Experimental and theoretical support for costs of plasticity and phenotype in a nematode cannibalistic trait

Developmental plasticity is the ability of a genotype to express multiple phenotypes under different environmental conditions and has been shown to facilitate the evolution of novel traits. However, while the associated cost of plasticity, i.e., the loss in fitness due to the ability to express plasticity in response to environmental change, and the cost of phenotype, i.e., the loss of fitness due to expressing a fixed phenotype across environments, have been theoretically predicted, empirically such costs remain poorly documented and little understood. Here, we use a plasticity model system, hermaphroditic nematode Pristionchus pacificus, to experimentally measure these costs in wild isolates under controlled laboratory conditions. P. pacificus can develop either a bacterial feeding or predatory mouth morph in response to different external stimuli, with natural variation of mouth-morph ratios between strains. We first demonstrated the cost of phenotype by analyzing fecundity and devel...