Geographic variation of Mus caroli from East and Southeast Asia based on mitochondrial cytochrome b gene sequences

Abstract

We examined intraspecific genetic variation in the mitochondrial cytochrome b gene (1140 bp) in the Okinawa mouse, Mus caroli (Rodentia, Muridae), from Okinawa, Taiwan, Hainan, Yunnan (southern China), Thailand, Vietnam and Java, to better understand their evolutionary history and human impact on dispersal and colonization by the mice. Populations from each of the seven localities had distinctive mitochondrial DNA sequences. The genetic distances, ranging from 0.015 to 0.045 (0.033 on average), were comparable with inter-subspecies differences in the house mouse Mus musculus (0.024). Assuming that nucleotide substitutions occur at a constant rate of 0.024/million years/lineage for mitochondrial DNA, the divergence of in M. caroli is estimated to have occurred 0.3-0.9 million years ago. The relatively great extent of intraspecific mitochondrial DNA variation in this taxon, and the spatial mode of variation suggest that M. caroli is genetically structured in space, to a considerable extent. Our data imply that local insular populations of M. caroli have been separated for long evolutionary periods, and that the scattered distribution patterns in the insular domains are due to historical shrinkage of appropriate areas of habitat, rather than to recent establishment of dispersed local populations by inadvertent human introductions.

Comparative analysis of evolutionary modes in Mc1r coat color gene in wild mice and mustelids

“…Mus caroli and M. terricolor are both closely associated with open grassland or swampy habitat (including rice fields) and they show remarkably little variation in coat color across wide geographic ranges. In the case of M. caroli, this uniformity in external appearance contrasts with mtDNA evidence for considerable phylogeographic substructuring (Terashima et al, 2003;Shimada et al, 2007b). We postulate that the Mc1r gene in both of these taxa may be under even stronger functional constraint than other members of the group, due perhaps to their preferred, essentially open habitat.…”

Morphological Variation of the House Mouse Mus musculus and the Ryukyu Mouse M. caroli (Mammalia: Muridae) from Japan

“…Within Japan, M. caroli is distributed only on Okinawajima Island, where M. caroli and M. musculus are sympatric (Motokawa 1995, 2000; Motokawa et al 2003; Motokawa 2007; Iwasa 2015). Although it has been suggested that M. caroli on Okinawajima Island was introduced by humans (Motokawa 2000; Motokawa et al 2003), the population of M. caroli on Okinawajima Island exhibits genetic and morphological diversification from other populations of M. caroli (Motokawa et al 2003; Terashima et al 2003), suggesting that M. caroli in Okinawajima Island was established naturally, not by the human introduction (Terashima et al 2003). Shimada et al (2007), on the other hand, showed that Okinawajima Island population was closely related to the Laos lineage and supposed the Okinawajima Island population to have been introduced by humans.…”