Phenotypic plasticity for offspring traits in Polygonum persicaria

This paper investigates the effects of parental environment and genotype on offspring provisioning, structure, and growth traits in the annual plant Polygonum persicaria. Replicate offspring were studied from cloned individuals of five parental genotypes grown in high vs. low light, soil moisture, and soil nutrients. Genotypic norms of reaction were determined for ecologically important offspring traits. The effects on those traits of parental genotype, parental environment, and their interaction were tested by analysis of variance. The results showed that parental genotypes altered offspring traits in response to particular resource limits, such that offspring quality was maintained or enhanced despite parental resource deprivation. By maximizing the probability of offspring success, resource-deprived parental plants may partly offset the reduction in their fitness due to lower offspring number. Although overall patterns of plasticity were common to all parents, even this small sample revealed differences among parental genotypes in their response to environment. This may reflect the degree to which variation in fitness-related offspring traits occurs within parents and hence is unavailable to selection.