Determinants of Metamorphic Timing in the Black-bellied Salamander, Desmognathus quadramaculatus

Abstract

Abstract We used two experiments to test the hypothesis that variation in growth rate, temperature, and thyroid hormone exposure will induce variation in metamorphic timing in the Black-bellied Salamander, Desmognathus quadramaculatus (Holbrook). In one experiment, second-year larvae (i.e., those approaching a metamorphic summer) were treated with high or low food and exposed to high or low temperature. Low temperature resulted in delayed metamorphosis, while food regime had no effect on metamorphic timing. In a second experiment, first-year larvae (i.e., those not expected to undergo natural metamorphosis during the experiment) were grown at two temperatures and treated with thyroid hormones or control supplements. Larvae at low temperature grew more slowly. Larvae treated with thyroid hormone failed to show any sign of metamorphosis compared to control larvae.