For running or burying -- The toe fringe of Phrynocephalus mystaceus is important

Toe fringe is the most typical morphological feature of lizards adapted to sandy environments, and toe fringe is suitable for testing the adaptive convergence suggested by form-environment correlations. Phrynocephalus mystaceus mainly lives in dune habitats, has a developed bilateral toe fringe, and exhibits fast sand-diving behavior for predator avoidance. We tested the effects of resecting the medial and bilateral toe fringes on the locomotor performance and sand-diving performance of P. mystaceus. The results showed that the individuals that had their medial toe fringe removed exhibited significantly faster sprint speeds than the unresected and all resected individuals (P <0.05). The results of stepwise regression analysis show that the relative area of the toe fringe is an important morphological feature that affects locomotor performance. The sand-burial performance scores of the unresected individuals were significantly greater than those of the resected individuals (P <0.05). The results of stepwise regression analysis show that the relative area of toe fringe and the axilla-groin length are the main morphological features that affect the sand-diving performance of P. mystaceus. After the bilateral toe fringe was removed, a significant negative correlation between locomotor and sand-diving performance was observed (P <0.05). Taken together, these results provide experimental evidence that toe fringe is positively associated with the locomotor and sand-diving performance of P. mystaceus.