Population genetic structure of non-indigenous Callosciurus squirrels established in Hamamatsu City, Japan: Dominant haplotypes from Finlayson’s squirrels, revealed by a follow-up survey based on the mitochondrial D-loop region

Abstract

Non-indigenous Callosciurus squirrels have been introduced into Hamamatsu City of Shizuoka Prefecture, Japan in the 1980s, and since then, their distribution has been expanding from urban to suburban areas. Population genetic analyses based on the mitochondrial D-loop gene have revealed contamination of Finlayson’s squirrels Callosciurus finlaysonii in addition to the presence of Pallas’s squirrels Callosciurus erythraeus, but the past studies are confined to urban areas only. We thus re-examined the genotypic composition of 266 specimens widely exterminated from the city between June 2019 and January 2021. The analysis revealed that two haplotypes derived from Finlayson’s squirrels were dominant. No individuals with mitochondrial genes derived from Pallas’s squirrels was found, although the body color pattern of them matched with this squirrel species. The haplotype distribution in Hamamatsu City was independent of artificial structures such as highways and vegetation, suggesting that individual dispersal occurred widely.