Maternal effects of herbivory in Impatiens capensis

Abstract

Maternal effects of herbivory for fitness-related traits of offspring, especially those traits that are expressed later in a plant's life, have rarely been studied. To better understand how herbivory to the maternal plant influences traits of its progeny and whether this depends on the mating system that produced the seed or the growth environment of the seedling, we examined maternal effects of herbivory in Impatiens capensis. Impatiens capensis is well suited to this study because it exhibits a mixed mating system by producing obligately selfing cleistogamous flowers and facultatively outcrossing chasmogamous flowers on a single plant. In a natural I. capensis population, we manipulated maternal herbivory and collected seeds from cleistogamous and chasmogamous flowers and assessed their fitness in the presence or absence of intraspecific competitors in the greenhouse. We found that maternal herbivory had positive effects for many offspring traits but the magnitude of the maternal effect depended on the offspring competitive context. In addition, for offspring biomass and total flower production, the expression of maternal effects varied with seed source (i.e., chasmogamous or cleistogamous flower). Our results demonstrate that maternal herbivory has consequences for the next generation that persist throughout the offspring life cycle, indicating that there may be important demographic consequences of maternal effects.