Hermaphroditism is rare and phylogenically in decline among animal species. The evolutionary basis for this development is not well understood. This paper focusses on self-incompatible simultaneous hermaphroditism in animals. It proposes that such hermaphroditism is not stable in sufficiently heterogeneous populations, suggesting a possible reason for why hermaphroditism is rare among evolved a...

References 107 Abstract Genetic and environmental factors may interact to control sex determination in fishes. A common pattern of initial female differentiation and subsequentmale transformation before maturation in non-hermaphroditic fishes and after maturation in sequentially hermaphroditic fishes has suggested that changes in developmental timing may be responsible for the evolution of vari...

The low density model produced by Tomlinson to describe the evolution of hermaphroditism is shown to undervalue the level of gain to hermaphrodites in small populations. This model is revised to take into account gains for hermaphrodites in breeding units where not only one but where both sexes of gonochorists occur. This revision permits hermaphrodites significant gains in populations as large...

has celebrated. This poetical and transcendental idea has so dominated the lay and scientific mind that even now the question of hermaphroditism in the mammalia is discussed and supported by the description of specimens with alleged ova and spermatozoa in a common sex gland, or of those where the opposite sex-duct element is unduly represented at the expense, we shall see, of the potent normal ...

True hermaphrodites are animals of equivocal sex in which both male and female gonads develop simultaneously in the same individual. The frequency of true hermaphroditism is relatively higher in pigs than in other domestic animals. Two Korean pigs were diagnosed with true hermaphroditism showing ovotestes, epididymides, a penis and uteri. The testicular tissues consisted of Sertoli cells that w...

The divergence times of lizardfishes (Euteleostei: Aulopiformes) are estimated utilizing a Bayesian approach in combination with knowledge of the fossil record of teleosts and a taxonomic review of fossil aulopiform taxa. These results are integrated with a study of character evolution regarding deep-sea evolutionary adaptations in the clade, including simultaneous hermaphroditism and tubular e...

Bateman's principle states that reproductive success is limited a) in females by the resources available for egg production; and b) in males, only by access to females and/or eggs. The principle has been used to generate predictions for two aspects of hermaphroditism; a) the advantage of hermaphroditism and b) sexual conflict. Comparing these predictions to the empirical data offers tests of Ba...