Phylogenetic and adaptive evolution of treeshrews (Scandentia)

Abstract Background Treeshrews (Scandentia) are a phylogenetically distinctive order of small mammals distributed in South and Southeast Asia and southwestern China. Their position within Euarchonta, heterogeneous histories of island and mainland diversification, and emerging genomic resources make them informative for studying mammalian evolution. Results This review systematically synthesizes the latest progress in the phylogeny, biogeography, genetic diversity, and molecular mechanisms underlying adaptive evolution in treeshrews. We provide a comprehensive overview of their evolutionary history spanning interordinal relationships, intraordinal diversification, and intraspecific differentiation, as well as the genetic basis of specialized sensory, immune, and metabolic traits. Conclusions Key priorities for future research include comprehensive taxon sampling, chromosome-level genome assemblies and population resequencing, integrative taxonomic revision, explicit testing of alternative biogeographic models, and experimental validation of candidate adaptive genes. Integrating genomic, morphological, ecological, and functional evidence will help resolve species boundaries, reconstruct the temporal and spatial history of Scandentia, and clarify the molecular basis of adaptive evolution.