SIZE-DEPENDENT ANALYSIS OF ALLOCATION TO SEXUAL AND CLONAL REPRODUCTION IN PENTHORUM SEDOIDES UNDER CONTRASTING NUTRIENT LEVELS

Reproductive output and reproductive allocation are important factors in the life history of any organism. In clonal plants, however, reproductive can refer to both sexual and asexual (clonal) replication. When investigating reproductive allocation, it is essential that the size of the plants studied be taken into account and that the direct analysis of ratios (e. g., fruit mass/vegetative mass) be avoided. Using methods that allow the testing of both a minimum size of reproduction and nonlinearity in the reproduction-size relationship, I investigated allocation of resources to both sexual (fruit mass) and clonal (stolon mass, ramet mass, and ramet number) reproduction in Penthorum sedoides under two nutrient treatments and over two generations. Allocation to sexual reproduction was predicted to be higher in the control treatments, while allocation to clonal reproduction should be higher in the nutrient-enriched treatment, in an effort to produce the most fit offspring in a given environment. The hypothesis that allocation to clonal growth would increase in high-nutrient environments was supported by the results for stolon and ramet mass but not for ramet number. The hypothesis that sexual allocation would increase in resource-poor environments was supported only in the second year of the experiments.