Pollen limitation is common—should it be? a comment on Rosenheim et al., “Parental optimism versus parental pessimism in plants: how common should we expect pollen limitation to be?”

Although several meta-analyses have indicated that pollen limitation of seed output is widespread and often severe in flowering plants, a theoretical model of Rosenheim et al. published in 2014 predicts otherwise. Their predictions of infrequent pollen limitation were based on estimated ratios between prefertilization and postfertilization costs that are likely to be unrealistically low and on an assumption about variance in ovule fertilization among plants that is likely to be unrealistically narrow. I show that the predictions of the model of Rosenheim et al. are sensitive to these assumptions. In particular, more realistic distributions of pollination variation yield predictions that are in better accord with empirical data. Pervasive pollen limitation therefore remains unsurprising, although the extent of lifetime pollen limitation remains an important frontier for research.