Relationships among morphology, clinging performance and habitat use in Liolaemini lizards.

The central tenet of ecomorphological theory holds that different ecological requirements lead to different organismal designs (morphology). Here, we studied the relationships between performance (interlocking grasping) and forelimb morphological traits in species of lizards that exploit different structural habitats in a phylogenetic context. The performance (measured by the maximum force of clinging to substrate) was measured on different substrate types. After phylogenetically informed analyses, we found that arboreal and saxicolous species showed stronger resistance to mechanical traction in all substrates when compared to generalists and sand dweller lizards. These species showed a positive relationship between forelimb dimensions (humerus length and length of claw of toe 5) and maximum force exerted, on the contrary, hand width, claw height (CH) of digits III and IV and claw length of toe 4 showed a negative relationship. In addition, we observed a partial positive correlation between CH and maximal cling force on rough surfaces, but not on smooth surfaces.

The interplay between claw morphology and microhabitat use in neotropical iguanian lizards.

Traditionally, it has been suggested that variation in locomotor mode should be correlated with variation in the anatomy of the structures responsible for locomotion. Indeed, organisms can expand their ecological niche by using specialized traits of the locomotor system including hooks, claws, adhesive pads, etc. Despite the fact that claws are the most common biological mechanism of clinging in vertebrates, little is known about their function or evolutionary relationship to habitat use. The present study focuses on claw morphology in 57 species of iguanian lizards occupying different microhabitats. Qualitative differences in claw shape were explored by means of digital photographs, and quantitative measurements of the length, height and curvature of the claws of both fingers and toes were taken and correlated to information on microhabitat use obtained from the literature. Our analyses showed a strong phylogenetic component that obscured relationships between morphology and ecology. Our results also show differences in claw morphology between species that appear to be related to microhabitat use (climbing versus terrestrial species), with the best ecological descriptors being claw length and height. Performance measures and biomechanical analyses of claw function may consequently be better suited to explain the evolution of claw shape in relation to habitat use in this group.