Molecular phylogeny and evolution of the Asian lineage of vole genus Microtus (Rodentia: Arvicolinae) inferred from mitochondrial cytochrome b sequence
Abstract: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. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 595–613.
Document Type: Research Article
Affiliations: 1: Lomonosov Moscow State University, Vorobievy Gory, 119992, Russia 2: Zoological Museum of Moscow State University, B. Nikitskaya 6, 125009, Russia 3: Engelhardt Institute of Molecular Biology, RAS, Moscow 119991, Russia 4: Zoological Institute RAS, Universitetskaya nab. 1, 199034, St.Petersburg, Russia 5: Geological Institute RAS, Pyzhevsky 7, 119017 Moscow, Russia
Publication date: March 1, 2010