Accelerated molecular evolution in Microtus (Rodentia) as assessed via complete mitochondrial genome sequences

Microtus is one of the most taxonomically diverse mammalian genera, including over 60 extant species. These rodents have evolved rapidly, as the genus originated less than 2 million years ago. If these numbers are taken at face value, then an average of 30 microtine speciation events have occurred e...

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Bibliographic Details
Published in:Genetica 2006-09, Vol.128 (1-3), p.95-108
Main Authors: Triant, Deborah A, Dewoody, J Andrew
Format: Article
Language:English
Subjects:
Animals
Arvicolinae - classification
Arvicolinae - genetics
Base Sequence
Cytochrome b
Cytochromes b - genetics
DNA Primers - genetics
DNA, Mitochondrial - genetics
Evolution
Evolution, Molecular
Genome
Mammals
Microtus
Mitochondrial DNA
Molecular Sequence Data
Phenotypic variations
Rodentia
Rodents
Sequence Alignment
Speciation
Species Specificity
Time Factors
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Summary:Microtus is one of the most taxonomically diverse mammalian genera, including over 60 extant species. These rodents have evolved rapidly, as the genus originated less than 2 million years ago. If these numbers are taken at face value, then an average of 30 microtine speciation events have occurred every million years. One explanation for the rapid rate of cladogenesis in Microtus could be the karyotypic differentiation exhibited across the genus: diploid numbers range from 17 to 64. Despite the striking chromosomal variability within Microtus, phenotypic variation is unremarkable. To determine whether nucleotide substitution rates are also elevated in voles, we sequenced the entire mitochondrial DNA (mtDNA) genome of the Eurasian sibling vole (Microtus rossiaemeridionalis). We compared this genome to another previously sequenced vole mtDNA genome (Microtus kikuchii) and performed pairwise sequence comparisons with the mtDNA genomes of ten additional mammalian genera. We found that microtine mtDNA genomes are evolving more rapidly than any other mammalian lineage we sampled, as gauged by the rate of nucleotide substitution across the entire mtDNA genome as well as at each individual protein-coding gene. Additionally, we compared substitution rates within the cytochrome b gene to seven other rodent genera and found that Microtus mtDNA is evolving fastest. The root cause of accelerated evolution in Microtus remains uncertain, but merits further investigation.
ISSN:0016-6707
1573-6857
DOI:10.1007/s10709-005-5538-6