Meeting Abstract
How an animal moves, and the energy required for that movement, has a profound effect on the evolutionary success of a given species. This study aimed to determine the evolution of cost of transport, the energy required to move a kilogram one meter, across amniotes. This study used comparative phylogenetic methods to demonstrate the complex evolutionary pattern of cost of transport among amniotes. I compiled previously published data on the net metabolic cost of both walking and running separately after subtracting the resting or standing cost. I then used phylogenetic adjusted statistics and Ornstein-Uhlenbeck modeling to determine substantial rate shifts along branches of the phylogenetic tree. Non-paleognathous birds have undergone a large increase in cost of transport, which suggests that the evolution of flight prevents terrestrial locomotion from being at its adaptive optimum. Domesticated camels and donkeys have undergone a substantial decrease in cost of transport from their closest living relatives. Previous research has suggested that their exceptionally low cost of transport is an adapative response to harsh environments. The results of this study are in line with this hypothesis, although further research is needed to determine whether it is a result of artificial selection, environment, or both. Turtles have a very low cost of transport, but the magnitude of the shift of cost of transport cannot be determined at this time due to the 230–million–year divergence from archosaurs and sparse sampling. Wallabies are the only taxon that have undergone directional selection on the cost of transport for running, resulting in an exceptionally efficient gait. It is possible that the lack of selection in other lineages may indicate that there is relaxed selection on cost of transport in running in comparison to walking.
