Context-dependent body size evolution in lacertid lizards: differential role of structural habitat and climate across radiations.

Abstract

Body size plays a pivotal role in organismal performance, physiology, and ecology, making its evolution a key focus in biology. This study investigates the effects of structural habitat use (climbing vs. ground-dwelling) and climatic variables on body size evolution within the diverse Lacertidae lizard family and across phylogenetic scales. Our results reveal how structural habitat drives diversification rather than convergence toward specific morphological optima, with evolutionary rates varying substantially among phylogenetic groups. Gallotinae exhibits the highest evolutionary rates, likely due to island-driven dynamics, while Eremiadini and Lacertini display contrasting patterns linked to habitat use and evolutionary history. Similarly, climatic variables also influence body size variation by group. In Eremiadini, significant associations with temperature align with the heat conservation hypothesis. Lacertini body size negatively correlates with precipitation seasonality, supporting the seasonality hypothesis, while Gallotinae remains unaffected by climate, reflecting the unique pressures of insular evolution. This study highlights the importance of phylogenetic scale in understanding macroevolutionary patterns, revealing how broad-scale analyses may obscure context-specific eco-evolutionary dynamics. By focusing on coherent taxonomic groups, this research provides critical insights into how structural and climatic factors shape morphological diversity within Lacertidae.