The effects of drift and selection on latitudinal genetic variation

Clinal variation is paramount for understanding the factors shaping genetic diversity in space and time. During the last glacial maximum, northern Europe was covered by glacial ice that rendered the region uninhabitable for most taxa. Different evolutionary processes during and after the recolonisation of this area from different glacial refugia have affected the genetic landscape of the present-day European flora and fauna. In this study, we focus on the common toad (Bufo bufo) in Sweden and present evidence suggesting that these processes have resulted in two separate lineages of common toad, which colonised Sweden from two directions. Using ddRAD sequencing data for demographic modelling, structure analyses and analyses of molecular variance (AMOVA), we provide evidence of a contact zone located between Uppland and Västerbotten in central Sweden. Genetic diversity was significantly higher in southern Sweden compared to the north, in accordance with a pattern of decreased genetic dive...

渐变群变异（clinal variation）是解析时空尺度下遗传多样性塑造机制的核心议题。末次冰盛期期间，北欧全境被冰川覆盖，致使绝大多数生物类群无法在此栖息繁衍。从不同冰期避难所出发完成该区域再定居的过程中及之后，各类演化进程共同塑造了现今欧洲动植物的遗传格局。本研究以瑞典境内的普通蟾蜍（Bufo bufo）为研究对象，结果表明上述演化进程催生了两支独立的普通蟾蜍谱系，二者分别从两个方向迁入瑞典。本研究利用双酶切简化基因组测序（ddRAD sequencing）数据开展种群历史动态建模、群体结构分析及分子方差分析（AMOVA），证实瑞典中部乌普兰省（Uppland）与西博滕省（Västerbotten）之间存在一处杂交接触带。瑞典南部的遗传多样性显著高于北部，这与遗传多样性随[原文此处截断]降低的分布模式相符。