Morphological Variations in Toad-Headed Agama: Potential Responses to Diverse Microhabitats

The adaptive response of animals to microhabitat variations attracts much attention in evolutionary biology. Animal morphological traits exhibit close associations with microhabitat utilization, critically influencing organismal performance in specific habitats. However, how diverse desert microhabitats drive variations in morphology and related functions remains largely unclear. Here, with two populations of toad-headed agama (Phrynocephalus przewalskii) inhabiting semi-arid and arid areas, we compared the microhabitat characteristics as well as the variations in morphological characteristics and locomotor performances (running and burrowing) of lizards. Furthermore, by relating the functional differences and morphology, and thus the variation in microhabitats, we aimed to predict the adaptive morphological responses of toad-headed agama to a variation in microhabitats. We found the population from open microhabitats with solid substrates possessed longer forelimbs (brachium and antebrachium) and appendages (metacarpus, phalanges, front claw, and hind claw). They also presented higher sprint speeds and enhanced burrowing capabilities, particularly on a hard soil matrix. Therefore, the differences in morphology and function between the populations support the hypothesis that morphological characteristics are compatible with function and potentially indicate adaptive strategies within different microhabitats.