔离。反之，性选择也可能延缓物种形成：多配偶个体可通过提升繁殖扩散能力来获取更多配偶，而高繁殖扩散率会增强基因流，进而降低多配偶物种种群的分化程度。本研究以遗传分化与亚种丰富度作为种群分化的替代指标，检验多配偶制对滨鸟物种分化的预测作用。通过分析10种鸻类共79个种群的微卫星（microsatellite）数据，研究发现相较于单配偶制物种，多配偶制物种的遗传结构显著更弱，距离隔离效应也更不明显。针对136种滨鸟的比较分析同样验证了这一结果：多配偶制物种的亚种数量显著少于单配偶制物种。与之形成对比的是，迁徙行为无法有效预测遗传分化程度与亚种丰富度。综合来看，本研究结果表明，与多配偶制相关的扩散行为可促进基因流，进而限制种群分化。因此，正如多配偶制物种所呈现的那样，强烈的性选择在滨鸟中可能扮演物种形成“制动器”而非“引擎”的角色。本研究还讨论了针对该结果的其他潜在解释，并呼吁开展更多研究以厘清性选择、扩散与物种分化之间的关联。