The influence of temperature on the defensive behaviour in Tomodon dorsatus (Serpente, Colubridae)

Abstract

Tetrapodes and ecotermicos vertebrates have a variable body temperature according to the temperature of the environment. Studies addressing lizards and snakes show that several behavior and functions of ectotermicos vertebrates suffer directly or indirectly influence of temperature on biological adequacy (fitness) (Bartholomew, 1982; Huey, 1982; Lillywhite,1987; Mori Burghardt, 2001). Anti-predatory behavior constitutes a special case among behaviors influenced by temperature, because it seems to suffer from various types of changes in different groups of tetrápodes ectotermicos as lizards, anuros amphibians, salamanders and snakes.These studies show that the temperature affects behavioral responses both in terms of magnitude and quality, which suggests that the changes on the type of behavior with temperature be consistent with the effects of temperature on the behavioral performance. From this point of view, colder animals, and therefore less fast animals, would prefer defensive responses based on aggression or in passivity, being the second case the one expected from species less capable of causing damage. This hypothesis is the focus of this work, and will be tested by an analysis on the behavior of the snake Tomodon dorsatus (Colubridae) at different temperatures, when exposed to an external stimulus simulating a predatory attack. This specie was chosen because it presents an enriched defensive repertoire (Bizerra, 1998). It is expected that animals with higher temperatures submit a higher locomotion and strike speed when compared with colder animals, and that aggressive or passive responses increase when reducing temperature. (AU)