Effects of pollination method on paternal success in Lesquerella fendleri (Brassicaceae)

Hand pollinations are frequently used to assess the postpollination success of different donors. We present evidence that the method used for hand pollinations can alter pollen germination rates and paternity of the resulting seeds. Two commonly used methods for hand pollination experiments are mixed pollinations, where pollen from several donors is physically mixed together, and adjacent pollinations, where pollen from one donor is close to, but not in physical contact with, pollen from other donors. These methods offer differing opportunities for pollen interaction, and for females to choose among mates. We found that the success of pollen donors in multidonor pollinations varied with pollination method in unpredictable ways across maternal plants. Pollen germination was significantly lower in adjacent pollinations, perhaps explaining some of the effects of pollination method on paternity. These results may yield insights on the factors influencing pollen success, and indicate that hand pollination experiments should employ pollination methods that mimic as closely as possible the natural arrival of pollen in nature.