Morphological and Molecular Recharacterization of the Rodent Genus Mus from Nepal Based on Museum Specimens

Abstract

The taxonomy and phylogeny of the subgenus Mus, the Eurasian lineage of the genus Mus, remain unresolved, even for the house mouse (Mus musculus). While the subgenus is diverse in Asia, few studies cover both its morphology and molecular phylogeny. We re-examined 70 specimens identified as M.cervicolor that were collected from central Nepal in 1968 and 1975 and are currently deposited in the Hokkaido University Natural History Museum. To compare morphological features, we examined skull geometric morphometrics and body coloration, and performed a phylogenetic analysis of the mitochondrial cytochrome b gene sequences of representative specimens. The specimens were most likely either M. booduga or M. musculus. The best morphological characteristics for distinguishing the two species were the nasal length ratio, which was high and low, respectively. Mus booduga was found to inhabit altitudes lower than 1000 m and have light ventral fur, while M. musculus inhabited various altitudes up to 3000 m and had variable fur color depending on the altitude. We also discuss the taxonomic status of the fawn-colored mouse M. cervicolor.

Phylogeographic study using nuclear genome sequences of <i>Asip</i> to infer the origins of ventral fur color variation in the house mouse <i>Mus musculus</i>

“…Mice from Nepal are known to harbor highly polymorphic CAS-related mtDNA haplotypes (Prager et al, 1998) and are known to be a distinct lineage (NEP) that differs from CAS, MUS, DOM and M. m. gentilulus from Yemen (Duplantier et al, 2002;Sakuma et al, 2016), indicating the presence of NEP haplotypes from around half a million years ago (Li et al, 2021). However, M. musculus from central Nepal (Kishimoto et al, 2021) is shown to have darkcolored ventral fur, with L* values ranging from 63 to 50, corresponding to the class of "light gray" and not "dark gray," suggesting that mice from central Nepal may not be responsible for the migration of dark gray fur that is now distributed in the southern part of Asia. Taking these observations together, it is possible to conclude that CAS mice expanded their range eastward with humans in prehistoric times from the vicinity of northern India.…”

Genealogical characterization of regional populations and dorsal coat color variation in the house mouse <i>Mus musculus</i> from Asia based on haplotype structure analysis of a gene-rich region harboring <i>Mc1r</i>

“…The house mouse (Mus musculus) shows considerable morphological variation among geographic populations, particularly in terms of coat color (e.g., Schwarz and Schwarz, 1943;Marshall, 1998;Lai et al, 2008;Kishimoto et al, 2021;Takeishi et al, 2021). It was once divided into > 10 subspecies based on morphological characteristics, including variation in dorsal and ventral coat color (Schwarz and Schwarz, 1943).…”