The Evolution of Hermaphroditism Among Animals

Ghiselin, Michael T.

doi:10.1086/406066

Cited by 952 publications

(643 citation statements)

References 56 publications

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“…Heath (1977) has proposed that a limit in the capacity of brood chambers may explain the distribution of hermaphroditism, since such a fixed limit may make it profitable for an individual to pay the extra fixed costs of male structures and simultaneously reproduce as a male. He suggests that this may explain the observed association between brooding and hermaphroditism (see also Ghiselin, 1969). Since the model presented here does not consider limits on female reproductive potential, it is not directly applicable to Heath's ideas, but could easily be extended to incorporate them.…”

Section: A Fixed Costs Modelmentioning

confidence: 99%

Individual and population sex allocation patterns

Frank

1987

Theoretical Population Biology

161

127

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A variety of sex allocation models is considered in which (i) the reproductive returns on investment in males differ from the returns on investment in females, (ii) the amounts of resources available for reproduction vary in the population, (iii) the costs of making male and female reproductive structures differ, and (iv) the conception sex ratio may be fixed and there may be an initial minimum investment per offspring. Results of these models include quantatitive predictions for both individual-and population-level sex allocation, an opportunity to study the magnitude of changes in predicted patterns as key variables change, and therefore an analysis of the robustness of Fisher's equal investment theory. One example is that Fisher's argument is extremely robust for high fecundity organisms, but, in low fecundity organisms, is sensitive to differences between the sexes in reproductive returns on investment per offspring, a situation that occurs in many vertebrates to which Fisher's theory is often applied. A second example is that individual-and population-level patterns often depend strongly on the distribution of resources available for reproduction among individuals in the population. AcademicPress, Inc.

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Section: A Fixed Costs Modelmentioning

confidence: 99%

Individual and population sex allocation patterns

Frank

1987

Theoretical Population Biology

161

127

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“…However, its applicability has not been addressed in sessile or very low mobility sex-changing animals that lack any obvious social interactions. The SAH predicts that sex change will occur earlier in populations exhibiting slower growth rates and higher mortality rates (Ghiselin 1969;Warner 1975;Charnov 1979Charnov , 1982Iwasa 1991;Munday 2002;Munday et al 2006). The detailed data obtained on these parameters for the fungiid populations during 2004-2007 enabled us to test these hypotheses on these sessile corals, which in all probability lack social control of sex allocation (table 1).…”

Section: Introductionmentioning

confidence: 97%

Bidirectional sex change in mushroom stony corals

Loya

Sakai

2008

Proc. R. Soc. B.

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Sex change occurs when an individual changes from one functional sex to another. The direction of sex change occurs mainly from male to female (protandry) or vice versa (protogyny), but sometimes may be bidirectional (repetitive). Here, for the first time in stony corals, we report on a protandrous sex change exhibited by two mushroom corals, Fungia repanda and Ctenactis echinata, with the latter also exhibiting bidirectional sex change. Compared with C. echinata, F. repanda exhibited relatively earlier sex change, significantly slower growth and higher mortality rates, in accordance with sex-allocation theory. Sex ratio in both the species was biased towards the first sex. The bidirectional sex change displayed by C. echinata greatly resembles that of dioecious plants that display labile sexuality in response to energetic and/or environmental constraints. We posit that, similar to these plants, in the studied corals, sex change increases their overall fitness, reinforcing the important role of reproductive plasticity in scleractinian corals in determining their evolutionary success.

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“…This makes them ideally suited for environments in which mate availability and gender are unpredictable (Ghiselin 1969) or reproductive gains show diminishing returns in at least one gender (Charnov 1979). Yet, hermaphrodites also seem to face unusual problems.…”

Section: Introductionmentioning

confidence: 99%

Sexual selection favors harmful mating in hermaphrodites more than in gonochorists

Michiels

Koene

2006

Integrative and Comparative Biology

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Synopsis Hermaphroditic animals often exhibit mating mechanisms that seem more damaging than those in species with separate sexes. Our analyses indicate that this difference is real. While females only remate when the benefit is positive, hermaphrodites remate even when this implies losing female fitness. This occurs because hermaphrodites can outweigh losses in the female function by gaining paternity. In an extended model we ask whether this favors the evolution of more male harm in hermaphrodites. When male harm only suppresses remating in the receiver it neither evolves in hermaphrodites nor in gonochorists. However, when male harm is coupled to a fertilization advantage, it evolves in both forms of gender expression with the highest levels in hermaphrodites. Hence, hermaphrodites are more prone to be caught in costly escalations than gonochorists. We discuss the implications for the evolution of gender expression in animals and plants.

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The Evolution of Hermaphroditism Among Animals

Cited by 952 publications

References 56 publications

Individual and population sex allocation patterns

Individual and population sex allocation patterns

Bidirectional sex change in mushroom stony corals

Sexual selection favors harmful mating in hermaphrodites more than in gonochorists

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