Biogeographical and ecological patterns of allometric trends in Ecuadorian whorltail-iguanas

Abstract. – For more than a century, studies have documented relationships between environmental variables and species morphology. Biogeographic and macroecological patterns have been identified across several faunal groups worldwide, revealing distinct trends for endotherms and ectotherms. We selected Stenocercus lizards as a model group to explore morphological variation in relation to geographic distribution and environmental variables in Neotropical ectotherms. We analysed intraspecific allometric variation and linear morphological data from 12 Stenocercus species from Ecuador across their elevational and latitudinal distributions. We also examined relationships between morphological variation and bioclimatic variables. We found that Stenocercus species at higher elevations have shorter limbs, whereas those at lower elevations have longer limbs. We did not find significant relationships between snout-vent length or head size and elevational or latitudinal distribution. Elevation and precipitation seasonality were the strongest explanatory variables. Finally, we discuss potential mechanisms underlying these biogeographic patterns and recommend further research that considers additional environmental variables at finer spatial scales.