Data from: Evidence for morphological and adaptive genetic divergence between lake and stream habitats in European minnows (Phoxinus phoxinus, Cyprinidae)

Natural selection drives local adaptation, potentially even at small temporal and spatial scales. As a result, adaptive genetic and phenotypic divergence can occur among populations living in different habitats. We investigated patterns of differentiation between contrasting lake and stream habitats in the cyprinid fish European minnow (Phoxinus phoxinus) at both the morphological and genomic level using geometric morphometrics and AFLP markers, respectively. We also used a spatial correlative approach to identify AFLP loci associated with environmental variables representing potential selective forces responsible for adaptation to divergent habitats. Our results identified two morphotypes between lakes and streams, with lake fish presenting a deeper body and caudal peduncle compared to stream fish. Differences between these morphotypes conformed to a priori predictions concerning biomechanics and swimming performance in lakes versus streams. Moreover, morphological differentiation was found to be associated to several environmental variables, which could affect body and caudal peduncle shape. We found adaptive genetic divergence between these contrasting habitats in the form of a few "outlier" loci (2.9%) whose genetic divergence exceeded neutral expectations. We also detected additional loci (6.6%) not associated with habitat type (lake versus stream), but contributing to adaptive genetic divergence between populations. Specific environmental variables related to trophic dynamics, landscape topography and geography were associated with several neutral and outlier loci. These results provide new insights into the morphological divergence and genetic basis of adaptation to differentiated habitats in European minnows.

自然选择驱动局部适应，即便在极小的时间与空间尺度下也可能发生。据此，栖息于不同生境的种群间可出现适应性遗传与表型分化。我们以几何形态测量法（geometric morphometrics）与扩增片段长度多态性（Amplified Fragment Length Polymorphism, AFLP）标记分别在形态学与基因组学层面，探究了鲤科鱼类欧洲鱥（Phoxinus phoxinus）在湖泊与溪流这两类对比鲜明的生境中的分化模式。此外，我们采用空间关联分析法，识别出与代表不同生境适应潜在选择压力的环境变量相关的AFLP位点。研究结果显示，湖泊与溪流生境中存在两种形态型：相较于溪流个体，湖泊个体的躯体与尾柄更为宽厚。这两类形态型的差异符合针对湖泊与溪流生境中生物力学与游泳性能的先验预测。此外，研究发现形态分化与若干可影响躯体及尾柄形态的环境变量存在关联。我们在这些对比生境间发现了适应性遗传分化：约2.9%的‘异常’位点的遗传分化程度超出中性进化预期。此外，我们还检测到另外6.6%的位点，这些位点虽与生境类型（湖泊vs溪流）无关，但却推动了种群间的适应性遗传分化。与营养动态、景观地形及地理特征相关的特定环境变量，与若干中性位点及异常位点存在关联。本研究结果为欧洲鱥的形态分化以及适应不同生境的遗传基础提供了新的认知。