Meeting Abstract

P3.133  Monday, Jan. 6 15:30  Measuring energetic costs of fossorial locomotion in lizards and snakes GERALD, GW; Nebraska Wesleyan University ggerald@nebrwesleyan.edu

Measuring the energetic costs of locomotion, termed “cost of transport,” is important when attempting to assess both intraspecific and interspecific variation in locomotor efficiency during both similar and disparate locomotor gaits. The traditional way of measuring costs of transport, which entails measuring gas exchange over time during a bout of locomotion, are not feasible for some modes of animal locomotion (due to, for example, an inability to assess consistent movements on a treadmill). However, measuring excess post-exercise consumption (EPOC) can be used to estimate energetic costs of movement during short bouts of activity and to facilitate comparisons among species and locomotor modes. In this study, EPOC was used to quantify fossorial locomotion in both lizards and snakes to empirically test the hypothesis that the limbless, tubular body type present in snakes and some lizards was selected for because limbs interfere with efficient fossorial movements. We predicted that lizards with relatively longer limbs would exhibit higher energetic costs during movement through narrow tunnels. We quantified EPOC after movements in different tunnel widths and found that the EPOC cost of transport (ECOT) increased with decreasing tunnel widths and with relatively larger limbs. This work supports the hypothesis that the increasing use of underground microhabitats by ancient lizards could have selected for limbless, tubular bodies over time that led to the evolution of present-day snakes and other limb-reduced lizards.