Linking Ecological and Biogeographical Traits to Body Length and Dietary Breadth in Snakes.

Body size and dietary breadth are important for understanding animal evolution and adaptation. Snakes, as ecologically diverse predators with wide variation in morphology, reproduction, and diet, provide an excellent species group to explore how venom, reproductive mode, and biogeographical traits shape the evolution of ecological traits and dietary breadth. In this study, we compiled a global dataset of 4190 snake species and applied phylogenetically informed models to examine how traits such as venom, litter size, reproductive mode, and biogeographical characteristics across their geographic ranges (temperature, precipitation, and NDVI) influence body size and dietary breadth. We found that larger body size was consistently associated with greater dietary breadth, larger litter sizes, warmer climate, and higher vegetation. Dietary breadth, as an ecological outcome shaped by intrinsic functional traits, increased with venom, higher litter size, colder climate, and broader range size, though these effects varied across genera. Trait-function relationships were also influenced by ecological conditions: Body size increased more pronouncedly with both higher dietary breadth and vegetation in invertebrate-aquatic predators; the reduction in dietary breadth associated with warmer climates was more pronounced in open-canopy than forest-dwelling species. These findings show that ecological factors drive trait evolution in snakes by influencing body size and shaping dietary breadth. Our results could provide implications for snake conservation under global change by identifying trait combinations (e.g., small body size, narrow dietary breadth, limited range) that may increase vulnerability to climate-driven range shifts and help prioritize vulnerable lineages for conservation.