PHENOTYPIC PLASTICITY FOR OFFSPRING TRAITS IN POLYGONUM-PERSICARIA

This paper investigates the effects of parental environment and genoty pe on offspring provisioning, structure, and growth traits in the annu al plant Polygonum persicaria. Replicate offspring were studied from c loned individuals of five parental genotypes grown in high vs. low lig ht, soil moisture, and soil nutrients. Genotypic norms of reaction wer e 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 th at parental genotypes altered offspring traits in response to particul ar resource limits, such that offspring quality was maintained or enha nced despite parental resource deprivation. By maximizing the probabil ity 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, ev en this small sample revealed differences among parental genotypes in their response to environment. This may reflect the degree to which va riation in fitness-related offspring traits occurs within parents and hence is unavailable to selection.