MINER, Benjamin G; Univ. of California, Davis: Effects of environmental variation on the evolution of phenotypic plasticity

The ability of an organism to change its phenotype in response to environmental (i.e. phenotypic plasticity) is ubiquitous in nature. In many cases phenotypic plasticity is adaptive and allows individuals of a population to cope with environmental variation. Although many theoretical studies have investigated when phenotypic plasticity is favored over a fixed phenotype, few studies have considered how plasticity evolves in environments with different amounts of variation. The few studies that have suggest that populations that experience more environmental variation should evolve a reaction norm (i.e. the relationship between the phenotype and the environment of a genotype) with a steeper slope. I further explored this question with an optimality model. I compared the fitnesses of reaction norms with different slopes in environments with different amounts of variation. Surprisingly, I did not find the relationship between the slope and the amount of environmental variation expected from previous studies. I therefore investigated whether the shape of the reaction norm was affected by the amount of environmental variation. The results for the shape of the reaction norm were quite different than those for the slope, and suggest that the shape, not the slope, of the reaction norm should be affected by the amount of environmental variation. In addition, I will present an explanation for the discrepancy between the results of my model and the results of previous studies. My model suggests that reaction norms and therefore plasticity should evolve in response to environmental variation fundamentally different than previous thought.