Repeated and predictable patterns of ecotypic differentiation during a biological invasion: lake-stream divergence in parapatric Swiss stickleback

The relative importance of ecological selection and geographical isolation in promoting and constraining genetic and phenotypic differentiation among populations is not always obvious. Interacting with divergent selection, restricted opportunity for gene flow may in some cases be as much a cause as a consequence of adaptation, with the latter being a hallmark of ecological speciation. Ecological speciation is well studied in parts of the native range of the three-spined stickleback. Here, we study this process in a recently invaded part of its range. Switzerland was colonized within the past 140 years from at least three different colonization events involving different stickleback lineages. They now occupy diverse habitats, ranging from small streams to the pelagic zone of large lakes. We use replicated systems of parapatric lake and stream populations, some of which trace their origins to different invasive lineages, to ask (i) whether phenotypic divergence occurred among populations ...

生态选择与地理隔离在推动并限制种群间遗传与表型分化的相对重要性，往往并非一目了然。当基因流受限与趋异选择共同作用时，在部分情形下，基因流受限既可能是适应的成因，也可能是适应的结果——而后者正是生态物种形成（ecological speciation）的标志性特征。三刺棘鱼（three-spined stickleback）原生分布区的部分区域中，其生态物种形成过程已得到充分研究。本研究聚焦于该物种新近入侵的分布区，对这一演化过程展开探究。瑞士在过去140年间至少经历了三次涉及不同棘鱼谱系的定殖事件，如今这些棘鱼已占据从小型溪流到大型湖泊远洋带的多样生境。我们采用重复的邻域（parapatric）湖溪种群系统，其中部分种群的起源可追溯至不同的入侵谱系，旨在解答以下问题：(i) 种群间是否发生了表型分化……