Thermal dependency of calling performance in the eurythermic frog Colostethus subpunctatus

Only a few species of frogs, represented in four families (Bufonidae, Dendrobatidae, Hylidae, and Leptodactylidae), inhabit elevations above 3000 in in the tropical Andes, an environment that is characterized by dramatic thermal fluctuations. This degree of thermal variation forces Andean frogs to be eurythermic. One species in particular, Colostethus subpunctatus (family Dendrobatidae), is intriguing because it remains active year-round, calls from da vn to dusk, and experiences temperatures during calling activity that range from 6 C to more than 25 C. This frog, therefore, represents an excellent model for studding the effects of temperature on natural behavior in ectothermic vertebrates. In this study, we tested the hypothesis that eurythermy is associated with thermal independence of behavioral performance in C, subpunctatus. We recorded and analyzed vocalizations of more than 50 calling males from populations at 3500 in and 2000 m and at various temperatures. At least nine calls from each individual were selected at random, and characteristics, including calling rate, call duration, and peak frequency, were analyzed. Most temporal parameters were indeed affected by temperature, although thermal sensitivity was low. Some temporal and all spectral parameters exhibited interpopulational differences.