Abstract
The objective of this study was to establish whether the Quaternary climatic fluctuations influenced the tempo and mode of diversification in Europeanrodents. Our case study is the subgenus Microtus (Terricola) distributed from western Europe to the Caucasus. Mitochondrial cytochrome b genesequences from several representatives of all the species were used to generate maximum-likelihood and Bayesian phylogenetic trees, to estimate divergencetimes, to identify biogeographic ancestral areas and to study the rate of diversification. Results showed that phylogenetic tree topologies weresimilar to previous published studies but with a better resolution at some nodes. The origin of Microtus (Terricola) is dated back to approximately4.05 Myr in the Early Pliocene, and molecular dating for most Terricola species corresponds to several glacial periods of the Pleistocene. Results ofthe biogeographic ancestral area reconstruction suggest that Microtus (Terricola) diversified from the Caucasus/Turkey/Iran area through western Europe.Several periods of diversity variation were highlighted as follows: two period of diversity increase, between 3 and 2 Myr, and after 1 Myr; twoperiods of diversity decrease, before 3 Myr, and between 2 and 1 Myr. The diversification rate of Microtus (Terricola) was 0.353 0.004 event/Myr,a rate similar to that of the Muridae family. To conclude, although the Pleistocene glacial conditions had an impact on the speciation events, theQuaternary does not appear however as a period with an exceptional rate of diversification for European rodents.