In the remote high-elevation streams and rivers in the northwest of Mexico, there is an endemic and highly diverse group of native trout related to the rainbow trout lineage ( Oncorhynchus mykiss ). Currently, only two species have been formally described from this trout complex, the Mexican golden trout, O. chrysogaster , and the San Pedro Mártir rainbow trout, O. m. nelsoni , but only the former occurs in the Sierra Madre Occidental (SMO). South and north of the O. chrysogaster range, there are other undescribed trout that have been recently discovered. Given the various human impacts on aquatic systems occupied by these Mexican native trout, the lack of taxonomic descriptions and the imminent risk of losing populations without their even being documented, we sought to infer a hierarchical population structure of the Mexican native trout, determine the geographic patterns of genetic diversity and gene flow among them, and identify evolutionarily significant units for a prompt conservation strategy. The allelic diversity across eleven microsatellite loci was used to assess genetic divergences of wild trout collected throughout its range in Mexico. Our results reject the old hypothesis that many of the trout in Mexico are introduced or translocated hatchery-reared rainbow trout and strongly support the new hypothesis of distinct genetic populations and lineages in the northwest of Mexico. According to the different statistical analysis of the genetic data, we distinguish between species and subspecies ( O. chrysogaster , O. mykiss , and O. m. nelsoni ) of the other regional lineages of undescribed trout (northern and southern) inhabiting the SMO. We also found a strong genetic substructure within these large clusters. We propose the presence of seven Evolutionarily Significant Units in the drainage basins of the SMO (two occur in the northern region, four in the southern, and one for the area of distribution of O. chrysogaster ) and one in north-western Baja California. Based in microsatellite data a minimum gene flow among populations is evidenced, resulting the presence the highly divergent populations.

中文翻译：

---

确定墨西哥本地鳟鱼进化重要单位的第一步：微卫星变异评估

在墨西哥西北部偏远的高海拔溪流和河流中，存在着与虹鳟鱼谱系（ Oncorhynchus mykiss ）相关的地方性和高度多样化的本地鳟鱼群。目前，这种鳟鱼群中只有两种被正式描述过的物种，墨西哥金鳟鱼 O. chrysogaster 和圣佩德罗马蒂尔虹鳟鱼 O. m。nelsoni ，但只有前者出现在 Sierra Madre Occidental (SMO)。在 O. chrysogaster 范围的南部和北部，最近发现了其他未描述的鳟鱼。鉴于人类对这些墨西哥本地鳟鱼占据的水生系统的各种影响，缺乏分类学描述以及在没有记录的情况下即将失去种群的风险，我们试图推断墨西哥本地鳟鱼的种群等级结构，确定遗传多样性的地理模式和它们之间的基因流动，并确定进化上重要的单元，以制定及时的保护策略。使用 11 个微卫星位点的等位基因多样性来评估在墨西哥整个范围内收集的野生鳟鱼的遗传差异。我们的结果拒绝了旧假设，即墨西哥的许多鳟鱼是引进或转移孵化场饲养的虹鳟鱼，并强烈支持墨西哥西北部具有不同遗传种群和谱系的新假设。根据对遗传数据的不同统计分析，我们区分了栖息在SMO的其他未描述鳟鱼（北部和南部）区域谱系的物种和亚种（O. chrysogaster、O. mykiss和O. m. nelsoni）。我们还在这些大簇中发现了强大的遗传亚结构。我们建议在 SMO 的流域中存在七个具有进化意义的单元（两个位于北部地区，四个位于南部，一个位于 O. chrysogaster 的分布区域）和一个位于下加利福尼亚州西北部。基于微卫星数据，证明了种群之间的最小基因流，导致存在高度分化的种群。