Laboratoire de Biologie de la Conservation, Département d'Ecologie et Evolution, Biophore, Université de Lausanne, CH-1015 Lausanne, Switzerland.
Mol Ecol. 2011 Nov;20(21):4490-502. doi: 10.1111/j.1365-294X.2011.05284.x. Epub 2011 Sep 27.
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 levels 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 different morphologies between lakes and streams, with lake fish presenting a deeper body and caudal peduncle compared to stream fish. Body shape variation conformed to a priori predictions concerning biomechanics and swimming performance in lakes vs. streams. Moreover, morphological differentiation was found to be associated with several environmental variables, which could impose selection on body and caudal peduncle shape. We found adaptive genetic divergence between these contrasting habitats in the form of 'outlier' loci (2.9%) whose genetic divergence exceeded neutral expectations. We also detected additional loci (6.6%) not associated with habitat type (lake vs. stream), but contributing to 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.
自然选择驱动着局部适应，甚至可能在小的时间和空间尺度上发生。因此，生活在不同生境中的种群可能会发生适应性的遗传和表型分化。我们分别使用几何形态测量学和 AFLP 标记，在形态和基因组水平上研究了生活在不同湖泊和溪流生境中的鲤鱼科小鱼（欧洲丁鱥）之间的分化模式。我们还使用空间相关方法来鉴定与环境变量相关的 AFLP 基因座，这些环境变量代表了导致适应不同生境的潜在选择压力。我们的研究结果发现湖泊和溪流之间存在不同的形态，与溪流鱼类相比，湖泊鱼类的身体更深，尾柄更短。体型变化符合关于在湖泊和溪流中游泳性能的生物力学的先验预测。此外，形态分化与几个环境变量相关，这些环境变量可能对身体和尾柄形状施加选择压力。我们发现这些对比鲜明的生境之间存在适应性遗传分化，表现为“异常”基因座（2.9%），其遗传分化超过了中性预期。我们还检测到了其他（6.6%）与栖息地类型（湖泊与溪流）无关的基因座，但它们有助于种群之间的遗传分化。与营养动态、景观地形和地理有关的特定环境变量与几个中性和异常基因座相关。这些结果为理解分化生境的形态分化和适应遗传基础提供了新的视角。
