Stepien Carol A, Murphy Douglas J, Strange Rex Meade
Great Lakes Genetics Laboratory, Lake Erie Center and Department of Environmental Sciences, The University of Toledo, 6200 Bayshore Road, Toledo, OH 43618, USA.
Mol Ecol. 2007 Apr;16(8):1605-24. doi: 10.1111/j.1365-294X.2006.03168.x.
Analysis of population genetic relationships reveals the signatures of current processes such as spawning behaviour and migration, as well as those of historical events including vicariance and climate change. This study examines these signatures through testing broad- to fine-scale genetic patterns among smallmouth bass Micropterus dolomieu spawning populations across their native Great Lakes range and outgroup areas, with fine-scale concentration in Lake Erie. Our primary hypotheses include whether genetic patterns result from behavioural and/or geographical isolation, specifically: (i) Are spawning groups in interconnected waterways genetically separable? (ii) What is the degree of isolation across and among lakes, basins, and tributaries? (iii) Do genetic divergences correspond to geographical distances? and (iv) Are historical colonization patterns from glacial refugia retained? Variation at eight nuclear microsatellite DNA loci are analysed for 666 smallmouth bass from 28 locations, including 425 individuals in Lake Erie; as well as Lakes Superior, Huron, and Ontario, and outgroups from the Mississippi, Ohio, St. Lawrence, and Hudson River drainages. Results reveal marked genetic differences among lake and river populations, as well as surprisingly high divergences among closely spaced riverine sites. Results do not fit an isolation-by-geographical-distance prediction for fine-scale genetic patterns, but show weak correspondence across large geographical scales. Genetic relationships thus are consistent with hypotheses regarding divergent origins through vicariance in glacial refugia, followed by colonization pathways establishing modern-day Great Lakes populations, and maintenance through behavioural site fidelity. Conservation management practices thus should preserve genetic identity and unique characters among smallmouth bass populations.
群体遗传关系分析揭示了当前产卵行为和洄游等过程的特征，以及包括地理隔离和气候变化在内的历史事件的特征。本研究通过检测小口黑鲈（Micropterus dolomieu）在其原生五大湖范围内和外群区域的产卵群体中从宏观到微观尺度的遗传模式来研究这些特征，重点聚焦伊利湖的微观尺度。我们的主要假设包括遗传模式是否由行为和/或地理隔离导致，具体如下：（i）相互连通水道中的产卵群体在基因上是否可分离？（ii）湖泊、流域和支流之间的隔离程度如何？（iii）遗传分化是否与地理距离相对应？以及（iv）冰川避难所的历史殖民模式是否得以保留？对来自28个地点的666条小口黑鲈的8个核微卫星DNA位点的变异进行了分析，其中包括伊利湖的425条个体；以及苏必利尔湖、休伦湖和安大略湖，还有来自密西西比河、俄亥俄河、圣劳伦斯河和哈得逊河流域的外群。结果显示湖泊和河流群体之间存在显著的遗传差异，以及在距离相近的河流位点之间存在惊人的高分化。结果并不符合微观尺度遗传模式的地理距离隔离预测，但在大地理尺度上显示出微弱的对应关系。因此，遗传关系与关于通过冰川避难所中的地理隔离形成不同起源、随后通过殖民路径建立现代五大湖群体并通过行为位点保真度维持的假设一致。因此，保护管理措施应保护小口黑鲈群体之间的遗传特性和独特特征。
