Testing the beneficial acclimation hypothesis: temperature effects on mating success in a butterfly

Traditionally, it has been assumed that all acclimation changes to the phenotype enhance the performance of an individual organism in the environment in which those changes were induced (beneficial acclimation hypothesis [BAH]), a theory that has been repeatedly challenged in recent years. We here use a full-factorial design with 2 developmental and 2 acclimation temperatures to test their effects on reproductive performance in the tropical butterfly, Bicyclus anynana. Competition experiments among virgin males from different thermal groups revealed that, at 20 degrees C, both groups acclimated to 20 degrees C achieved more than twice as many matings as those acclimated to 27 degrees C, whereas at 27 degrees C, only one group (acclimated to 27 degrees C) outperformed all others. Chill-Coma recovery times were also longer for butterflies that developed at higher temperatures, indicating that butterflies responded physiologically to the temperatures at which they were reared. Our results support the BAH at least in part, and do not support any alternative hypotheses.