To examine phylogenetic relationships within the Asian lineage of voles (Microtus) belonging to subgenus Alexandromys, the mitochondrial cytochrome b gene (cytb) was sequenced for its representatives, and the results were compared with the cytogenetic, morphological, and paleontological data. In all the trees inferred from maximum likelihood, parsimony, and Bayesian phylogenetic analyses, the Asian clade is subdivided into highly supported Alexandromys s.s. and moderately supported Pallasiinus lineages. Four subclades are recovered within Alexandromys: (1) Microtus maximowiczii and Microtus sachalinensis; (2) Microtus miiddendorffii s.l., Microtus mongolicus and Microtus gromovi; (3) Microtus fortis; and (4) Microtus limnophilus. Thus, M. limnophilus demonstrates clear affinities to Alexandromys s.s. but not to Microtus oeconomus (subgenus Pallasiinus), which was always regarded as its sibling species. The results obtained indicate M. mongolicus as a member of Alexandromys but not of the Microtus arvalis group, thus being concordant with the cytogenetic data. The mitochondrial data support the species status of M. gromovi; moreover, its placement as a part of a trichotomy with M. miiddendorffii s.l. and M. mongolicus contradicts the traditional affiliation of M. gromovi with M. maximowiczii. The divergence rate of cytb third position transversions in Microtus is estimated at approximately 8% per Myr, which corresponds to approximately 30% per Myr for all substitution types at all codon positions. The maximum likelihood distance based on complete sequence showed a tendency for a progressive underestimation of divergence and time for older splits. According to our molecular clock analysis employing nonlinear estimation methods, the split between Alexandromys and Pallasiinus and basal radiation within Alexandromys date back to approximately 1.2 Mya and 800 Kya, respectively.

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Geographic variation of 11 measurable cranial traits was studied on a set of 37 local samples of the Libyan jird, Meriones libycus, over its entire distribution area. MANOVA, cluster, canonical discriminant, and regression analyses were applied to consider both scalar and vector parameters of variation. It is shown that the Libyan jird is divided craniometrically into tree principal clusters, African, SWN Caspian, and main Asian ones, which differ basically by auditory bulla size (the least in SWN Caspian cluster) and incisive foramen length (the least in some subsamples of main Asian cluster). Auditory bulla size is shown to be negatively, though not very strongly, correlated with the aridity index. However, the SWN Caspian cluster is characterized by much smaller bulla than it is predicted by the regression with climatic parameter. This might be explained by some historical causes according to which a small size of auditory bulla in the jirds of that cluster reflects retention of the ancestral condition. It is suggested that subspecies M. l. caucasius from Azerbaijan is most conspicuously differentiated by cranial morphology, but its taxonomic relation to M. l. eversmanni from N Caspian region needs further clarification. The method of vector analysis of geographic trends within large portions of the areas of widely distributed species, such as M. libycus, seems to be useful in providing additional important information concerning biological specificity of respective territorial groupings.