Comparative chromosome and mitochondrial DNA analyses and phylogenetic relationships within common votes (Microtus, Arvicolidae)

The four species of common voles within the genus Microtus - M. kirgisorum, M. transcaspicus, M. arvalis, and M. rossiaemeridionalis - are so closely related that neither morphological features nor paleontological evidence al low clarification of their phylogeny. Analysis of vole karyotypes and mitoc hondrial DNA sequences, therefore, is essential for determining their phylo genetic relationships. A comparison of high resolution GTG-banding patterns allows us to ascertain the similarity between the karyotypes of these spec ies, revealing that they are composed of rearrangements of the same chromos omal elements. Based on this analysis, we propose possible routes of chromo somal divergence involved in speciation within this group of voles and cons truct a phylogenetic tree of their karyotypes, We suggest that two differen t karyotypic variants existed during the course of volve evolution one resu lting in M. rossiaemeridionalis and M. transcaspicus, the other, M. kirgiso rum and M. arvalis. As an alternative approach FITCH and KITSCH computer pr ograms were used to construct a phylogenetic tree of vole molecular evoluti on based on a pairwise comparison of mitochondrial cytochrome b sequences a nd the divergence time of the species was determined. The correlation betwe en the trees constructed using karyologic and molecular approaches is discu ssed in the context of other available data.