Darwinian fitness is determined by the outcome of allocations of energy and nutrients to plant growth, survival, and reproduction. Allocations to reproduction differ from allocations to growth and survival because the products of reproduction (pollen, ovules, and fruits) are dispersed away from the plant and so the resources used to produce them cannot be re-allocated. As a result, and because the total resource pool available to a plant is limited, allocations to reproduction can reduce future growth, reproduction, and/or survival, yielding fitness costs of reproduction. This study provides a novel approach to detecting the costs of reproduction through multiple reproductive currencies, including both biomass and nitrogen allocations and their temporal effects on current and future plant performance. My results demonstrate the environmental dependence of the costs of reproduction and show that under certain conditions, males can bear greater costs than females, contrary to the prevailing view.
Author Keywords: Cost of reproduction, dioecy, flower removal, life-history trade-offs, photosynthetic machinery, sexual dimorphism