The terrestrial bromeliad Fosterella rusbyi is endemic to the Bolivian Andes, where it mainly grows on steep, exposed slopes along roadsides and riverbeds in the seasonally dry tropical forest (SDTF) and the mesic montane forest (Yungas) biomes. We hypothesize that allopatric speciation may have been a main driver of diversification in Fosterella since the Miocene and that the scattered distribution of suitable habitats fostered the evolution of the high degree of endemism observed today. To provide further information relating to this hypothesis, we analysed the partition of genetic diversity and the extent of gene flow among natural populations of F. rusbyi using plastid and nuclear microsatellite markers. Nineteen plastid haplotypes were found, but the mean haplotype diversity per population was low. Nuclear microsatellite markers revealed 177 different multilocus genotypes (MLGs), of which 31 occurred in more than one plant. Recurrent MLGs were found in 76 plants that were therefore identified as clones. A considerable deficit of heterozygotes was detected at all nuclear loci. Geographical and genetic distances between populations were only weakly correlated with each other. Genetic divergence between populations was extremely high for both marker classes, suggesting that seed and pollen flow are low, even over short distances. The observed patterns are consistent with our hypothesis that newly available sites are sporadically colonized by one or a few founders, followed by in situ population expansion via vegetative propagation, self-pollination and/or biparental inbreeding, genetic differentiation among persistent populations and, ultimately, allopatric speciation.

中文翻译：

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玻利维亚罗氏沼虾种群之间的强遗传分化

陆地凤梨Fosterella rusbyi是特有的玻利维亚安第斯山，它主要生长在陡峭，裸露的路旁和河床斜坡在季节性干旱热带森林（SDTF）和梅西奇山地森林（永加斯）生物群落。我们假设自中新世以来，异源物种可能是福斯特氏菌多样化的主要驱动力，并且适当栖息地的分散分布促进了今天观察到的高度特有物种的进化。为了提供与该假设有关的更多信息，我们分析了遗传多样性（F. rusbyi）之间遗传多样性的分布和基因流动的程度使用质体和核微卫星标记。发现了十九种质体单倍型，但是每个群体的平均单倍型多样性很低。核微卫星标记揭示了177种不同的多基因座基因型（MLG），其中31种出现在多于一种植物中。在76株植物中发现了复发性MLG，因此将其鉴定为克隆。在所有核基因座上都检测到相当数量的杂合子缺陷。种群之间的地理距离和遗传距离之间的相关性很小。两种标记物种群的遗传差异都很高，这表明即使在短距离内种子和花粉的流量也很低。观察到的模式与我们的假设一致，即一个或几个创建者零星地殖民新的可用站点，然后是通过无性繁殖，自花授粉和/或双亲近交，持久种群之间的遗传分化以及最终的异源物种形成进行原地种群扩展。