Meeting Abstract

98.3  Wednesday, Jan. 7  Adaptations of the perivertebral musculature to different locomotor behaviours in lizards. MORITZ, S.; Friedrich-Schiller-Universitaet Jena sabine.moritz@uni-jena.de

Although the trunk and its associated musculature play an important role during locomotion in lizards, studies on the locomotor apparatus are biased towards legs and only very few studies on the axial musculature exist. One feature determining muscular properties is the fibre type composition. Generally, oxidative muscles contract slow but are fatigue-resistant, while glycolytic muscles contract fast but fatigue quickly. Locomotor behaviour in lizard species ranges from slow exploratory walking, fast prey-ambushing or escape behaviours (burst locomotion) to pursuit hunting over longer distances. In order to investigate how the musculature meets the demands of these different locomotor strategies, the three-dimensional fibre type distribution of the perivertebral muscles in three distantly related lizard species (Varanus exanthematicus, Dipsosaurus dorsalis, Acanthodactylus maculatus) was studied using enzyme-histochemistry on frozen serial sections. Despite the highly comparable axial movements among the species, the fibre type distribution differed strikingly. The results are consistent with their different locomotor strategies. While the axial muscles were highly oxidative in the pursuit hunter Varanus, they were highly glycolytic in the ambush hunter Dipsosaurus. Thus, the metabolic profile reflects the functional trade-off between respiration (e.g. oxygen availability) and locomotion. Species that can not ventilate while running show a highly glycolytic profile and exhibit burst locomotion, whereas Varanus with its accessory gular pump and thus slower oxygen depletion is capable of sustained locomotion and shows highly oxidative muscles.