Disentangling the genetic effects of refugial isolation and range expansion in a trans-continentally distributed species

In wide-ranging taxa with historically dynamic ranges, past allopatric isolation and range expansion can both influence the current structure of genetic diversity. Considering alternate historical scenarios involving expansion from either a single refugium or from multiple refugia can be useful in differentiating the effects of isolation and expansion. Here, we examined patterns of genetic variability in the trans-continentally distributed painted turtle (Chrysemys picta). We utilized an existing phylogeographic dataset for the mitochondrial control region and generated additional data from nine populations for the mitochondrial control region (n = 302) and for eleven nuclear microsatellite loci (n = 247). We created a present-day ecological niche model (ENM) for C. picta and hindcast this model to three reconstructions of historical climate to define three potential scenarios with one, two, or three refugia. Finally, we employed spatially-explicit coalescent simulations and an approxim...

对于分布范围历史上具有动态变化特征的广布类群而言，过往的异域隔离（allopatric isolation）与分布范围扩张过程，均可对当前的遗传多样性结构产生影响。通过考量从单一冰期避难所（refugium）或多重冰期避难所扩张这两种不同的历史情景，有助于区分隔离与扩张过程各自的效应。本研究针对跨大陆分布的锦龟（Chrysemys picta），分析了其遗传变异模式。我们利用已有的线粒体控制区系统地理数据集，并新增了来自9个种群的两类遗传数据：线粒体控制区数据（样本量n=302）以及11个核微卫星位点（nuclear microsatellite loci）数据（样本量n=247）。我们构建了锦龟当前的生态位模型（ecological niche model, ENM），并将该模型回溯至三种历史气候重建场景，以此界定出分别对应1个、2个或3个冰期避难所的三种潜在历史情景。最后，我们采用了空间显式溯祖模拟（spatially-explicit coalescent simulations）与近似……