Energy accumulation and amphibian metamorphosis.

Timing of metamorphosis and size at metamorphosis were examined for Hyla crucifer under two densities in the laboratory. Results agree with previously known relationships for ranids and bufonids: at higher densities developmental time is longer, mean size at metamorphosis is smaller, and both parameters have greater variance than at lower densities. Density also affects energy accumulation: under ad libitum feeding conditions, an average individual raised at a higher density is able to accumulate less energy before metamorphosis than an average individual raised at a lower density. The suggestion is made that, in addition to growth and differentiation rates, energy accumulation may be important in determining when amphibian metamorphosis occurs.