Effect of temperature, photoperiod, and feeding on the rate of tail regeneration in a semiaquatic plethodontid salamander

Abstract

Salamander tail autotomy improves survival, but loss of the tail can subsequently be costly. For example, burst swimming speed is significantly slower after autotomy in desmognathan salamanders, which may increase predation risk in aquatic habitats. However, any long-term cost of tail loss is contingent on the rate of tail regeneration. To examine variation among seasons and environments in the cost of tail autotomy, we tested the effect of temperature, photoperiod, and feeding on tail-length re-growth in the semiaquatic plethodontid salamander Desmognathus conanti. Eight experimental groups (n=15 each, equivalent in body size) were tested. After acclimation for four weeks at one of two temperatures (either 10°C or 20°C) and one of two photoperiods (either L:D 9.5:14.5h or 14.5:9.5h), 60% of the tail length was autotomized for each individual. After autotomy, each experimental group was maintained under unique conditions of temperature (either 10°C or 20°C), photoperiod (either L:D 9.5:14.5h or 14.5:9.5h), and feeding (either fasting or weekly feeding). The length of the regenerated tail portion for each individual was measured each week until the group with the fastest re-growth had regenerated 50% of the lost tail length. Low temperature had a large, negative effect, fasting had a small, negative effect, but photoperiod had no significant effect on tail re-growth. The large thermal effect resulted from a combination of delayed initiation of tail-length re-growth and reduced regeneration rate thereafter at low temperature. We conclude that the cost of salamander tail autotomy differs among seasons and environments based on variation in temperature and food availability.