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. P...物种形成（speciation）指演化出可引发生殖隔离（reproductive isolation）并阻断基因流（gene flow）的性状与遗传差异，对近缘物种及分化种群开展研究，有助于揭示上述过程的具体进展。本研究针对新热带区快速物种辐射类群的两个成员——螺旋唇闭鞘姜（Costus pulverulentus）与光滑闭鞘姜（Costus scaber，闭鞘姜科Costaceae），记录了其种群内及种群间的基因流模式。二者在热带雨林中共存且共享传粉者，但通过一系列合子前生殖隔离屏障（prezygotic barrier）实现生殖隔离，其中部分屏障在同域分布样地（sympatric site）中表现出生殖强化（reinforcement）的迹象。我们对覆盖两个物种地理分布范围的8个样地（包含4个同域分布样地）中的植株进行了微卫星标记（microsatellite marker）基因分型，同时对两个同域分布样地中发现的推测杂种（putative hybrid）进行了基因分型。研究发现，各物种种内种群间存在高水平的遗传隔离，而同域分布样地中物种间则存在低水平但可检测到的基因渐渗（introgression）。P...