Population expansion, divergence, and persistence in western fence lizards (Sceloporus occidentalis) at the northern extreme of their distributional range

Population dynamics within species at the edge of their distributional range, including the formation of genetic structure during range expansion, are difficult to study when they have had limited time to evolve. Western Fence Lizards (Sceloporus occidentalis) have a patchy distribution at the northern edge of their range around the Puget Sound, Washington, where they almost exclusively occur on imperiled coastal habitats. The entire region was covered by Pleistocene glaciation as recently as 16,000 years ago, suggesting that populations must have colonized these habitats relatively recently. We tested for population differentiation across this landscape using genome-wide SNPs and morphological data. A time-calibrated species tree supports the hypothesis of a post-glacial establishment and subsequent population expansion into the region. Despite a strong signal for fine-scale population genetic structure across the Puget Sound with as many as 8–10 distinct subpopulations supported by th...

物种分布范围边缘的种群动态——包括其扩张过程中遗传结构的形成——在演化时间有限时难以研究。西方栅栏蜥（Sceloporus occidentalis）在华盛顿州普吉特湾（Puget Sound）周边的分布范围北缘呈斑块状分布，且几乎仅栖息于濒危的沿海生境中。该区域在16000年前仍被更新世冰川（Pleistocene glaciation）覆盖，这表明这些种群定殖于该生境的时间相对较近。我们利用全基因组单核苷酸多态性（genome-wide SNPs）和形态学数据，检测了该区域内种群的分化情况。时间校准物种树（time-calibrated species tree）支持冰川期后定殖并随后向该区域扩张的假说。尽管普吉特湾区域存在强烈的精细尺度种群遗传结构信号，且多达8-10个不同的亚种群得到了...