IF THE SHREW FITS, SEQUENCE IT: THE HISTORICAL BIOGEOGRAPHY OF EURASIAN SHREWS

Abstract

Eurasia\u27s ancient geology and extreme environments, combined with diverse topography and Quaternary climate oscillations, have significantly influenced the genetic structure of its fauna. Unlike Europe and North America, much of high latitude Asia remained ice-free during glaciation, allowing species to persist more widely. However, this region has received limited research attention. In my study, I examined shrews in the Sorex ‘caecutiens’ and ‘minutus’ groups to understand genetic relationships across Eurasia. Using mitochondrial cytochrome b gene data, I identified well-supported phylogenetic relationships and found that Pacific Coastal Archipelagos played a key role in shrew diversification. Additionally, a longitudinal gradient of genetic diversity was observed, reflecting east-west population expansions during the Late Pleistocene. This contrasts with the northward expansion seen in European and North American species. My findings provide new insights into the historical biogeography of a minimally studied region of Asia