Graham Carly F, Eberts Rebecca L, Goncin Una, Somers Christopher M
Department of Biology University of Regina Regina SK Canada.
Fish, Wildlife, and Lands Branch, Ministry of Environment Government of Saskatchewan Prince Albert SK Canada.
Evol Appl. 2020 Dec 14;14(4):965-982. doi: 10.1111/eva.13174. eCollection 2021 Apr.
Anthropogenic activities may facilitate undesirable hybridization and genomic introgression between fish species. Walleye () and sauger () are economically valuable freshwater species that can spontaneously hybridize in areas of sympatry. Levels of genomic introgression between walleye and sauger may be increased by modifications to waterbodies (e.g., reservoir development) and inadvertent propagation of hybrids in stocking programs. We used genotyping by sequencing (GBS) to examine 217 fish from two large reservoirs with mixed populations of walleye and sauger in Saskatchewan, Canada (Lake Diefenbaker, Tobin Lake). Analyses with 20,038 (r90) and 478 (r100) single nucleotide polymorphisms clearly resolved walleye and sauger, and classified hybrids with high confidence. F, F, and multigeneration hybrids were detected in Lake Diefenbaker, indicating potentially high levels of genomic introgression. In contrast, only F hybrids were detected in Tobin Lake. Field classification of fish was unreliable; 7% of fish were misidentified based on broad species categories. Important for activities such as brood stock selection, 12 of 173 (7%) fish field identified as pure walleye, and one of 24 (4%) identified as pure sauger were actually hybrids. In addition, two of 15 (13%) field-identified hybrids were actually pure walleye or sauger. We conclude that hybridization and introgression are occurring in Saskatchewan reservoirs and that caution is warranted when using these populations in stocking programs. GBS offers a powerful and flexible tool for examining hybridization without preidentification of informative loci, eliminating some of the key challenges associated with other marker types.
人为活动可能会促进鱼类物种之间不良的杂交和基因组渐渗。大眼狮鲈（）和黑鲈（）是具有经济价值的淡水物种，它们在同域分布区域能够自然杂交。对水体的改造（如水库开发）以及在放流计划中无意间繁殖杂交种，可能会增加大眼狮鲈和黑鲈之间的基因组渐渗水平。我们利用简化基因组测序（GBS）技术，对加拿大萨斯喀彻温省两个同时存在大眼狮鲈和黑鲈混合种群的大型水库（迪芬贝克湖、托宾湖）中的217条鱼进行了检测。通过对20,038个（r90）和478个（r100）单核苷酸多态性位点的分析，能够清晰地区分大眼狮鲈和黑鲈，并以高置信度对杂交种进行分类。在迪芬贝克湖中检测到了F、F以及多代杂交种，这表明基因组渐渗水平可能较高。相比之下，在托宾湖中仅检测到了F代杂交种。鱼类的现场分类并不可靠；基于宽泛的物种类别，有7%的鱼被误识别。这对于诸如亲鱼选择等活动很重要，在现场被判定为纯种大眼狮鲈的173条鱼中有12条（7%）实际上是杂交种，而在被判定为纯种黑鲈的24条鱼中有1条（4%）实际上是杂交种。此外，在现场判定为杂交种的15条鱼中有2条（13%）实际上是纯种大眼狮鲈或黑鲈。我们得出结论，萨斯喀彻温省的水库中正在发生杂交和渐渗现象，因此在放流计划中使用这些种群时需要谨慎。GBS提供了一种强大且灵活的工具，可用于在无需预先鉴定信息位点的情况下检测杂交现象，消除了与其他标记类型相关的一些关键挑战。
