Metamorphic strategies of the Indian rice frog, Fejervarya limnocharis, in response to irrigation regimes

Organisms gain benefits from phenotypic plasticity by possessing traits better cope with environmental variations. Although cohort-dependent life-history strategy may be ubiquitous in amphibians, it is rarely studied. I investigated whether Indian rice frog, Fejervarya limnocharis, populations from cultivated fields with different irrigation regimes have differential cohort-dependent metamorphic strategies. I tested the hypothesis that populations inhabiting temporally disrupted breeding habitats would, while populations inhabiting temporally constant breeding habitats would not show cohort-dependent metamorphic strategies in response to seasonal temperature variation. I assessed cohort-dependent strategies by comparing metamorphic weight, age, and growth rate between spring and summer cohorts in response to low and high temperatures in a factorial common garden experiment. The results showed that the plasticity of metamorphic weight and age were both very extensive in the Indian rice frog. Tadpoles from disrupted irrigation (rice paddy) populations had cohort-dependent metamorphic strategies. In contrast, tadpoles from constant irrigation (water bamboo field) populations did not show cohort-dependent metamorphic strategies. More research on cohort-dependent life-history traits is badly needed to further our understanding the evolution of life history strategies.