Effects of pollinator behavior and pollen carryover on patterns of multiple paternity within fruits

Background/Question/Methods . In many Angiosperm species individual fruits contain a mixture of half- and full- siblings, reflecting successful pollination by several fathers. This multiple paternity within fruits often results from simultaneous deposition of mixed pollen loads due to pollen carryover. In some species sequential probes bring in pollen from additional donors. To better understand the mechanisms of multiple paternity we developed a theoretical framework which links the dynamics of pollen transport to patterns of paternity within fruits.

Results/Conclusions . We combined models of pollen carryover with observed pollinator movement patterns to generate predicted levels of multiple paternity within fruits. This 'sire profile' model predicts that flowers on larger displays, which are subject to higher levels of geitonogamous pollination, will have lower levels of multiple paternity. It also predicts that species with more extensive pollen carryover will have higher levels of multiple paternity. We compared the quantitative predictions of this model with observed levels of multiple paternity in bumble bee-pollinated Mimulus ringens, which has restricted carryover, and hummingbird-pollinated Ipomopsis aggregata, which has more extensive carryover. The model correctly predicts that the effective number of mates is higher in Ipomopsis aggregata than in Mimulus ringens. This work extends our knowledge of the mechanisms determining plant mating patterns, and helps to unite distinct approaches to the study of pollination ecology.