Meeting Abstract

74.1  Saturday, Jan. 5  The evolution of tail size, tail autotomy, and locomotor performance in lizards MCELROY, EJ*; BERGMANN, PJ; College of Charleston; Clark University mcelroye@cofc.edu

The effect of tail autotomy on locomotor performance has been studied in a number of lizard species. These studies show that tail autotomy can have a positive, a negative, or no effect on locomotor performance with a variety of mechanisms proposed to explain these findings. This study will test the hypothesis that tail size is correlated with the magnitude of change in performance after tail autotomy. To test this hypothesis, we compiled published records of the effect of tail autotomy on sprint speed in lizards. Based on these data, we measured relative tail length and volume using museum specimens. There is tremendous variation in relative tail size and the impact of autotomy on performance which inhibits the ability to detect patterns within the data. However, when the outlying species are down-weighted prior to regression analysis, we find a positive relationship between tail size and performance change after autotomy. Lizards with larger tails exhibit a larger change in performance after tail loss. Phylogenetically-informed analyses indicate that relative tail length and volume and the magnitude of change in sprint speed after autotomy have co-evolved. These findings suggest that future studies of tail autotomy and locomotor performance might be most productive if they focus on clades with large variation in tail size. To help identify such clades, we compiled all published records of relative tail length combined with a published lizard supertree, which yielded a final data set of 365 species. We then estimated the rate of relative tail length evolution for each lizard family. The results suggest uneven rates of tail length evolution across lizards, with several sister-families exhibiting very different rates (e.g. Pygopodidae – high rate, Gekkonidae, low rate).