Postpollination Selection and Male Fitness in Plants

Abstract

Postpollination events are often described as potential mechanisms for sexual selection in plants. The broadest interpretation of what constitutes sexual selection includes selection on both pollen (analogous to sperm competition in animals) and embryos as possible manifestations of male-male competition and/or female choice. Including selective embryo abortion as a mechanism for sexual selection is controversial because interactions among young progeny and their maternal parent are distinct from interactions among parental plants or their gametes. Nonetheless, I discuss mechanisms for both pre- and postfertilization selection, in part because of the practical difficulties of discriminating between the two. I focus on whether these processes result in differential mating success among pollen donors in natural populations. Evolutionary change occurs when such differences are due to traits controlled by additive genetic variation. Little evidence suggests that postpollination mechanisms affect male reproduc...