THE EFFECT OF POLLEN LIMITATION ON PLANT REPRODUCTIVE SYSTEMS AND THEMAINTENANCE OF SEXUAL POLYMORPHISMS

Insufficient pollination can affect the reproductive output and the ra te of outcrossing of individual plants. We use a phenotypic model to e xplore the effect of pollen limitation on the evolution of plant repro ductive systems. Compared to situations without pollen limitation, we show that conditions for the stability of different reproductive syste ms can change under pollen limitation: hermaphrodites are maintained u nder a larger set of conditions at the expense of unisexual types, esp ecially males. We also show that trioecy, i.e., coexistence of hermaph rodites, males and females, can be evolutionarily stable, which is not the case in the absence of pollen limitation.