Influence of interspecific competitors on behavioral thermoregulation: developmental or acute plasticity?

Many ectotherms reduce their exposure to changing thermal conditions using behavioral thermoregulation. The effectiveness of behavioral thermoregulation in maintaining ectotherm body temperatures within the target range is influenced not only by environmental (operative) temperatures but also by the presence of other con- and heterospecific individuals. How species’ interactions affect behavioral thermoregulation is largely unknown. Theory predicts that species’ interactions could affect the plasticity of behavioral thermoregulation in two ways, i.e. by developmental plasticity of a preferred temperature range or by an acute shift in body temperatures. Empirical tests of these predictions are scarce. We examined the developmental and acute effects of heterospecific social interactions on the accuracy and effectiveness of thermoregulation in larvae of two competing species, Ichthyosaura alpestris and Lissotriton vulgaris. The presence of heterospecifics during larval development had no e...