Cooperation behavior of fore- And hindlimbs during jumping in Rana dybowskii and Xenopus laevis

Abstract

Frogs are characterized by their outstanding jumping ability, depending on the rapid extension of hindlimbs to propel their bodies into air. A typical jumping cycle could be broken into four phases: preparation, takeoff, flight, and landing. Considerable research has been performed to discuss the function of hindlimbs of frogs during takeoff phase, whereas the literature of limbs' motion in jumping between different species was limited. To profile the evolution of locomotion in anurans, it is necessary to investigate on the motion of fore- and hindlimbs of frogs within different taxa. In this work, we put forward a detailed description of jumping behavior of two frog species, Rana dybowskii and Xenopus laevis. High-speed cameras were used to explore the movement of different joints in fore- and hindlimbs of these two animals, and kinematic analysis was operated to identify both homologous behaviors and significant differences between them. We found that the Rana dybowskii's fore- and hindlimbs had good cooperation during jumping, while the Xenopus laevis' uncooperative behavior in limbs may give a functional explanation for the deficiency in terrestrial jumping; besides, the R. dybowskii's landing followed the “hands-belly-feet slap” strategy, and Xenopus laevis had clumsy landing with “belly-flops” sequence. The result gained here clarifies the cooperation behavior of anuran limbs and may supply a new insight into our understanding of the anuran's evolution.