Data from: Genetic and phenotypic differentiation among Galaxias maculatus populations in a Patagonian postglacial lake system

Understanding the influence of landscape features on population differentiation is fundamental to evolutionary biology studies. We examined spatial patterns of genetic and phenotypic variability among Galaxias maculatus populations in a complex of four postglacial lakes in northwestern Patagonia differing in size and connectivity among them. A hierarchical Bayesian analysis grouped the individuals collected from 11 localities into 3 genetic clusters, first defining the populations of the two large lakes and separating the two small lakes in subsequent analysis. Genetic structuring was restricted within large lakes. It is known that the larval stage of Galaxias maculatus migrate to the limnetic zone of Patagonian lakes, possibly exerting an homogenizing effect on gene flow within lakes. Gene flow asymmetry and divergences among lakes can be explained by a combination of landscape characteristics and the presence of predators in the short streams that connect them. Individuals from the small lakes are the most divergent morphologically and genetically. The population in the isolated Redonda Lake, exhibit meristic differences as well, suggesting strong drift and environmental effects. This population is likely to have been isolated following the decline in water level of a paleolake that existed in this region approximately 13.2 kya BP.

解析景观特征对种群分化的影响，是进化生物学研究的核心基础课题。本研究聚焦巴塔哥尼亚西北部由4个冰后湖泊组成的湖群（各湖泊的面积与连通性均存在差异），对其中斑点南乳鱼（Galaxias maculatus）种群的遗传与表型变异空间格局展开分析。研究对11个采样点的个体进行解析，通过分层贝叶斯分析（hierarchical Bayesian analysis）将其划分为3个遗传聚类群：首先区分出两个大型湖泊的种群，后续分析进一步分离出两个小型湖泊的种群，且遗传结构分化仅局限于大型湖泊内部。已知斑点南乳鱼的幼体阶段会洄游至巴塔哥尼亚湖泊的敞水带（limnetic zone），该行为可能对湖泊内部的基因流产生均质化作用。湖泊间的基因流不对称性与分化程度，可通过景观特征与连接湖泊的短小溪流中捕食者的存在情况共同解释。来自小型湖泊的个体在形态学与遗传学上的分化程度最高。孤立的雷东达湖（Redonda Lake）种群同样表现出分节特征差异，暗示存在强烈的遗传漂变与环境选择作用。该种群的隔离可能源于约13.2千年前（13.2 kya BP）该区域存在的古湖泊水位下降。