Distribution and phylogenetic relationships of the Mexican large-toothed shrew Sorex macrodon

Abstract The large-toothed shrew, Sorex macrodon , is distributed in the cloud forests of the southern Sierra Madre Oriental, the eastern Trans-Mexican Volcanic Belt, and the northeastern Sierra Madre del Sur. This study tested the hypothesis that the canyons of the Blanco, Santo Domingo, and Cajonos Rivers constitute geographical barriers that promote interpopulation differentiation in S. macrodon . We integrated ecological niche modeling, phylogenetic analyses, and morphometrics to assess potential intra-specific differentiation in response to climatic and topographic variations across its geographic range. The potential distribution map suggests that the Santo Domingo River canyon is unsuitable for S. macrodon . Phylogenetic analyses revealed two monophyletic groups within the species, with distinct haplotypes north and south of this canyon, and a p-distance of 3.16% between populations. However, morphometric analyses showed few significant differences between genetic groups. The Santo Domingo River canyon appears to promote differentiation and limit distribution in S. macrodon and in other vertebrate groups associated with cloud forests, and the ecosystem distribution itself. The discordance between genetic and morphometric data may result from recent intra-specific divergence (0.71 Ma), as suggested by divergence time analysis. To understand population dynamics and differentiation-promoting processes in this species, evaluating its historical distribution, including additional specimens, is necessary.