Quaternary Environmental Changes Shaped Mitochondrial DNA Diversity in the Large Japanese Wood Mouse Apodemus speciosus in Hokkaido, Japan

Abstract

Quaternary environmental change provided opportunities for rapid population expansion; however, the process of building the population spatial structures remains poorly understood. In this study, we determined the mitochondrial cytochrome b and control region sequences of 43 individuals of the large Japanese wood mouse (Apodemus speciosus) from Hokkaido, northern Japan and analyzed these data along with those from 40 other individuals. Consistent with the findings of our previous study, we found that two rapid expansion events, after the last glacial maximum (LGM) and Marine Isotope Stage (MIS) 4, shaped population genetic pattern of A. speciosus in Hokkaido. In northeastern Hokkaido, several ancient lineages that originated during MIS 3 were detected, whereas central Hokkaido was dominated by haplotypes descended from a single lineage that survived the LGM, suggesting that the populations of western part of Hokkaido were newly formed by westward migration from eastern Hokkaido during the post-LGM warm period. Alternatively, as post-LGM vegetation recovery is thought to have occurred gradually from west to east in Hokkaido, population expansion started in the west and moved gradually to the east, resulting in eastward haplotype movement; thus, western and eastern Hokkaido may have served as the haplotype source and sink, respectively.

Ice age land bridges to continental islands: Repeated migration of the forest‐dwelling sable in northeastern Asia

“…This may be a result of past forest fragmentation within the island during glacial periods (Igarashi, 2016), which would have forced the sable to retreat into micro‐refugia and promoted genetic diversification within the island. Similar patterns have been suggested for other terrestrial mammals in Hokkaido (Inoue et al., 2022; Kawai et al., 2013; Kinoshita et al., 2012; Noda et al., 2016; Suzuki et al., 2015). Alternatively, the outcome could be a result of severe hunting pressure prior to prohibition in 1920 (Hirakawa et al., 2015).…”

“…for other terrestrial mammals in Hokkaido (Inoue et al, 2022;Kawai et al, 2013;Kinoshita et al, 2012;Noda et al, 2016;Suzuki et al, 2015). Alternatively, the outcome could be a result of severe hunting pressure prior to prohibition in 1920 (Hirakawa et al, 2015).…”

Editorial

“…The authors of award-winning papers are given a certificate and the right for their paper to be OA for free. I would like to congratulate the two winning papers from 2022, both of which are available as OA: Murakami et al (2022) and Inoue et al (2022). The following explanations were published by the Mammal Study Award Committee, providing their rationale for the winning selections (Chair: Hayato Iijima):…”

“…Inoue et al (2022): This study examined the effects of environmental changes during the Holocene on the population expansion of the large Japanese field mouse Apodemus speciosus from a genetic perspective. Using mitochondrial DNA sequences (cytochrome b and the control region) of samples from Hokkaido, Japan, obtained through a field survey and a database collection, the study examined the genetic differentiation among local populations and the timescale of the population expansion.…”