Giarla Thomas C, Jansa Sharon A
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA; J.F. Bell Museum of Natural History, University of Minnesota, St. Paul, MN, 55108, USA.
Mol Ecol. 2015 May;24(10):2495-506. doi: 10.1111/mec.13173. Epub 2015 Apr 22.
Climate oscillations during the Quaternary altered the distributions of terrestrial animals at a global scale. In mountainous regions, temperature fluctuations may have led to shifts in range size and population size as species tracked their shifting habitats upslope or downslope. This creates the potential for both allopatric speciation and population size fluctuations, as species are either constrained to smaller patches of habitat at higher elevations or able to expand into broader areas at higher latitudes. We considered the impact of climate oscillations on three pairs of marsupial species from the Andes (Thylamys opossums) by inferring divergence times and demographic changes. We compare four different divergence dating approaches, using anywhere from one to 26 loci. Each pair comprises a northern (tropical) lineage and a southern (subtropical to temperate) lineage. We predicted that divergences would have occurred during the last interglacial (LIG) period approximately 125 000 years ago and that population sizes for northern and southern lineages would either contract or expand, respectively. Our results suggest that all three north-south pairs diverged in the late Pleistocene during or slightly after the LIG. The three northern lineages showed no signs of population expansion, whereas two southern lineages exhibited dramatic, recent expansions. We attribute the difference in responses between tropical and subtropical lineages to the availability of 'montane-like' habitats at lower elevations in regions at higher latitudes. We conclude that climate oscillations of the late Quaternary had a powerful impact on the evolutionary history of some of these species, both promoting speciation and leading to significant population size shifts.
第四纪期间的气候振荡在全球范围内改变了陆地动物的分布。在山区，温度波动可能导致物种分布范围大小和种群大小发生变化，因为物种会随着栖息地的变化而上坡或下坡迁移。这就产生了异域物种形成和种群大小波动的可能性，因为物种要么被限制在高海拔地区较小的栖息地斑块中，要么能够在高纬度地区扩展到更广阔的区域。我们通过推断分化时间和种群动态变化，研究了气候振荡对来自安第斯山脉的三对有袋类物种（袋鼬属负鼠）的影响。我们比较了四种不同的分化时间测定方法，使用了1到26个基因座。每一对都包括一个北方（热带）谱系和一个南方（亚热带到温带）谱系。我们预测分化发生在大约12.5万年前的末次间冰期（LIG），并且北方和南方谱系的种群大小将分别收缩或扩张。我们的结果表明，所有三对南北谱系在末次间冰期期间或之后的晚更新世发生了分化。三个北方谱系没有种群扩张的迹象，而两个南方谱系则表现出近期的急剧扩张。我们将热带和亚热带谱系反应的差异归因于高纬度地区较低海拔处“类似山地”栖息地的可用性。我们得出结论，第四纪晚期的气候振荡对其中一些物种的进化历史产生了强大影响，既促进了物种形成，又导致了种群大小的显著变化。
