Data from: Distinct effects of pollinator-dependence and self-incompatibility on pollen limitation in South African biodiversity hotspots

Global synthesis indicates that limitation of plant fecundity by pollen receipt (pollen limitation) is positively related to regional plant diversity and is higher for self-incompatible than self-compatible species. While self-incompatible species are always dependent on pollinating agents, self-compatible species may be pollinator dependent or autofertile. This should cause variation in pollen limitation among self-compatible species, with lower pollen limitation in autofertile species because they do not depend on pollinators. We hypothesised that the intensity of pollen limitation in self-incompatible compared to pollinator-dependent self-compatible species should depend on whether pollen limitation is determined more by quantity versus quality of pollen received. We compared pollen limitation between these three groups using a dataset of 70 biotically pollinated species from biodiverse regions of South Africa. Comparison with a global dataset indicated that pollen limitation in the South African biodiversity hotspots was generally comparable to other regions, despite expectations of higher pollen limitation based on the global plant diversity-pollen limitation relationship. Pollen limitation was lowest for autofertile species, intermediate for self-incompatible species and highest for pollinator-dependent self-compatible species. This is consistent with increased pollen-quality limitation due to negative consequences of pollinator mediated self-pollination in pollinator dependent self-compatible species. However, there was also a higher frequency of plants with zygomorphic flowers, which were also more pollen limited, among pollinator-dependent self-compatible species, so we could not attribute differences exclusively to pollen-quality limitation. Nevertheless, our results indicate that comparative studies should control for both pollinator dependence and self-incompatiblity when investigating effects of other factors on pollen limitation.