Due to geologic processes and recent anthropogenic introductions, patterns of genetic and morphological diversity within the Smallmouth Bass (Micropterus dolomieu), which are endemic to the central and eastern United States (USA), are poorly understood. We assessed genetic and morphological differentiation between the widespread Northern Smallmouth Bass (M. d. dolomieu) and the more restricted Neosho Smallmouth Bass (M. d. velox) where their ranges meet in the Central Interior Highlands ecoregion (CIH). Data from 14 microsatellite loci were used to conduct Structure and principal components analyses to evaluate diversity across populations and screen for hybridization with sympatric Spotted Bass (M. punctulatus). We also tested for morphological differences using five morphometric traits and one meristic trait. We found support for three genetic clusters corresponding to previously described taxonomic variation; five clusters largely corresponding to river systems; and nine clusters representing hierarchical population structure within both ranges. We found evidence of a unique genetic cluster in tributaries of the White River within the Northern Smallmouth Bass range and admixture between the subspecies throughout the Neosho range. We also found evidence of morphological differentiation between subspecies; Neosho Smallmouth Bass exhibited larger head length than Northern Smallmouth Bass relative to total length, and there was a significant interaction of subspecies and orbital length, possibly indicating differential growth patterns between subspecies. Our results reveal multiple levels of divergence, suggesting the CIH harbors greater and more complex Smallmouth Bass diversity than previously thought.

由于地质过程和最近的人为引进，人们对美国中部和东部地区特有的小嘴鲈（Micropterus dolomieu）内的遗传和形态多样性格局知之甚少。我们评估了北部小嘴鲈（M. d。dolomieu ）和限制较严格的Neosho小嘴鲈（M. d。velox）之间的遗传和形态分化，它们的范围在中部内陆高地生态区（CIH）相遇。使用来自14个微卫星基因座的数据进行结构和主成分分析，以评估人群之间的多样性，并筛选与同胞斑点鲈（M. punctulatus）杂交）。我们还使用五个形态特征和一个综合特征测试了形态差异。我们发现支持与先前描述的分类学变异相对应的三个遗传簇。五个集群，主要对应于河流系统；以及代表这两个范围内等级人口结构的九个聚类。我们发现在北小茅斯巴斯山脉范围内的怀特河支流中存在独特的遗传簇，并在整个新潮山脉的亚种之间形成了混合体。我们还发现了亚种之间形态分化的证据。Neosho Smallmouth Bass的头部长度比北部Smallmouth Bass的总长度长，并且亚种和轨道长度之间存在显着的相互作用，这可能表明亚种之间的生长方式不同。