Data from: Restricted gene flow within and between rapidly diverging neotropical plant species

Speciation involves the evolution of traits and genetic differences that contribute to reproductive isolation and the cessation of gene flow, and studying closely related species and divergent populations gives insight into how these phenomena proceed. Here, we document patterns of gene flow within and between two members of a rapid Neotropical species radiation, Costus pulverulentus and Costus scaber (Costaceae). These species co-occur in the tropical rainforest and share pollinators, but are reproductively isolated by a series of prezygotic barriers, some of which show evidence of reinforcement at sympatric sites. Here, we genotype microsatellite markers in plants from eight sites that span the geographical range of both species, including four sympatric sites. We also genotype putative hybrids found at two sympatric sites. We find high levels of genetic isolation among populations within each species and low but detectable levels of introgression between species at sympatric sites. Putative hybrids identified by morphology are consistent with F1 or more advanced hybrids. Our results highlight the effectiveness of prezygotic isolating mechanisms at maintaining species boundaries in young radiations and provide empirical data on levels of gene flow consistent with reinforcement.

物种形成（speciation）指驱动生殖隔离与基因流终止的性状及遗传差异的演化过程；对近缘物种与分化种群开展研究，可助力解析此类现象的具体运作路径。本研究针对新热带区快速物种辐射类群中的两个物种——Costus pulverulentus与Costus scaber（闭鞘姜科Costaceae）——的基因流格局展开系统记录，涵盖物种内部及物种间的基因流模式。该两种物种同域分布于热带雨林中，共享传粉类群，但通过一系列合子前生殖屏障实现生殖隔离；其中部分屏障在同域分布位点呈现出生殖强化（reinforcement）的相关证据。本研究对覆盖两个物种完整地理分布范围的8个采样位点（含4个同域分布位点）的植株进行微卫星（microsatellite）标记基因分型；同时对在2个同域位点发现的疑似杂种开展基因分型分析。研究结果显示，每个物种种群内部存在高度的遗传隔离，而在同域位点的物种间存在低水平但可被检测到的基因渐渗（introgression）。通过形态学特征鉴定的疑似杂种，均符合F1代或更高级别杂种的遗传特征。本研究结果证实了合子前生殖屏障在维持年轻辐射类群物种界限中的有效性，并为与生殖强化相符的基因流水平提供了实证数据。