Macroevolution of body size and sexual size dimorphism across lizards: distinct evolutionary patterns between the sexes

Males and females can exhibit differences in body size, producing sexual size dimorphism (SSD). Both body size and SSD vary markedly across taxa, providing a framework to examine whether male and female body sizes are coupled and to identify general versus lineage-specific patterns. Using evolutionary models, we compared rates and disparity patterns to evaluate whether male and female body size evolve in tandem and how SSD diverges across four speciose lizard families (Anolidae, Chamaeleonidae, Liolaemidae, and Phrynosomatidae) and a broader dataset encompassing 2476 Squamata species. Male body size evolved faster than female body size in all families except Liolaemidae, which exhibited the highest overall rates of evolution. Male and female body size displayed similar disparity patterns, contrasting with those of SSD. Our findings underscore the importance of analyzing male and female traits independently, as such analyses revealed differences in the trajectories of disparity in body size and SSD across taxa, and highlighted the distinct evolutionary dynamics of body size and dimorphism in the Andean Liolaemidae radiation. Overall, our study highlights the role of sex-specific evolution in shaping broader patterns of morphological diversity, offering insights into the macroevolutionary divergence of sexually dimorphic traits.