Data from: Genetic diversity and divergence in the fountain darter (Etheostoma fonticola): implications for conservation of an endangered species

The endangered fountain darter Etheostoma fonticola is found only in the Comal and San Marcos rivers in the Guadalupe River basin in central Texas, USA. Comal River fountain darters were believed to be extir- pated following a severe drought in the 1950s and were reintroduced in the early 1970s using 457 darters from the San Marcos River. In this study we used 23 microsatellite loci to describe and evaluate the genetic diversity, population structure and effective population size (Ne) of fountain darters. We also evaluated the genetic effect of the Comal River reintroduction and the influence of low-head dams (dams) on dispersal in both rivers. Bayesian analysis of individual genotypes and Analysis of Molecular Variation supported two distinct populations concordant with the two rivers. Estimates of Ne were much smaller (<10 %) than census size (Nc) in both rivers but did not indicate the populations are at risk of an immediate and rapid loss of genetic diversity. Coalescent-based estimates of the genetically effective number of founders (Nf) for the Comal River averaged about 49 darters and, together with the indices of genetic diversity and the bottleneck test (heterozygosity excess) results, were consistent with a founder event following the reintroduction in the Comal River. Finally, our results regarding the influence of dams on fountain darter dispersal were equivocal and did not support a conclusion. We recommend this issue be examined further as part of the fountain darter recovery program.濒危物种喷泉镖鲈（Etheostoma fonticola）仅分布于美国德克萨斯州中部瓜达卢佩河流域的科马尔河与圣马科斯河。此前认为科马尔河的喷泉镖鲈在1950年代的严重干旱后局部灭绝，并于1970年代早期利用来自圣马科斯河的457尾个体完成重新引入。本研究采用23个微卫星位点（microsatellite loci），对喷泉镖鲈的遗传多样性、种群结构以及有效种群大小（Ne）进行描述与评估。本研究同时评估了科马尔河种群重新引入项目的遗传效应，以及低水头坝（low-head dams）对两条河流中喷泉镖鲈扩散行为的影响。基于个体基因型的贝叶斯分析与分子方差分析结果表明，存在两个与两条河流对应的显著分化种群。两条河流中喷泉镖鲈的有效种群大小估算值均远小于其普查种群数量（Nc）（不足其10%），但并未表明种群正面临快速丧失遗传多样性的即时风险。基于溯祖理论的科马尔河奠基者有效种群数量（Nf）估算值平均约为49尾，结合遗传多样性指数与瓶颈效应检测（杂合子过剩）结果，均支持科马尔河重新引入项目后存在奠基者效应事件。最后，本研究关于低水头坝对喷泉镖鲈扩散行为影响的结果存在歧义，无法得出明确结论。我们建议将该问题作为喷泉镖鲈种群恢复计划的一部分开展进一步研究。