Department of Biology & Monte L. Bean Life Science Museum, Brigham Young University, Provo, UT 84602, USA.
Mol Ecol. 2009 Mar;18(5):904-18. doi: 10.1111/j.1365-294X.2008.04070.x.
Quaternary glacial cycles have played an important role in shaping the biodiversity in temperate regions. This is well documented in Northern Hemisphere, but much less understood for Southern Hemisphere. We used mitochondrial DNA and nuclear elongation factor 1α intron sequences to examine the Pleistocene glacial impacts on the phylogeographical pattern of the freshwater crab Aegla alacalufi in Chilean Patagonia. Phylogenetic analyses, which separated the glaciated populations on eastern continent into a north group (seven populations) and a south group (one population), revealed a shallow phylogenetic structure in the north group but a deep one in the non-glaciated populations on western islands, indicating the significant influence of glaciation on these populations. Phylogenies also identified the Yaldad population on Chiloé Island as a potentially unrecognized new species. The non-glaciated populations showed higher among population genetic divergence than the glaciated ones, but lower population genetic diversity was not detected in the latter. The two glaciated groups, which diverged from the non-glaciated populations at ~96,800-29,500 years ago and ~104,200-73,800 years ago, respectively, seem to have different glacial refugia. Unexpectedly, the non-glaciated islands did not serve as refugia for them. Demographic expansion was detected in the glaciated north group, with a constant population increase after the last glacial maximum. Nested clade analyses suggest a possible colonization from western islands to eastern continent. After arriving on the continent and surviving the last glacial period there, populations likely have expanded from high to low altitude, following the flood of melting ice. Aegla alacalufi genetic diversity has been primarily affected by Pleistocene glaciation and minimally by drainage isolation.
四次冰期循环对中纬度地区的生物多样性形成起着重要作用。这在北半球有充分的记录，但在南半球则知之甚少。我们使用线粒体 DNA 和核延伸因子 1α 内含子序列来研究更新世冰川对智利巴塔哥尼亚淡水蟹 Aegla alacalufi 系统地理格局的影响。系统发育分析将东部大陆的冰川种群分为北群（7 个种群）和南群（1 个种群），结果表明北群的系统发育结构较浅，而西部岛屿非冰川种群的系统发育结构较深，表明冰川对这些种群有显著影响。系统发育分析还确定了奇洛埃岛的 Yaldad 种群可能是一个未被识别的新物种。非冰川种群的种群间遗传分化高于冰川种群，但后者的种群遗传多样性没有降低。两个冰川种群分别于约 96800-29500 年前和约 104200-73800 年前与非冰川种群分化，它们似乎有不同的冰川避难所。出乎意料的是，非冰川岛屿并没有成为它们的避难所。冰川北群检测到种群扩张，末次冰盛期后种群呈持续增长。嵌套分支分析表明，可能存在从西部岛屿到东部大陆的殖民化。到达大陆并在那里度过末次冰期后，种群可能会从高海拔到低海拔扩张，随着融冰洪水的到来。Aegla alacalufi 的遗传多样性主要受到更新世冰川的影响，最小程度上受到水系隔离的影响。
