Data from: Anthropogenic hybridization between endangered migratory and commercially harvested stationary whitefish taxa (Coregonus spp.)

Natural hybridization plays a key role in the process of speciation. However, anthropogenic (human induced) hybridization of historically isolated taxa raises conservation issues. Due to weak barriers to gene flow and the presence of endangered taxa, the whitefish species complex is an excellent study system to investigate the consequences of hybridization in conservation. We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW). To evaluate the genetic integrity of each taxon, source and reintroduced populations of NSH and BH, and EW populations were characterized based on two mitochondrial and 17 microsatellite loci. Additionally, we investigated gill raker counts as an adaptive phenotypic trait. Even though clear genetic and phenotypic differentiation confirmed the houtings as separate evolutionarily significant units, admixture analyses revealed an extensive hybrid zone. Hybridizations were introgressive, positively correlated with genetic diversity, and were reflected in the gill raker counts. The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range. Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.自然杂交在物种形成过程中发挥关键作用。然而，历史上生殖隔离的类群发生人为诱导的杂交，引发了诸多保护生物学问题。鉴于基因流屏障较弱且存在濒危类群，白鲑物种复合体是研究杂交对保护影响的理想实验体系。本研究聚焦德国境内3个自然生殖隔离的白鲑类群：曾局部灭绝后被重新引入的濒危溯河洄游性北鲑（North Sea houting, NSH）与波罗的海鲑（Baltic houting, BH），以及商业增殖放流的欧洲白鲑（European whitefish, EW）。为评估各类群的遗传完整性，研究基于2个线粒体基因座与17个微卫星基因座，对北鲑与波罗的海鲑的源种群、再引入种群，以及欧洲白鲑的种群进行了遗传特征解析。此外，本研究将鳃耙数目作为适应性表型性状开展了分析。尽管清晰的遗传与表型分化证实北鲑与波罗的海鲑为独立的进化显著单元（Evolutionarily Significant Unit, ESU），但遗传混合分析结果显示存在大范围的杂交带。此类杂交属于渐渗杂交，与遗传多样性呈正相关关系，且可通过鳃耙数目变化得以体现。相较于北鲑的分布区，波罗的海鲑的分布区呈现出更高的遗传异质性与更强的遗传混合程度。非本地基因型的错误增殖放流是上述观测结果的最优解释，这为濒危的北鲑与波罗的海鲑的保护工作带来了严峻挑战。