Life-History Flexibility as a Strategy for Survival in a Variable Environment

At 15 0C, Nephelopsis obscura Verrill behaved as predicted for an iteroparous species, decreasing the rate of energy allocation to reproduction as ration declined. At 200C, under high ration, N. obscura deviated from predictions for both iteroparous and semelparous species by reducing the rate of energy allocation to reproduction at high rations. This temperature-related shift of energy allocation to reproduction is explained in terms of the relative mortality risks associated with breeding at 15 0C and 20 0C, and shows that N. obscura has a flexible life-history strategy, which is an adaptive response to breeding in a variable environment. Key-words: life history, phenotypic plasticity, energy budget, reproductive costs, bet hedging