The Heat Resistance of Some Anuran Tadpoles (Hylidae & Pelobatidae)
Brown HA. 1969. The Heat Resistance of Some Anuran Tadpoles (Hylidae & Pelobatidae). Copeia. 1969(1):138-147
Survival times of anuran tadpoles representing four species of two genera in the families Hylidae and Pelobatidae were determined at high temperatures. Heat resistance was studied by acclimating tadpoles to a constant temperature and determining the time to 50% survival after direct transfer to constant, high temperatures. Results indicate that thermal acclimation influences heat resistance, and that heat resistance correlates with the species' geographic distribution and breeding habits. Tadpoles of the tropical treefrog, Hyla septentrionalis, and desert spadefoot toad, Scaphiopus couchii, were the most heat resistant; tadpoles of the western spadefoot toad, S. hammondii, from California were the next most heat resistant, and tadpoles of the Pacific treefrog, H. regilla, were the least resistant. Geographic variation of tadpole temperature adaptations was studied in S. hammondii by comparing the heat resistance of control and hybrid tadpoles made from crosses between California and Arizona populations. The results are related to questions of geographic variation and speciation in this species.