Insights Into Tribal-Level Adaptive Evolution and Phylogeny in Soricinae From Mitogenome of the Chinese Endemic Sorex...

Sorex cansulus is a Near Threatened shrew species endemic to China. To elucidate the adaptive evolution and evolutionary relationships of five tribes of the subfamily Soricinae, this study presented the morphology and complete mitogenome of S. cansulus. Codon usage bias analyses indicated that natural selection was the predominant force shaping its mitochondrial protein-coding genes, with the exception of the atp8 gene. We performed a comparative mitogenome analysis of 43 species across 13 genera and 5 tribes. The evolutionary rates (K _a/K _s) of 13 protein-coding genes across all tribes were significantly less than 1, implying strong purifying selection and evolutionary conservation. Notably, tribes with more similar K _a/K _s ratios exhibited closer evolutionary relationships. Phylogenetic trees yielded identical topologies and strongly supported the monophyly of Soricinae (PP = 1.00; BS = 100%). Both divergence time estimation and phylogenetic trees supported key taxonomic revisions: the reclassification of Episoriculus fumidus to the genus Pseudosoriculus; the elevation of Blarinella griselda to the genus Parablarinella, and the recognition of S. cansulus and Sorex sinalis as distinct sister species. However, some internal nodes within tribes showed relatively low nodal support, possibly due to incomplete taxon sampling or rapid radiative evolution. All five tribes retained the typical mammalian mitogenome organization, with the notable exception of Sorex daphaenodon, Sorex tundrensis, and Sorex araneus, which possessed an extra trnW gene (23 tRNA genes in total). These three species shared this unique feature and formed a distinct well-supported clade, the implications of which for their mitochondrial function and adaptation warrant further research.