Offspring Quality and the Polygyny Threshold: "The Sexy Son Hypothesis"

  title={Offspring Quality and the Polygyny Threshold: "The Sexy Son Hypothesis"},
  author={Patrick J. Weatherhead and Raleigh J. Robertson},
  journal={The American Naturalist},
  pages={201 - 208}
An expansion of the Orians-Verner model for the evolution of polygyny has been made to explain evidence contradictory to that model. By separating the individual quality of the male from the quality of his territory and assuming that male offspring will at least in part inherit the individual qualities of their father, it was postulated that females mating with "attractive" males and suffering reduced reproductive success could ultimately gain an advantage through the success of their "sexy… 

Offspring Quality and the Polygyny Threshold: A New Model for the "Sexy Son" Hypothesis

Consideration of the effect of reproduction over subsequent generations indicates that there is a limit to the number of generations over which a polygynously mated female can recoup an initial reproductive loss.

The neglected role of individual variation in the sexy son hypothesis

It is argued that lack of support could be related to the SSH formulation of the polygyny threshold as a population-level mechanism making the female choice of a polygynous male either advantageous or disadvantageous regardless of any other difference between potential mates.

Nest Predation Lowers the Polygyny Threshold: A New Compensation Model

A model is presented showing that the rate of nest losses, in the range normally found among passerines, might favor the fitness of secondary females more than that of monogamous females, thus decreasing the cost of selecting mated males.

Evolution of Female Choice and Male Parental Investment in Polygynous Species: The Demise of the "Sexy Son"

These models address the "sexy son" hypothesis of Weatherhead and Robertson (1979), which contends that selection can create an equilibrium at which females on the average mate with certain attractive types of males that give them inferior material resources and therefore decrease the females' immediate reproductive success.

A Diploid "Sexy Son" Model

A diploid sexy-son model is presented, demonstrating by counterexample that generalizations from haploid and additive polygenic models are not valid and the maximization principles derived from other models can be violated in the diploids case.

A Test of the “Sexy Son” Hypothesis: Sons of Polygynous Collared Flycatchers Do Not Inherit Their Fathers’ Mating Status

The results show that the sons of polygynously mated females fledged in poor condition and therefore did not inherit their father’s large forehead patch (a condition‐dependent display trait) or mating status, and polygynous pairing resulted in fewer recruited grandchildren than did a monogamous pairing.

Maternal characteristics and the production and recruitment of sons in the eastern kingbird (Tyrannus tyrannus)

The results support predictions of sex allocation theory: high-quality (heavy) females breeding when conditions were optimal for male recruitment produced an excess of sons.

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

This study suggests that harvesting, by generating a high proportion of young, small and unattractive mates, affects the secondary sex ratio due to differential allocation effects in females, and suggests sustainable management needs to consider not only the direct demographic changes due to harvest mortality and selection, but also the components related to behavioural ecology and opportunities for female choice.

Sexual conflict and the polygamy threshold




Longevity and the Evolution of Polygamy

A model emphasizing the role of longevity in the evolution of polygamy has been developed, with particular reference to the model postulated by Downhower and Armitage (1971). It is suggested that (1)

The Influence of Habitats on Mating Systems of North American Passerine Birds

Regardless of sex ratio, a polygynous mating is expected to be adaptive for the females as well as for the male, and marshes and prairies are more likely than forests to present the minimum requisite food supply and sufficiently great differences in available food between territories for selection to favor polygyny.


  • G. Bartholomew
  • Biology
    Evolution; international journal of organic evolution
  • 1970
The present paper undertakes to elaborate a verbal model based on ideas first suggested by Nutting (1891) and extended by Bertram (1940) and by Bartholomew (1952) and to place it more firmly in a documentable behavioral context.

The Evolution of Mating Systems in Birds and Mammals

Mating system theory must mesh with theoretical advances concerning the evolution of territoriality, parental behavior, and animal sociality and by including the appropriate theoretical work from these other areas, an integrated theory of vertebrate mating systems can be developed.

On the Evolution of Mating Systems in Birds and Mammals

Most cases of polygyny in birds, a group in which monogamy is the most common mating pattern, can be explained on the basis of the model, and those cases not apparently fitting into the predictions are clearly indicated.

Harem size, territory quality, and reproductive success in the redwinged blackbird (Agelaius phoeniceus)

It is suggested that some females were attracted to nest in territories in which their chances of successful reproduction were lower than if they had chosen other available territories, and postulate that females were choosing mates which would enhance their ultimate fitness rather than their immediate reproductive success.

Parental investment and sexual selection

The p,cnetics of sex nas now becn clarif ied, and Fishcr ( 1958 ) hrs produccd , n,od"l to cxplarn sex ratios at coDception, a nrodel recently extendcd to include special mccha_ nisms that operate under inbreeding (Hunrilron I96?).

Breeding Sex Ratios, Territoriality, and Reproductive Success in the Red-Winged Blackbird (Agelaius Phoeniceus)

  • C. Holm
  • Environmental Science, Biology
  • 1973
Data on sex rations, territoriality, and reproductive success were obtained from a breeding population of Red—winged Blackbirds, and were used to examine the adaptive significance of polygyny and

Adaptations of Polygynous Breeding in the Bobolink, Dolichonyx oryzivorus

A number of adaptations important in minimizing the disadvantages of a secondary status in female Bobolinks ( Dolichonyx oryzivorus ) have been discovered.

Seals and Group Selection

Seals have been shown to restrict recruitment in crowded populations because of gregarious and hierarchical behavior. Some authors have suggested that such behavior has evolved through group