Janet L. Over the last years, research has established that a sexual selection exists and is widespread in the plant and animal kingdoms; b it does not necessarily entail sexual dimorphism; even hermaphrodites have it; c it does not require intelligence or a sophisticated sense of esthetics; even tapeworms and plants choose mates; and d it does not require brawn or even mobility for competition; plants may compete for pollinators, and broadcast spawning invertebrates may also compete for matings. Although discussions of sexual selection often focus on sexual dimorphism, several phenomena that are commonly associated with sexual selection are widespread and highly developed in hermaphrodites. These phenomena include a bizarre and expensive courtship and copulatory behavior, b multiple mating and sperm competition, c rapid evolution of genitalia, d special structures associated with courtship, and e sexual polymorphism. The skewed breeding sex ratios associated with sequential hermaphroditism have long been recognized as contributory to sexual selection.
Intersex - Wikipedia
Hermaphrodites combine the male and female sex functions into a single individual, either sequentially or simultaneously. This simple fact means that they exhibit both similarities and differences in the way in which they experience, and respond to, sexual conflict compared to separate-sexed organisms. Here, we focus on clarifying how sexual conflict concepts can be adapted to apply to all anisogamous sexual systems and review unique or especially important aspects of sexual conflict in hermaphroditic animals. These include conflicts over the timing of sex change in sequential hermaphrodites, and in simultaneous hermaphrodites, over both sex roles and the postmating manipulation of the sperm recipient by the sperm donor. Extending and applying sexual conflict thinking to hermaphrodites can identify general evolutionary principles and help explain some of the unique reproductive diversity found among animals exhibiting this widespread but to date understudied sexual system. Conceptual and empirical work on sexual conflict is dominated by studies on gonochorists species with separate sexes e. The fundamental asymmetry from which sexual conflict emerges is ultimately rooted in the evolution of anisogamy, which may itself have resulted from a primordial sexual conflict over allocation to gamete provisioning.
Hermaphroditism , the condition of having both male and female reproductive organs. Hermaphroditic plants —most flowering plants, or angiosperms —are called monoecious, or bisexual. Hermaphroditic animals—mostly invertebrates such as worms , bryozoans moss animals , trematodes flukes , snails , slugs , and barnacles —are usually parasitic, slow-moving, or permanently attached to another animal or plant.
For example, the great majority of tunicates , pulmonate snails, opisthobranch snails , earthworms , and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites.