The expression of demographic costs of reproduction varies among coexisting plants with different life history traits

Abstract

Abstract Demographic costs of reproduction in flowering plants should depend on life history and reproductive efforts, but how the expression of costs varies with life‐history traits is poorly understood. We experimentally increased and reduced reproductive effort (fruit production) to quantify demographic costs of reproduction in four coexisting species with contrasting growth forms (clonal vs. non‐clonal) and flower production (single‐ vs. multi‐flowered). We repeated the experiment for 3 years and measured the demographic rates the year after the treatment. In 2 years, we also quantified the costs of flower maintenance by contrasting the performance of non‐fruiting plants with intact flowers and plants with their flowers removed. Costs varied among species, in both magnitude and demographic rate affected. Costs of natural reproduction were expressed as reductions in size and fecundity next year, whereas increased reproduction additionally reduced sprouting probability. The magnitude of demographic costs of both reproduction and flower maintenance was highest in the non‐clonal, multi‐flowered species, and costs were more frequently detected in the two multi‐flowered species than in the single‐flowered ones. This may be explained by higher biomass allocation to reproductive parts and a longer flowering period in the former. Demographic costs of reproduction did not depend on clone size. Synthesis. These results document that demographic costs vary among coexisting species sharing similar niches and are associated with divergence in life‐history traits. Such trait‐dependent variation in costs may reduce competition among coexisting species and facilitate diversity.