Ejaculate quality in spotted hyenas: intraspecific variation in relation to life-history traits

Curren, Leslie J.; Weldele, Mary L.; Holekamp, Kay E.

doi:10.1644/12-mamm-a-057.1

Cited by 22 publications

(7 citation statements)

References 91 publications

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“…Our findings on male reproductive success differ from those of a previous study on spotted hyenas in the Maasai Mara in Kenya, which reported that philopatric males were less successful than dispersers (32). They further contradict the suggestions that philopatric male hyenas undergo physiological suppression (45,46) and are generally avoided by females as sires (32). These discrepancies may reflect real differences in hyena behavior and ecology between the two study populations, but they may also result from a difference in methodology.…”

Section: Discussioncontrasting

confidence: 99%

Why do some males choose to breed at home when most other males disperse?

et al. 2016

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Section: Discussioncontrasting

confidence: 99%

Why do some males choose to breed at home when most other males disperse?

et al. 2016

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“…In addition, some cows may not conceive because of failure by the bull to fertilize, which also would overestimate behavioral estimates of reproductive success. This may happen if older males become infertile or produce lower-quality sperm (Curren et al 2013). Also, if males have access to a large number of females and copulate often, the most prolific males can experience sperm depletion (Preston et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Behavioral versus genetic measures of fitness in bison bulls (Bison bison)

Mooring¹,

Penedo²

2014

J Mammal

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Accurate measures of fitness are important for both basic research on sexual selection and applied conservation actions to promote genetic diversity. For polygynous mammals, good estimates of male reproductive success are often critically important, but especially difficult to obtain. Because the genetic contribution of males is impossible to directly measure in the field, investigators have developed surrogate measures of fitness based on behavioral observations. Such measures are founded on the assumption that observed mating success can reliably predict reproductive success, yet only a few studies have been in a position to validate the accuracy of this assumption. We studied the bison herd at Fort Niobrara National Wildlife Refuge for 8 years, conducting intensive behavioral observations on breeding behavior during the rut (2003)(2004)(2005)(2006)(2007)(2008)(2009)) and collecting tissue samples of calves born the following year (2004-2010) for genetic paternity analysis. Our results reveal 2 major trends also observed in other studies: Estimates of mating success were positively correlated with reproductive success when we pooled the entire herd across age classes or years. However, copulatory success did a poor job of predicting the actual number of offspring sired by individual males. For example, 44% of observed matings did not result in the birth of offspring, and 60% of the copulations that did produce a calf did not accurately predict the sire bull. Generalized linear mixed model analysis revealed that observation of mating by a given bull in itself had no predictive power regarding likelihood of paternity, whereas total copulations per season, dominance status, and age of bull or dam significantly influenced the probability of siring offspring. Although use of behavioral data was unable to predict the sire for particular cows, it did give insights into patterns of reproductive success that use of genetic data alone could not provide, such as the role of alternate mating strategies and sperm competition for male reproductive success. We conclude that both behavioral and genetic measures of fitness are needed to understand sexual selection and meet the challenges faced by species of conservation concern.

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“…In support of this, studies testing the effect of age on sperm quality in humans have shown a general pattern of senescence, which includes a reduction in sperm velocity, motility and number, and an increase in abnormal morphology (reviewed in [6]). For non-human taxa, the results are mixed: some studies report a decline in sperm traits with age [7][8][9][10][11][12], while others demonstrate no significant change, or even an increase in sperm quality and quantity with age [13][14][15][16][17][18][19]. These differences among studies, sometimes even for those on the same species [11,17], raise questions about confounding factors that might be correlated with age, and could therefore obscure the direct effect of male age on sperm traits.…”

Section: Introductionmentioning

confidence: 99%

Male age alone predicts paternity success under sperm competition when effects of age and past mating effort are experimentally separated

et al. 2021

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Older males often perform poorly under post-copulatory sexual selection. It is unclear, however, whether reproductive senescence is because of male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. To date, very few studies have accounted for mating history and sperm storage when testing the effect of male age on sperm traits, and none test how age and past mating history influence paternity success under sperm competition. Here, we experimentally manipulate male mating history to tease apart its effects from that of age on ejaculate traits and paternity in the mosquitofish, Gambusia holbrooki . We found that old, naive males had more sperm than old, experienced males, while the reverse was true for young males. By contrast, neither male age nor mating history affected sperm velocity. Finally, using artificial insemination to experimentally control the number of sperm per male, we found that old males sired significantly more offspring than young males independently of their mating history. Our results highlight that the general pattern of male reproductive senescence described in many taxa may often be affected by two naturally confounding factors, male mating history and sperm age, rather than male age itself.

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Ejaculate quality in spotted hyenas: intraspecific variation in relation to life-history traits

Cited by 22 publications

References 91 publications

Why do some males choose to breed at home when most other males disperse?

Why do some males choose to breed at home when most other males disperse?

Behavioral versus genetic measures of fitness in bison bulls (Bison bison)

Male age alone predicts paternity success under sperm competition when effects of age and past mating effort are experimentally separated

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