Representations of the fitness landscape for female reproductive success (RS) as a function of pistil and stamen number in a flower under the condition when inbreeding depression is taken into account, predicted by generalized additive models (gam) using 87 individuals with a single flower (gray circles). The color gradient from white to red represents low to high predicted RS in terms of the number of seeds. Hypothetical linear trade-off lines between male and female functions were depicted by dotted (line a), dashed (line b), and solid lines (line c) for individuals of low, medium, and high resource status, respectively. Note that the slope of the trade-off lines is conceptual because we do not know the linearity and the actual trade-off ratio relating female to male units of allocation. Individuals with a given amount of resource are only able to explore the left and bottom part of the trade-off line on the fitness landscape. See also Figures S3–S6 and Table S3.
