Genomic Insights Into the Body Size Evolution in Mustelidae (Mammalia: Carnivora)

The extraordinary body size diversity within Mustelidae makes this carnivoran family an exceptional model for investigating adaptive evolution, yet the genomic underpinnings of their morphological variation have remained largely unexplored. Herein, we conducted a comprehensive comparative genomic analysis of 19 mustelid species to investigate the genetic foundations underlying the extraordinary range of body sizes within this family. We accounted for phylogenetic relatedness in our analyses to avoid statistical non-independence due to shared ancestry and identified 149 genes significantly associated with body mass variation across the mustelid phylogeny (body size-associated genes, BAGs) and, through selection pressure analyses, further detected 125 positively selected and 409 rapidly evolving genes in large-bodied mustelid lineages. We found that body size evolution in mustelids is driven by convergent positive selection in metabolic, developmental, and cytoskeletal pathways, with genes involved in growth signaling and energy metabolism underlying the remarkable morphological diversity observed across the family. Our study reveals the genetic basis of body size evolution in mustelids, offering important insights into the core mechanisms driving adaptive phenotypic diversity among mammals.