Human sperm competition: testis size, sperm production and rates of extrapair copulations
@article{Simmons2004HumanSC,
title={Human sperm competition: testis size, sperm production and rates of extrapair copulations},
author={Leigh W. Simmons and Ren{\'e}e C. Firman and Gillian Rhodes and Marianne Peters},
journal={Animal Behaviour},
year={2004},
volume={68},
pages={297-302}
}
111 Citations
Sperm Competition in Humans: Mate Guarding Behavior Negatively Correlates with Ejaculate Quality
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It is found that men who performed fewer mate guarding behaviors produced higher quality ejaculates, having a greater concentration of sperm, a higher percentage of motile sperm and sperm that swam faster and less erratically.
Sperm Competition Risk and Sexual Coercion Predict Copulatory Duration in Humans
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A man whose romantic partner is sexually unfaithful is at risk of sperm competition and cuckoldry—unwitting investment in offspring to whom he is genetically unrelated. Men, therefore, may have…
The evolution of expenditure on testes
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- 2016
Sexual cascade logic suggests that gonad expenditure should be high and equal for the two sexes soon after the early evolution of anisogamy, but should diverge widely through evolutionary time, with RTS reducing notably in those taxa that have evolved advanced mobility and internal fertilization.
Rapid evolution of testis size relative to sperm morphology suggests that post‐copulatory selection targets sperm number in Anolis lizards
- BiologyJournal of evolutionary biology
- 2019
The results suggest that sperm production is the primary target of post‐copulatory sexual selection in this lineage of Anolis lizards, and testis size has evolved faster than any aspect of sperm morphology or body size, supporting the hypothesis that post-copulatorySexual selection acts more strongly upon sperm production than upon sperm morphology.
Men Ejaculate Larger Volumes of Semen, More Motile Sperm, and More Quickly when Exposed to Images of Novel Women
- Biology, Psychology
- 2015
It is suggested that human males ejaculate more quickly and invest more in ejaculates with novel females when exposed to a novel female.
Of mice and women: advances in mammalian sperm competition with a focus on the female perspective
- BiologyPhilosophical Transactions of the Royal Society B
- 2020
This review identifies shortcomings in the understanding of the specific mechanisms by which female mammals ‘select’ sperm and demonstrates how mammals will continue to be effective animal models for studying both evolutionary and facultative responses to sperm competition.
The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition.
- BiologyJournal of human evolution
- 2012
The relationship of body condition, superoxide dismutase, and superoxide with sperm performance
- BiologyBehavioral Ecology
- 2019
Sperm competition theory predicts a negative correlation between somatic investment and traits that aid in pre- and postcopulatory sexual selection. Sperm performance is critical for postcopulatory…
References
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It is demonstrated that testis mass is related positively to the level of extra-pair paternity, after controlling for body size and phylogeny, and it is argued that selection has favoured increased testismass in situations of more intense sperm competition in order to retaliate against copulations by rival males.
Human sperm competition: ejaculate adjustment by males and the function of masturbation
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M masturbation is a male strategy to increase sperm fitness without increasing sperm numbers in the female tract as a function of risk of sperm competition; female reproductive value; and optimum partitioning of ejaculates between successive in-pair copulations.
Sperm Competition in Fishes: The Evolution of Testis Size and Ejaculate Characteristics
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It is found that both the gonadosomatic index and sperm numbers increase with intensity of sperm competition across species but that sperm length decreases, which does not fit predictions of current sperm competition theory.
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A significant positive relationship between social group size and testis mass is found across 31 species of microchiropteran bat and comparative analysis of independent contrast (CAIC) finds it positively related to sperm competition risk in a wide range of taxa.
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Human sperm competition: ejaculate manipulation by females and a function for the female orgasm
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Sperm competition: Motility and the midpiece in primates
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The results indicate that sexual selection by sperm competition has influenced the evolution of a specific component of male-gamete morphology, the volume of the sperm midpiece, in primate species with multiple-partner mating systems.
Sperm quality in the alternative reproductive tactics of Atlantic salmon: the importance of the loaded raffle mechanism
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The results establish that, in sperm competition with dominant males, parr males may compensate for behavioural subordinance by producing physiologically superior spermatozoa.