Benefits of phenotypic plasticity for population growth in varying environments

Phenotypic plasticity refers to the capacity of the same organisms to exhibit different characteristics under varied environmental conditions. A plastic developmental program allows organisms to sense environmental cues in early stages of life and express phenotypes that are better fitted to environments encountered later in life. This is often considered an adaptive strategy for living in varying environments as long as the plastic response is sufficiently fast, is accurate, and is not too costly. However, despite direct costs of maintaining plasticity and producing phenotypes, a fundamental constraint on the benefit of phenotypic plasticity comes from the predictability of the future environment based on the environmental cues received during development. Here, we analyze a model of plastic development and derive the limits within which this strategy can promote population growth. An explicit expression for the long-term growth rate of a developmentally plastic population is found, which can be decomposed into several easily interpretable terms, representing the benefits and the limitations of phenotypic plasticity as an adaptation strategy. This growth rate decomposition has a remarkably similar form to the expressions previously obtained for the bet-hedging strategy, in which a population randomly diversifies into coexisting subgroups with different phenotypes, implying that those evolutionary strategies may be unified under a common general framework.