Biological and environmental drivers of Liolaemus species distribution: A case story East of the Andes

Abstract

Understanding what determines species distribution is a central goal in biogeography and macroecology, particularly in the context of ongoing environmental change. In this study we explored how intrinsic (biological) and extrinsic (environmental) factors influence the distribution of Liolaemus lizards occurring east of the Andes, and evaluated the extent to which their distribution patterns support Rapoport’s rule. We analyzed 38 species, spanning Argentina from 52◦S to 23◦S, covering about 50 % of the genus distribution from sea level to 4300 masl. We used two main approaches, polygons and ecological niche models (ENMs), to evaluate the role of intrinsic factors such as critical thermal minimum (CTmin), thermal tolerance range, body size, and diet; and extrinsic factors including temperature, precipitation, elevation, and vegetation index. Our results show that CTmin is a strong predictor of range size under the ENMs approach, suggesting that greater cold tolerance is associated with broader distributions. Under the polygon approach, broader ranges correlated with colder, drier climates with pronounced seasonality. Although diet showed a weak tendency for narrower ranges in herbivorous species, it was a poor predictor overall. Thermal tolerance range, expected to increase with latitude under the climatic variability hypothesis, did not show a significant association with range size, and thus Rapoport’s rule was not supported. Furthermore, taxonomic uncertainties may obscure biogeographic patterns, particularly in widely distributed species that might represent species complexes not yet formally described. These findings highlight the combined role of biological and environmental factors, challenge the general applicability of Rapoport’s rule in Liolaemus, and underscore cold tolerance as a key distribution driver.