Data from: Genetic monitoring and complex population dynamics: insights from a 12-year study of the Rio Grande silvery minnow

The endangered Rio Grande silvery minnow persists as a remnant population in a highly fragmented and regulated arid-land river system. The species is subject to dramatic fluctuations in density. Since 2003, the wild population has been supplemented by hatchery-reared fish. We report on a 12-year (1999 – 2010) monitoring study of genetic diversity and effective population size (Ne) of wild and hatchery stocks. Our goals were to evaluate how genetic metrics responded to changes in wild fish density and whether they corresponded to the number and levels of diversity of hatchery-reared repatriates. Genetic diversity and all measures of Ne in the wild population did not correlate with wild fish density until hatchery supplementation began in earnest. Estimates of variance and inbreeding effective size were not correlated. Our results suggest source-sink dynamics where captive stocks form a genetically diverse source and the wild population behaves as a sink. Nevertheless, overall genetic diversity of silvery minnow has been maintained over the last decade and we attribute this to a well designed and executed propagation management plan. When multiple factors like environmental fluctuation and hatchery supplementation act simultaneously on a population, interpretation of genetic monitoring data may be equally complex and require considerable ecological data.

濒危物种里奥格兰德银小鱼（Rio Grande silvery minnow）作为残存种群存活于高度碎片化且受人为调控的干旱区河流系统中。该物种种群密度会出现剧烈波动。自2003年起，其野生种群通过孵化场繁育的鱼类得到补充。本研究针对1999年至2010年这12年间的野生种群与人工繁育种群的遗传多样性及有效种群大小（effective population size, Ne）展开监测分析，旨在评估遗传指标如何响应野生鱼类密度变化，以及这些指标是否与人工繁育放流个体的数量及多样性水平相匹配。在人工繁育放流补充计划正式启动前，野生种群的遗传多样性与各项有效种群大小指标均与野生鱼类密度无显著关联，且方差有效种群大小与近交有效种群大小的估算值之间不存在相关性。研究结果表明该种群存在源-汇动态（source-sink dynamics）：人工繁育种群构成遗传多样性丰富的源种群，而野生种群则扮演汇种群的角色。尽管如此，在过去十年间，里奥格兰德银小鱼的整体遗传多样性得以维持，我们将这一成果归因于一套设计精良且执行到位的繁育管理方案。当环境波动、人工繁育放流补充等多重因素同时作用于种群时，对遗传监测数据的解读同样会变得复杂，且需要结合大量的生态学数据。