DOI: 10.5061/dryad.gmsbcc2sm
title: Preservation of genetic diversity in a highly fragmented population of the gray-sided vole Myodes rufocanus in an intensive farming region

description: Individual dispersal plays an important role in preserving genetic
 diversity in density-fluctuating populations of arvicoline rodents. When
 habitats are fragmented and dispersal between habitats is severely
 constrained, genetic diversity can be lost. Here, I investigated whether
 genetic diversity in the gray-sided vole Myodes rufocanus was preserved in
 an intensive farming region in Japan, where voles inhabited isolated
 windbreak forests along the borders of plowed lands. Genetic structure was
 examined in 673 vole samples (330 in spring and 343 in fall) collected at
 34 windbreak forests located 0.35–20 km apart. A part of the control
 region (425 bp) of mitochondrial DNA (mtDNA) was sequenced in 673 voles,
 yielding 76 haplotypes. Genetic differentiation of maternally inherited
 mtDNA among trapping sites was markedly lower in males than in females in
 both seasons, indicating strong male-biased dispersal. Genotypes at six
 microsatellite DNA loci were determined in 494 voles (245 in spring and
 249 in fall) from 18 trapping sites, and loci harbored 16–24 alleles. The
 mean number of alleles per locus (allelic diversity) at trapping sites was
 positively correlated with the number of examined individuals (density) in
 both seasons, and the relationship was very similar to that of a previous
 study performed in much less fragmented populations. Genetic
 differentiation of microsatellite DNA among trapping sites decreased
 considerably from spring to fall. In a STRUCTURE analysis with a most
 probable cluster number of two, closer trapping sites showed more similar
 mean values of cluster admixture proportions. The present findings
 indicate that gene flow among isolated windbreak forests, which occurred
 mainly by dispersal of males, was not restrained in this intensive farming
 region. Furthermore, the results suggest that genetic diversity in the
 study population was preserved as well as in less fragmented populations.
description: 1. Tissue samples were collected two times (spring and fall) in
 2007 at 34 trapping sites in Tokachi Plain in Hokkaido, Japan. During each
 trapping session, 30 Sherman-type traps were arranged in a 3 × 10 grid
 pattern at an interval of 10 m (~0.3 ha) for 2 nights (i.e., a total of 60
 trap-nights per session). Upon capture, three toes (one per foot) of each
 vole were clipped, sex was determined, and the vole was
 released. 2. Genomic DNA was extracted using the
 conventional phenol-chloroform method.  3-1. For mtDNA
 haplotype data, partial nucleotide sequences of the mtDNA control region
 were sequenced as described previously (de Guia et al., 2007). Here, the
 most variable part (425 bp) was sequenced using the internal primer HIP8
 (de Guia et al., 2007).                                
  de Guia, A. P., Saitoh, T., Ishibashi, Y., & Abe, H. (2007).
 Taxonomic status of the vole in Daikoku Island, Hokkaido, Japan:
 examination based on morphology and genetics. Mammal Study, 32(1), 33–44.
 doi:10.3106/1348-6160(2007)32[33:TSOTVI]2.0.CO;2 3-2.
 For microsatellite genotype data, six microsatellite loci (MSCRB-01, -04,
 -07, -09, -11, and -13) were genotyped as described previously (Ishibashi
 and Takahashi, 2021).    Ishibashi Y, Takahashi K.
 (2021) Role of individual dispersal in genetic resilience in fluctuating
 populations of the gray-sided vole <em>Myodes</em>
 <em>rufocanus</em>. Ecology and Evolution, 11(7), 3407–3421.
 doi:10.1002/ece3.7300.
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