Effect of body size on tail regeneration and recovery of swimming performance after caudal autotomy in a plethodontid salamander

I examined the effect of body size on the locomotor cost of caudal autotomy in the plethodontid salamander Desmognathus quadramaculatus. In this primarily aquatic species, larger individuals autotomize the tail less readily than smaller individuals, and this may be related to a greater locomotor cost of tail loss for larger individuals. To determine whether the rate of regeneration for tail length and the recovery of maximal locomotor performance after caudal autotomy vary with body size, I measured the rate of tail re-growth and the swimming burst speed for 14 individuals (snout-vent length = 42-106 mm) as they regenerated their tails. Burst speeds of individuals were significantly reduced after caudal autotomy. With the loss of about 62% of tail length, mean burst speed declined about 50%. Thus, caudal autotomy was costly in terms of a reduction in maximal locomotor performance in an aquatic environment. After the regeneration of 50% of the tail length that was lost, post-autotomy swimming speeds were not significantly different from pre-autotomy swimming speeds. The time required for this amount of tail length regeneration (about 63-143 d) increased significantly with body size. The rate of re-growth for the lost tail length declined significantly after the regeneration of 50% of tail length. These results demonstrate that the locomotor cost of tail loss is greater for larger individuals of D. quadramaculatus, and this may be related to a lower propensity for caudal autotomy and a greater propensity for alternative antipredator mechanisms (e.g., biting) for such individuals.