SEX-RELATED SPATIAL KIN STRUCTURE IN A SPRING POPULATION OF GREY-SIDED VOLES CLETHRIONOMYS RUFOCANUS AS REVEALED BY MITOCHONDRIAL AND MICROSATELLITE DNA ANALYSES

Polymerase chain reaction-directed mitochondria (mt) and microsatellit e DNA analyses were performed to examine the kin structure in a spring population of grey-sided voles Clethrionomys rufocanus in Hokkaido, J apan. The spatial distribution of 81 voles in a trapping grid (about 1 ha) was estimated by using the catch-mark-release method. DNA samples were extracted from the toes clipped for individual identification. M aternal lineages of voles were unequivocally determined by the mtDNA h aplotypes, as identified by nucleotide sequencing of the control regio n. Relatedness between individuals was estimated based on the genotype and allele frequencies at several microsatellite loci. Although the d istribution of voles was uniform within the grid, neighbouring females were frequently from the same maternal lineage. Relatedness values be tween females correlated negatively with geographical distances. Combi nation of the two molecular markers revealed four clusters of closely related, matrilineal females in the population, whereas no such cluste r was apparent in males. The present study first demonstrated a sex-re lated spatial kin structure in a natural population of the grey-sided vole.