Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada; Quebec Centre for Biodiversity Science, Canada.
Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada; Quebec Centre for Biodiversity Science, Canada.
Sci Total Environ. 2020 Oct 20;740:140046. doi: 10.1016/j.scitotenv.2020.140046. Epub 2020 Jun 10.
Genetic diversity is expected to erode in disturbed habitats through strong selection, local extinctions, and recolonization associated with genetic bottlenecks and restricted gene flow. Despite this general prediction and over three decades of population genetics studies, our understanding of the long-term effect of environmental disturbance on local and regional genetic diversity remains limited. We conducted a population genetic survey of the microcrustacean Daphnia across a landscape subject to anthropogenic stressors from a century of industrial mining. At the local scale we found moderate genetic diversity (i.e., low clonal diversity), characteristic of habitat-specific selective sweeps and local extinctions, but high diversity and strong genetic structure at the regional scale despite the shared watershed of many lakes and exceptional dispersal ability of daphniids. Many habitats experienced changes in species assemblages, with the obligate asexual Daphnia pulex lineages-known only to inhabit ponds-dominating disrupted urban lakes. This habitat transition (pond to lake) was likely facilitated by the disruption of ecological barriers maintaining the genomic separation of these young species. Thus, disrupted habitats can exhibit complex and unexpected genetic patterns of local extinctions and recolonizations, followed by habitat transitions, hybridization and potential speciation events that are difficult to predict and should not be underestimated.
遗传多样性预计将在受干扰的栖息地中通过强烈的选择、局部灭绝以及与遗传瓶颈和受限基因流相关的再殖民化而消失。尽管存在这种普遍预测以及三十多年的群体遗传学研究，但我们对环境干扰对本地和区域遗传多样性的长期影响的理解仍然有限。我们对受一个世纪工业采矿人为压力影响的景观中的微型甲壳类动物——水蚤进行了种群遗传调查。在局部尺度上，我们发现了适度的遗传多样性（即低克隆多样性），这是特定于栖息地的选择扫荡和局部灭绝的特征，但在区域尺度上，尽管许多湖泊共享流域且水蚤具有特殊的扩散能力，但其多样性和遗传结构仍很强。许多栖息地经历了物种组合的变化，强制性的无性繁殖的水蚤属的 Daphnia pulex 种群——只栖息在池塘——主导着被破坏的城市湖泊。这种栖息地的转变（池塘到湖泊）可能是由于破坏了维持这些年轻物种基因组分离的生态障碍而促成的。因此，受干扰的栖息地可能表现出复杂和意外的局部灭绝和再殖民化的遗传模式，随后是栖息地转变、杂交和潜在的物种形成事件，这些事件难以预测，不应被低估。
