Phylogeography of the common toad (Bufo bufo, Lissamphibia: Anura) in Switzerland

While Bufo bufo is widespread in Europe, the closely related B. spinosus is parapatrically distributed in Western Europe and Northern Africa. The exact course of the contact zone between both taxa, however, is still unknown. 24 samples from Switzerland were analysed using mitochondrial and nuclear markers combined with 243 previously published samples from Europe and Asia. No haplotypes of B. spinosus were detected in Switzerland, only two mitochondrial haplotypes of B. bufo: one north and south of the Alps, the other only north of the Alps. Both haplotypes are also widely distributed in Eastern and Central Europe. These results agree with a postglacial recolonisation of Central Europe from refugia on the Balkan Peninsula. The occurrence of one haplotype north and south of the Alps can be explained by colonisation either from the north by crossing the Alps or from the east along the southern edge of the Alps. The rapid postglacial recolonisation from Balkan refugia might have prevented the spread of southern haplotypes from Italy and of B. spinosus from France.

尽管青蛙属的 Bufo bufo 在欧洲广泛分布，其密切相关的近缘种 B. spinosus 则在西北欧及北非地区呈狭域分布。然而，两者之间的接触带的确切走向仍属未知。通过对瑞士采集的24个样本进行线粒体和核标记分析，并结合先前发表的来自欧洲和亚洲的243个样本，研究人员并未在瑞士发现 B. spinosus 的任何单倍型，仅检测到两种 Bufo bufo 的线粒体单倍型：一种位于阿尔卑斯山脉南北两侧，另一种仅位于山脉北侧。这两种单倍型在东欧和中欧也广泛分布。这些结果与来自巴尔干半岛的庇护所对中欧的冰川后期再殖民过程相吻合。阿尔卑斯山脉南北两侧出现的单倍型可能是由北部的迁徙穿越阿尔卑斯山脉，或沿阿尔卑斯山脉南缘从东部迁徙而来。从巴尔干半岛庇护所的快速冰川后期再殖民可能阻止了来自意大利的南方单倍型以及来自法国的 B. spinosus 单倍型的扩散。