Data from: Contrasting genetic metrics and patterns among naturalized rainbow trout (Oncorhynchus mykiss) in two Patagonian lakes differentially impacted by trout aquaculture

Different pathways of propagation and dispersal of non-native species into new environments may have contrasting demographic and genetic impacts on established populations. Repeated introductions of rainbow trout (Oncorhynchus mykiss) to Chile in South America, initially through stocking and later through aquaculture escapes, provide a unique setting to contrast these two pathways. Using a panel of single nucleotide polymorphisms, we found contrasting genetic metrics and patterns among naturalized trout in Lake Llanquihue, Chile’s largest producer of salmonid smolts for nearly 50 years, and Lake Todos Los Santos (TLS), a reference lake where aquaculture has been prohibited by law. Trout from Lake Llanquihue showed higher genetic diversity, weaker genetic structure and larger estimates for the effective number of breeders (Nb) than trout from Lake TLS. Trout from Lake TLS were divergent from Lake Llanquihue, and showed marked genetic structure and a significant isolation-by-distance pattern consistent with secondary contact between documented and undocumented stocking events in opposite shores of the lake. Multiple factors, including differences in propagule pressure, origin of donor populations, lake geomorphology, and habitat quality or quantity, may concomitantly explain contrasting genetic metrics and patterns for trout between lakes. We also discussed violations of assumptions that may lead to overestimating Nb . We contend that high propagule pressure from aquaculture may not only increase genetic diversity and Nb via demographic effects and admixture, but also may impact the evolution of genetic structure and increase gene flow, consistent with findings from artificially propagated salmonid populations in their native and naturalized ranges.外来物种向新环境传播扩散的不同路径，可能会对已定殖种群产生截然不同的人口统计与遗传影响。多次被引入南美洲智利的虹鳟（Oncorhynchus mykiss），最初通过人工放流、后期经由水产养殖逃逸实现入侵，为对比这两种传播路径提供了绝佳的研究场景。本研究利用单核苷酸多态性（Single Nucleotide Polymorphisms, SNP）标记组，对智利兰基胡湖——近50年来智利最大的鲑科降海幼鱼生产基地——与托多斯洛斯桑托斯湖（TLS，法定禁止水产养殖的参照湖泊）中的归化虹鳟种群展开分析，发现二者的遗传指标与遗传模式存在显著差异。兰基胡湖的虹鳟种群相较TLS湖种群，展现出更高的遗传多样性、更弱的遗传结构，以及更高的有效繁殖种群数量（Nb）估计值。TLS湖的虹鳟种群与兰基胡湖种群存在遗传分化，且呈现显著的遗传结构与明显的距离隔离模式，这与该湖两岸分别存在已记录与未记录的人工放流事件所引发的二次接触现象相符。多种因素可共同解释两湖虹鳟种群间遗传指标与模式的差异，包括繁殖体压力差异、源种群起源、湖泊地貌特征以及栖息地质量与数量的不同。本研究同时讨论了可能导致有效繁殖种群数量高估的假设违背问题。我们认为，水产养殖带来的高繁殖体压力，不仅可通过人口统计效应与遗传混合提升种群遗传多样性与有效繁殖种群数量，还可影响遗传结构的演化并增加基因流，这与本土及归化区域中人工繁育鲑科种群的相关研究结果一致。