Climatic niche divergence in the diversification of long-haired mice of the subgenus Abrothrix (Cricetidae: Abrotrichini)

Abstract Advances in methods integrating phylogenetic information into climatic niche characterization have enabled a more explicit assessment of ecological factors in lineage diversification. Using these approaches, the climatic niches of long-haired mice of the subgenus Abrothrix were analyzed to reconstruct their evolutionary trajectories and evaluate whether variation in climatic dimensions reflects phylogenetic relatedness. Results show pervasive differentiation of realized climatic niches across all lineages and statistically significant divergence of fundamental niches in all sister-species pairs. Although climatic variation across species’ ranges was best described by a Brownian motion model, no significant phylogenetic signal was detected, indicating a decoupling between climatic niche evolution and phylogenetic relatedness. Patterns of niche overlap further revealed that levels of overlap are higher when climatic dimensions are evaluated individually than when considered jointly in multidimensional space. Reconstructions of niche evolution suggest that early diversification within subgenus Abrothrix was driven primarily by geographic isolation, consistent with low climatic differentiation among ancestral lineages. In contrast, subsequent divergences leading to extant species were associated with increased climatic niche differentiation, likely promoted by adaptive responses to environmental changes in southern South America. Together, these findings highlight the role of divergent selection in shaping climatic niche evolution among Abrothrix mice and suggest that environmental heterogeneity played a central role in the diversification of this clade. More broadly, this study provides an ecological perspective on speciation processes and supports the hypothesis that diversification in some Sigmodontinae rodents may have been related to adaptive changes linked to climatic variation.