Feeding kinematics of Phelsuma madagascariensis (Reptilia: Gekkonidae): testing differences between Iguania and Scleroglossa

摘要

The kinematics of feeding in the gekkotan lizard Phelsuma madagascariensis (Scleroglossa) was investigated using high-speed cinematography (200-300 frames s-1) and X-ray films (64 frames s-1). Qualitative kinematic analysis of the head and jaw displacement of the prey to (capture) and within (reduction, transport, swallowing, licking) the buccal cavity were compared for two types of prey (crickets [Gryllidae] and mealworms [Tenebrio molitor]) in 30 feeding sequences from four individuals. Maximal displacement of structures and timing of events were compared statistically to assess the differences among the phases and the prey using analysis of variance. P. madagascariensis uses its jaws only to capture the two types of prey item, and the capture jaw cycle is divided into fast-opening (FO), fast-closing (FC) and slow-closing (SC) stages only. As in iguanians and other scleroglossans, the reduction and transport cycles always involve a slow opening (SOI and SOII) stage before the FO stage, followedby FC and SC stages: this last stage was not easily identified in all feeding phase. Transport of the prey was followed by a large number of licking cycles. The data show (i) that the capture profile in gekkotans is similar to that observed for other scleroglossans and different from that described for iguanians (e.g. the absence of an SO stage); (ii) that the kinematics of jaw and related hyo-lingual cycles of intraoral manipulation (reduction and transport) are similar in lizards with a very different hyo-lingual system (Iguania, Gekkota and Scincomorpha), suggesting a basic mechanism of feeding cycles in squamates, transformed in varanids and snakes; and (iii) that prey type affects the kinematics of capture and manipulation, although the high level of variation among lizards suggests a possible individual modulation of feeding mechanism. A principal components analysis was performed to compare capture and transport cycles in this study of P. madagascariensis (Gekkota) and a previous study of Oplurus cuvieri (Iguania). This analysis separated the capture cycle of each species, but the transport cycles were not completely separated. These results demonstrate the complexity of the modulation and evolution of feeding process in squamates.