The Effect of Multiple Obstacles on the Locomotor Behavior and Performance of a Terrestrial Lizard, Sceloporus woodi

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The flexibility to negotiate variable terrain in three dimensionally complex environments is important for many terrestrial vertebrates. Variation in the substrate due to coarse woody debris, vegetation, rocks or a variety of other obstacles can alter escape paths and running performance. The ability to navigate obstacles is likely to directly influence survivorship via predator evasion, finding potential mates, and foraging. Earlier work has established that locomotor posture (quadrupedal, bipedal) and sprint performance are altered when organisms face an obstacle. In this study we focus on how multiple obstacles influence running behavior and locomotor posture in the Florida scrub lizard Sceloporus woodi. This species uses a variety of substrates (e.g. open sand, litter, and coarse woody debris) throughout its range. We hypothesize that an increasing number of obstacles will increase the frequency of bipedal running. We also hypothesize that using bipedal locomotion over multiple obstacles will allow a greater proportion of maximum sprint velocity to be maintained than quadrupedal running. Lizards were filmed running in a 2m long racetrack containing zero, one, two, or three obstacles. Velocity data will be explored by examining sprint sensitivities among the three trial types (one, two or three obstacles). Preliminary data show that the frequency of bipedal running is greater in lizards that encounter one or two obstacles, and lower for three obstacles. Trials in which bipedalism occurred were completed with fewer strides compared to quadrupedal runs. Overall this study will shed light on the locomotor behavior of lizards when interacting with obstacles in their environment. The broader implications of this research will be addressed as we attempt to provide further evidence in understanding why bipedalism occurs in so many lizard lineages.


Society for Integrative and Comparative Biology Annual Meeting (SICB)


Austin, TX