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.种群遗传学或为解释支系物种丰富度差异的关键影响因素。本研究利用新获取的扩增片段长度多态性（Amplified Fragment Length Polymorphism, AFLP）数据，检验5对物种丰富度差异显著的哥斯达黎加兰科姊妹支系，其物种内平均中性遗传分化是否同样存在差异。我们提出如下假说：若推动物种内分化的过程强度具有系统发育可遗传性，则中性遗传分化更强的支系其物种多样化程度应更高。但研究结果与该假说相悖：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相关性。不同物种间的中性遗传分化差异显著，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约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。出乎意料的是，我们未在任何物种中观测到距离隔离现象，但占据不同生态位的种群间遗传分化程度更高。这一模式与微观真核生物中已报道的结果相符，或可反映出微小且数量庞大的兰科种子具备高效的广泛扩散能力。尽管本研究未能明确解答种群遗传学过程是否影响支系多样化这一问题，但它凸显了采用比较种群遗传学方法探究全新宏观进化问题的潜力。