Data from: Testing the link between population genetic differentiation and clade diversification in Costa Rican orchids

Species population genetics could be an important factor explaining variation in clade species richness. Here we use newly generated AFLP data to test whether five pairs of sister clades of Costa Rican orchids that differ greatly in species richness also differ in average neutral genetic differentiation within species, expecting that if the strength of processes promoting differentiation within species is phylogenetically heritable, then clades with greater genetic differentiation should diversify more. Contrary to expectation, neutral genetic differentiation does not correlate directly with total diversification in the clades studied. Neutral genetic differentiation varies greatly among species and shows no heritability within clades. Half of the variation in neutral genetic differentiation among populations can be explained by ecological variables, and species-level traits explain the most variation. Unexpectedly, we find no isolation by distance in any species, but genetic differentiation is greater between populations occupying different niches. This pattern corresponds with those observed for microscopic eukaryotes and could reflect effective widespread dispersal of tiny and numerous orchid seeds. Although not providing a definitive answer to whether population genetics processes affect clade diversification, this work highlights the potential for addressing new macroevolutionary questions using a comparative population genetic approach.

物种种群遗传学或许是解释支系物种丰富度差异的关键因素之一。本研究利用新生成的扩增片段长度多态性（Amplified Fragment Length Polymorphism, AFLP）数据，检验五个物种丰富度差异显著的哥斯达黎加兰科姐妹支系的物种种内平均中性遗传分化是否同样存在差异，我们提出的假设为：若驱动物种种内分化的过程强度具有系统发育可遗传性，则遗传分化程度更高的支系其物种多样化速率也应更快。与预期相悖的是，本研究所涉支系的中性遗传分化与总物种多样化程度并无直接关联。中性遗传分化在不同物种间差异显著，且在支系内部未表现出系统发育遗传性。种群间中性遗传分化的变异有一半可由生态变量解释，而物种水平的性状则解释了最多的变异来源。出乎意料的是，所有物种均未表现出距离隔离效应，但占据不同生态位的种群间遗传分化程度更高。该模式与微观真核生物中观测到的结果一致，这或许反映了兰科植物微小且数量众多的种子具备高效的长距离扩散能力。尽管本研究并未就种群遗传学过程是否影响支系多样化给出确定性结论，但它凸显了利用比较种群遗传学方法解答宏观进化新问题的潜力。