2025/04/13 by Antonia Androski, Jason L. Malaney, John R. Demboski +3 · 2 voices
Environmental Science · Biochemistry, Genetics and Molecular Biology · #Species Distribution and Climate Change #Genetic diversity and population structure #Animal Ecology and Behavior Studies
paper · doi:10.1093/jmammal/gyaf019
openalex publication_date 2025/04/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/23
Abstract The Montane Shrew, Sorex monticola, is a common and wide-ranging mammal throughout western North America. Previous studies identified multiple mitochondrial lineages, but limited geographic sampling constrained our understanding of distributional limits, phylogeographic variation, and biogeographic history. We used range-wide sampling and multi-model phylogenetic analyses to examine mitochondrial phylogeographic variation, evaluate niche differentiation, and test historical biogeographic hypotheses. We examined cytochrome b gene sequences from 462 individuals and 277 localities across the distribution of S. monticola and related species, including the first specimens from the Sierra Nevada (California, United States) and Sierra Madre Occidental (Durango and Chihuahua, Mexico). Estimated genealogical relationships, divergence times, and delimitation approaches identified 3 well-supported, deeply divergent, geographically structured clades consistent with previous estimates (Coastal, Southern, Northern). Sorex monticola was paraphyletic with S. sonomae and all species of North American water shrews. We also identified minimal divergence between Coastal S. monticola and 2 nominal species, S. pacificus and S. bairdii, that are sympatric in the Pacific Northwest. Demographic tests indicated that some lineages represent stable and isolated island and montane populations, while others represent populations that experienced demographic expansion since the Last Glacial Maximum. Niche differentiation tests revealed that each clade occupies distinctive environmental conditions, with projections of future conditions suggesting that populations isolated in southern mountains may face extirpation associated with warming climate and aridification. This range-wide assessment of geographic genetic variation lays a foundation for selecting samples from key populations for expanded genome-level investigations into evolutionary relationships and taxonomic limits, enabling tests of hypotheses related to Pleistocene climatic drivers of biotic diversification processes across western North America.