Data from: Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania

Background: The aim of this research was to identify the effects of Pleistocene climate change on the distribution of fauna in Tasmania, and contrast this with biotic responses in other temperate regions in the Northern and Southern Hemisphere that experienced glacial activity during this epoch. This was achieved by examining the phylogeographic patterns in a widely distributed Tasmanian endemic reptile, Niveoscincus ocellatus. 204 individuals from 29 populations across the distributional range of N. ocellatus were surveyed for variation at two mitochondrial genes (ND2, ND4), and two nuclear genes (β-globin, RPS8). Phylogenetic relationships were reconstructed using a range of methods (maximum parsimony, Bayesian inference and haplotype networks) and the demographic histories of populations were assessed (AMOVA, Tajima’s D, Fu’s Fs, mismatch distributions, extended Bayesian skyline plots, and relaxed random walk analyses). Results: There was a high degree of mitochondrial haplotype diversity (96 unique haplotypes) and phylogeographic structure, where spatially distinct groups were associated with Tasmania’s Northeast and a large area covering Southeast and Central Tasmania. Phylogeographic structure was also present within each major group, but the degree varied regionally, being highest in the Northeast. Only the Southeastern group had a signature of demographic expansion, occurring during the Pleistocene but post-dating the Last Glacial Maximum. In contrast, nuclear DNA had low levels of variation and a lack of phylogeographic structure, and further loci should be surveyed to corroborate the mitochondrial inferences.Conclusions: The phylogeographic patterns of N. ocellatus indicate recent range and demographic expansion in N. ocellatus, particularly in the Southeast and Central areas of Tasmania. Expansion in Central and Southeastern areas appears to have been more recent in both demographic and spatial contexts, than in Northeast Tasmania, which is consistent with inferences for other taxa of greater stability and persistence in Northeast Tasmania during the Last Glacial Maximum. These phylogeographic patterns indicate contrasting demographic histories of populations in close proximity to areas directly affected by glaciers in the Southern Hemisphere during the LGM.背景：本研究旨在明确更新世（Pleistocene）气候变化对塔斯马尼亚动物区系分布的影响，并将其与南北半球其他在该时期经历冰川活动的温带区域的生物响应进行对比。本研究以广泛分布的塔斯马尼亚特有爬行动物眼斑石龙（Niveoscincus ocellatus）为研究对象，对其系统地理学格局展开分析。研究共采集该物种分布范围内29个种群的204个个体，对2个线粒体基因（mitochondrial genes）ND2、ND4以及2个核基因（nuclear genes）β-珠蛋白、RPS8的变异情况进行了检测。系统发育关系通过多种方法重建，包括最大简约法（maximum parsimony）、贝叶斯推断（Bayesian inference）及单倍型网络（haplotype networks）；同时对种群的历史动态开展评估，涵盖分子方差分析（Analysis of Molecular Variance, AMOVA）、塔伊马D检验（Tajima’s D）、傅氏Fs检验（Fu’s Fs）、错配分布（mismatch distributions）、扩展贝叶斯天际线图（extended Bayesian skyline plots）以及松弛随机游走分析（relaxed random walk analyses）。结果：本研究检测到较高的线粒体单倍型多样性，共获得96个独特单倍型，且存在显著的系统地理学结构：空间上分化的类群分别对应塔斯马尼亚东北部区域，以及覆盖东南部与中部的大片区域。两个主要类群内部均存在系统地理学结构，但区域间的分化程度存在差异，东北部类群的分化程度最高。仅东南部类群呈现出种群扩张的信号，该扩张发生于更新世时期，但晚于末次盛冰期（Last Glacial Maximum, LGM）。与之形成对比的是，核基因的变异水平较低且无明显系统地理学结构，因此需进一步检测更多基因座以验证线粒体基因的分析结果。结论：眼斑石龙的系统地理学格局表明，该物种近期发生了分布范围与种群扩张，尤其在塔斯马尼亚东南部与中部区域。相较于塔斯马尼亚东北部类群，中部与东南部类群的种群扩张在种群动态与空间分布层面均发生得更晚，这与其他类群的相关推论一致——即塔斯马尼亚东北部区域在末次盛冰期（LGM）期间具有更高的种群稳定性与存续性。上述系统地理学格局显示，在末次盛冰期受冰川直接影响的邻近区域内，南半球不同种群的种群历史动态存在显著差异。