Testing the Adaptive Plasticity Hypothesis for Plant Responses to Neighbors

Abstract The hypothesis that phenotypic plasticity is adaptive has rarely been tested explicitly. To support this hypothesis, it is necessary to demonstrate that the phenotype induced in each environment experienced by an organism has a high relative fitness in that environment. In plants, phytochrome‐mediated responses to the reduced ratio of red: far‐red light (R:FR) characteristic of dense vegetation have frequently been assumed to be …