Mitochondrial DNA restriction site variation in the Townsend's vole, Microtus townsendii

Abstract

The mitochondrial DNA (mtDNA) from the Townsend's vole, Microtus townsendii, was compared with mouse mtDNA by positioning vole restriction enzyme fragments on the known laboratory mouse mtDNA molecule by homology hybridization. The vole mitochondrial genome is conserved in general sequence organization and size but does contain a nonhomologous region of more than 600 base pairs not found in the mouse sequence. Thirty-five voles were collected from seven different localities throughout the range of the species, including insular populations on Bowen and Vancouver islands. The variation of vole mtDNA sequences within this species was assayed with six hexameric and four tetrameric type II restriction endonucleases. These individuals can be divided into seven distinct maternal lines. The level of nucleotide substitution between populations is shown to be as high as 0.896 ± 0.350%. The voles from Bowen Island showed no detectable variation within their population, or divergence from a mainland population on the adjacent coast. This fact suggests a recent colonization of Bowen Island. The samples from Vancouver Island fall into two major maternal lines, which show 0.453 ± 0.240% divergence. These insular maternal lines are 0.677 ± 0.257% divergent from the most closely related mainland population. These results suggest that the voles on Vancouver Island represent long-established maternal lines, and are not derived by a recent colonization from a mainland source population. Based on conservative estimates for rates of nucleotide substitution, Vancouver Island has been inhabited by the Townsend's vole since at least the Olympic interglacial.

Intra- and inter-specific mitochondrial DNA sequence divergence in Salmo: rainbow, steelhead, and cutthroat trouts

“…The levels of intraspecific nucleotide divergence displayed between rainbow trout and steelhead populations as measured by this technique are very similar to mtDNA sequence divergence determined for populations of Microtus townsendii (vole) collected from a comparable, although smaller geographic area of the Pacific northwest (Thomas 1984). These populations also showed divergence of less than 1%.…”

Macrogeographic variation in mitochondrial DNA of meadow voles (Microtus pennsylvanicus)

“…Our analysis reveals that M. pennsylvanicus and M. townsendii are well separated and that the meadow vole samples could be clustered into two major groups, the central and the eastern Canadian populations, with no apparent geographical ordering within the eastern group. The lack of concordance between phylogeny and local geography has been rarely observed in small mammals (but see Thomas and Beckenbach 1986), although it seems to be typical of the American eel (Anguilla rostrata) For personal use only. and humans (Brown 1980;Cann et al 1987).…”

Three patterns of mitochondrial DNA nucleotide divergence in the meadow vole, Microtus pennsylvanicus

“…It is noteworthy that Thomas and Beckenbach (1986) had a similar experience to ours when they used DNA hybridization to map mtDNA restriction fragments from another microtine, Microtus townsendii. In their investigation, a 700-bp Hind III fragment that mapped to the region of the ND5-ND6 genes failed to hybridize to any portion of the mouse mtDNA genome, and it was suggested that the 700-bp fragment might be nonhomologous to mouse mtDNA (Thomas and Beckenbach 1986).…”

“…In their investigation, a 700-bp Hind III fragment that mapped to the region of the ND5-ND6 genes failed to hybridize to any portion of the mouse mtDNA genome, and it was suggested that the 700-bp fragment might be nonhomologous to mouse mtDNA (Thomas and Beckenbach 1986). These observations seem to suggest that some regions of the microtine genome might be unusually divergent from that of mice.…”