Selective advantage of irreversible and reversible phenotypic plasticity

A recent model on phenotypic plasticity is extended so that reversible and irreversible plasticity can be compared. It is assumed that the plastic organism receives an environmental cue that induces a change of the phenotype. Complete and incom-plete information are treated as two extreme cases of the reliability of those cues. Rela-tive fitness is calculated depending on the difference between inducing and non-induc-ing states of the environment and its coefficient of variation, on the time pattern and on the relative length of the inducing environment. In addition, fitness of reversible plas-ticity depends on the time delays for changing the phenotype from non-induced to induced and back. Irreversible plasticity can successfully compete with reversible plas-ticity only if at least one of these time delays becomes large, irrespective of the reli-ability of environmental cues. For either complete or incomplete information, there are parameter regions in which irreversibility is advantageous.