Impact of climate changes from M iddle M iocene onwards on evolutionary diversification in E urasia: Insights from the mesobuthid scorpions

The aridification from M iddle M iocene onwards has transformed the A sian interior into an arid environment, and the P leistocene glacial–interglacial oscillations exerted further ecological impact. Therefore, both aridification and glaciation would have considerably influenced the evolution of many mid‐latitude species in temperate A sia. Here, we tested this perspective by a phylogeographic study of the mesobuthid scorpions across temperate A sia using one mitochondrial and three nuclear genes. Concordant mitochondrial and nuclear gene trees were obtained, which are consistent with species tree inferred using a B ayesian approach. The age of the most recent common ancestor ( MRCA ) of all the studied scorpions was estimated to be 12.49 Ma (late M iddle M iocene); M esobuthus eupeus diverged from the clade composing M esobuthus caucasicus and M esobuthus martensii in early L ate M iocene (10.21 Ma); M . martensii diverged from M . caucasicus at 5.53 Ma in L ate M iocene. The estimated MRCA ages of M . martensii and the Chinese lineage of M . eupeus were 2.37 and 0.68 Ma, respectively. C entral A sia was identified as the ancestral area for the lineage leading to M . martensii and M . caucasicus and the C hinese lineage of M . eupeus . The ancestral habitat of the genus M esobuthus is likely to have been characterized by an arid environment; a shift towards more humid habitat occurred in the MRCA of M . martensii and a lineage of M . caucasicus , finally leading to the adaptation of M . martensii to humid environment. Our data strongly support the idea that the stepwise intensified aridifications from M id‐ M iocene onwards drove the diversification of mesobuthid scorpions, and suggest that M . martensii and M . eupeus observed today in C hina originated from an ancestral lineage distributed in C entral A sia. Both the colonization and the ensuing evolution of these species in E ast A sia appear to have been further moulded by Q uaternary glaciations.