Linkages among life-history components through time Carryover effects on the demography of a short-lived polycarpic plant

Abstract

Premise of the study Current reproduction in polycarpic plants may be affected by a wide variety of factors, including carryover or "historical" effects derived from environments experienced early in life and from previous investments in organ preformation or other life functions, such as growth or reproduction. Historical effects as determinants of plant reproductive success in a specific season have received considerably less attention than events during the current reproductive episode, especially for short-lived plants. Methods We used structural equation modeling to assess direct and indirect relations between past reproduction and both subsequent reproduction and growth in Helianthemum squamatum, a short-lived polycarpic plant. Additionally, we explored the effects of current reproduction on future survival (binomial variable) by using logistic regression. Key results Historical effects derived from previous growth positively affected current reproduction, suggesting the existence of a reproductive hierarchy in the population, in which some individuals are consistently better growers and seeders. The lack of effects of current reproduction on future reproduction, together with the existence of a negative effect on future survival, suggests that to invest maximally in reproduction at the expense of a short life span may be the optimal strategy for H. squamatum, a species inhabiting very unpredictable ecosystems. Conclusions Historical effects derived from past investments in growth or reproduction may have important consequences for current plant performance and may play an essential role in shaping life histories. © 2010 Botanical Society of America.