Laboratory of Genetics Ichthyology, University of Girona (UdG), ES-17071 Girona, Spain.
Department of Zoology, Genetics and Physical Anthropology, Faculty of Veterinary, University of Santiago de Compostela (USC), ES-27002 Lugo, Spain.
Genes (Basel). 2022 Jan 28;13(2):255. doi: 10.3390/genes13020255.
Brown trout ( L.) populations have been restocked during recent decades to satisfy angling demand and counterbalance the decline of wild populations. Millions of fertile brown trout individuals were released into Mediterranean and Atlantic rivers from hatcheries with homogeneous central European stocks. Consequently, many native gene pools have become endangered by introgressive hybridization with those hatchery stocks. Different genetic tools have been used to identify and evaluate the degree of introgression starting from pure native and restocking reference populations (e.g., * locus, microsatellites). However, due to the high genetic structuring of brown trout, the definition of the "native pool" is hard to achieve. Additionally, although the * locus is useful for determining the introgression degree at the population level, its consistency at individual level is far from being accurate, especially after several generations were since releases. Accordingly, the development of a more powerful and cost-effective tool is essential for an appropriate monitoring to recover brown-trout-native gene pools. Here, we used the 2b restriction site-associated DNA sequencing (2b-RADseq) and Stacks 2 with a reference genome to identify single-nucleotide polymorphisms (SNPs) diagnostic for hatchery-native fish discrimination in the Atlantic and Mediterranean drainages of the Iberian Peninsula. A final set of 20 SNPs was validated in a MassARRAY® System genotyping by contrasting data with the whole SNP dataset using samples with different degree of introgression from those previously recorded. Heterogeneous introgression impact was confirmed among and within river basins, and was the highest in the Mediterranean Slope. The SNP tool reported here should be assessed in a broader sample scenario in Southern Europe considering its potential for monitoring recovery plans.
在最近几十年中，为了满足钓鱼需求和抵消野生种群减少的影响，已经向河流中重新放养了许多褐鳟（L.）。数以百万计的具有同质中欧种群的孵化场中的可育褐鳟个体被释放到地中海和大西洋的河流中。因此，许多本地基因库因与这些孵化场种群的渐渗杂交而受到威胁。已经使用了不同的遗传工具来识别和评估从纯本地和重新放养的参考种群（例如，位点，微卫星）开始的渐渗程度。但是，由于褐鳟的遗传结构高度复杂，因此很难定义“本地库”。此外，尽管位点可用于确定群体水平的渐渗程度，但它在个体水平上的一致性远非准确，尤其是在几代人被释放之后。因此，开发一种更强大且更具成本效益的工具对于适当监测以恢复褐鳟的本地基因库至关重要。在这里，我们使用 2b 限制位点相关 DNA 测序（2b-RADseq）和 Stack 2 与参考基因组结合，以识别在伊比利亚半岛的大西洋和地中海流域中用于区分孵化场和本地鱼类的单核苷酸多态性（SNP）。通过使用与先前记录的样本相比具有不同渐渗程度的样本，将一组最终的 20 个 SNP 在 MassARRAY®系统中进行基因分型的 SNP 验证，并与全 SNP 数据集进行对比。证实了河流流域之间和内部的异质渐渗影响，在地中海斜坡中最高。考虑到其在监测恢复计划中的潜力，应在更广泛的南欧样本情景中评估此处报告的 SNP 工具。
