Effect of Habitat Drying on Age and Size at Metamorphosis in Indian Painted Frog, Uperodon taprobanicus (Anura: Microhylidae)

Anurans have complex life cycles. The key metamorphic traits in anurans are larval duration and size at metamorphosis. In most of the anurans, these two metamorphic traits are largely influenced by several biotic and abiotic factors but mainly by habitat drying. We studied the influence of habitat drying on larval duration and size at emergence in Uperodon taprobanicus under laboratory conditions. Freshly hatched tadpoles (Gosner stage 19) were exposed to decreasing water levels (gradually or rapidly) up to the beginning of metamorphic climax stage (MC, Gosner stage 42; emergence of forelimbs). The control group was reared in constant water levels. Tadpoles reared in decreasing water levels (gradually or rapidly) reached MC and completed larval duration earlier and metamorphosed at a smaller size than those reared in constant water levels. Further, tadpoles experiencing rapid depletion of water reached MC and completed larval duration earlier and also metamorphosed at smaller size than those experiencing gradual depletion in water levels. Thus, tadpoles of U. taprobanicus showed adaptive plasticity in metamorphosis to habitat drying. The study shows that U. taprobanicus tadpoles are capable of developmental plasticity and exposed to decrease in water levels, the trade-off between growth and development is in favour of development, resulting in early metamorphosis at a smaller size.