Life History Variation in Dioecious Plant Populations: A Case Study of Chamaelirium luteum

Abstract

Perhaps the most commonly acknowledged genetic polymorphism in animal populations is that of sexual dimorphism. Studies on this phenomenon in animal species have shown that sexual dimorphism influences almost every aspect of their ecology and evolution (e.g., Bartholemew 1970, Feduccia and Slaughter 1974, Jackson 1970, Morse 1968). Although perhaps not so conspicuous for plant species, sexual dimorphism can have far-reaching effects on their biology as well. Studies on sexual dimorphism in plants in the past have been largely limited to floral characteristics (Lloyd and Webb 1977), but over the past few years there has been a growing interest in manifestations of sexual dimorphism in plant life histories (Grant and Mitton 1979, Hancock and Bringhurst 1980, Lloyd and Webb 1977, Onyekwelu and Harper 1979, Wallace and Rundel 1979, Wilson 1979). In order to elucidate the role of life histories in the evolution of dioecious plant species, it is necessary to study how sexual dimorphism influences the life histories of males and females and, in turn, how sexual dimorphism in life history traits, such as mortality and fecundity, influences the relative roles of males and females in the population as a whole.