Life History Constraints Facilitate the Evolution of Androdioecy and Male Dwarfing
“Sex allocation” is the allocation of resources between male and female functions, while “life history strategy” is one between growth and reproduction (and survival). Although life history strategy and sex allocation theories have commonly been studied separately, they interact strongly since both study the optimal allocation of resources available for each individual. For example, individuals with different life history schedules may also differ in terms of sexuality. To illustrate how such life history/sex allocation polymorphism evolves to form various sexual systems such as androdioecy (the coexistence of males and hermaphrodites), I introduce simple mathematical models that consider how constraints (temporal or spatial limitations) on the decision-making of life history path facilitate the coexistence of individuals with different schedules of resource allocation (life history and sexuality), focusing on androdioecious barnacles (dwarf males + hermaphrodites) as an example. The temporal limitation model shows that an unlucky individual who enters an old microhabitat should become a dwarf male to make the best of a bad situation. Although the individual’s fitness could be higher if it has sufficient time for growth in a young microhabitat, becoming a dwarf male is the optimal tactic for the unlucky individual. The coexistence of different sexualities was also explained by the spatial limitation model, which assumes life history constraints among based on the microscopic environmental conditions.
KeywordsDioecy Androdioecy Hermaphrodite Dwarf male Sex allocation Life history
The models introduced in this chapter were results of collaborative works with Y. Iwasa, K. Sawada, and Y. Yusa. I am very grateful to E.L. Charnov and J.T. Høeg for the valuable discussion about barnacles’ sexual systems and H. Kokko for helpful comments. I thank J.L. Leonard for encouraging me to write this chapter.
- Buhl-Mortensen L, Høeg JT (2006) Reproduction and larval development in three scalpellid barnacles, Scalpellum scalpellum (Linnaeus 1767), Ornatoscalpellum stroemii (M. Scars 1859) and Arcoscalpellum michelottianum (Seguenza 1876), Crustacea: Cirripedia: Thoracica: implication for reproduction and dispersal in the deep sea. Mar Biol 149:829–844CrossRefGoogle Scholar
- Charnov EL (1982) The theory of sex allocation. Princeton University Press, PrincetonGoogle Scholar
- Charnov EL (1987) Sexuality and hermaphroditism in barnacles: a natural selection approach. In: Southward AJ (ed) Barnacle biology. Crustacean issues, vol 5. A. A. Belkema, Rotterdam, pp 89–103Google Scholar
- Crisp DJ (1983) Chelonobia patula (Ranzani), a pointer to the evolution of the complemental male. Mar Biol Lett 4:281–294Google Scholar
- Darwin C (1851) A monograph on the sub-class Cirripedia, The Lepadidae, vol 1. The Ray Society, LondonGoogle Scholar
- Ghiselin MT (1974) The economy of nature and the evolution of sex. University of California Press, BerkeleyGoogle Scholar
- Kolbasov GA, Zevina GB (1999) A new species of Paralepas (Cirripedia: Heteralepadidae) symbiotic with Xenophora (Mollusca: Gastropoda); with the first complemental male known for the family. Bull Mar Sci 64:391–398Google Scholar
- Ó Foighil D (1985) Form, function, and origin of temporary dwarf males in Pseudopythina rugifera (Carpenter, 1864) (Bivalvia: Galeommatacea). Veliger 27:245–252Google Scholar
- Stearns SC (1992) The evolution of life histories. Oxford University Press, OxfordGoogle Scholar