Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser?

Cameron, Elissa Z.; Linklater, Wayne L.; Stafford, Kevin J.; Minot, Edward O.

doi:10.1007/s002650050661

Cited by 121 publications

(96 citation statements)

References 30 publications

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“…Despite previously reported variation in birth rate and offspring survival between individual mares in this population in relation to age (32) and band type (33), such variation was not found among our smaller sample of focal mares. Also, social integration did not vary with mare age, band type, or dominance.…”

Section: Discussioncontrasting

confidence: 99%

“…The youngest mares are still in the process of dispersal and have yet to develop band fidelity (20), and therefore, most of these females were excluded from our analysis, because we used only mares with a stable band affiliation. Much of the variation due to age is due to the low rates of reproduction in the youngest mares (32). Band type influenced foaling success, confirming our previous research that showed that mares in multi-stallion bands are more protective of their foals than mares in single-stallion bands, possibly due to the risk of infanticide (33), and that they have lower reproductive success (6).…”

Section: Discussionsupporting

confidence: 77%

“…Mares were aged by tooth wear and eruption patterns (50, 51), because mare age can influence reproductive success in horses (31). Aging by tooth wear decreases in accuracy with increasing age (51), and therefore, we classified mares into the following age categories: young (3-5 years, before reaching their full reproductive potential) (52), midaged (6 -8 years), and old (at least 9 years) (32,53). Teeth were examined after horses had been gathered into purpose-built yards and restrained in a hydraulic crush.…”

Section: Methodsmentioning

confidence: 99%

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Social bonds between unrelated females increase reproductive success in feral horses

Cameron

Setsaas

Linklater

2009

Proc. Natl. Acad. Sci. U.S.A.

459

413

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In many mammals, females form close social bonds with members of their group, usually between kin. Studies of social bonds and their fitness benefits have not been investigated outside primates, and are confounded by the relatedness between individuals in primate groups. Bonds may arise from kin selection and inclusive fitness rather than through direct benefits of association. However, female equids live in long-term social groups with unrelated members. We present 4 years of behavioral data, which demonstrate that social integration between unrelated females increases both foal birth rates and survival, independent of maternal habitat quality, social group type, dominance status, and age. Also, we show that such social integration reduces harassment by males. Consequently, social integration has strong direct fitness consequences between nonrelatives, suggesting that social bonds can evolve based on these direct benefits alone. Our results support recent studies highlighting the importance of direct benefits in maintaining cooperative behavior, while controlling for the confounding influence of kinship.equid ͉ friendship ͉ social structure ͉ alliances ͉ sociality

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Social bonds between unrelated females increase reproductive success in feral horses

Cameron

Setsaas

Linklater

2009

Proc. Natl. Acad. Sci. U.S.A.

459

413

View full text Add to dashboard Cite

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“…The effect of fetal sex may diminish to some extent among multiparous females due to the aggregate effects on mammary gland architecture of sequential gestations of different fetal sexes. Alternatively, maternal investment tactics may change as a function of residual reproductive value [68] or targeted effort during critical developmental windows [69].…”

Section: Discussionmentioning

confidence: 99%

Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex

Hinde

Carpenter

Clay

et al. 2014

Preprint

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Mammalian females pay high energetic costs for reproduction, the greatest of which is imposed by lactation. The synthesis of milk requires, in part, the mobilization of bodily reserves to nourish developing young. Numerous hypotheses have been advanced to predict how mothers will differentially invest in sons and daughters, however few studies have addressed sexbiased milk synthesis. Here we leverage the dairy cow model to investigate such phenomena. Using 2.39 million lactation records from 1.49 million dairy cows, we demonstrate that the sex of the fetus influences the capacity of the mammary gland to synthesize milk during lactation. Cows favor daughters, producing significantly more milk for daughters than for sons across lactation. Using a sub-sample of this dataset (N = 113,750 subjects) we further demonstrate that the effects of fetal sex interact dynamically across parities, whereby the sex of the fetus being gestated can enhance or diminish the production of milk during an established lactation. Moreover the sex of the fetus gestated on the first parity has persistent consequences for milk synthesis on the subsequent parity. Specifically, gestation of a daughter on the first parity increases milk production by ,445 kg over the first two lactations. Our results identify a dramatic and sustained programming of mammary function by offspring in utero. Nutritional and endocrine conditions in utero are known to have pronounced and long-term effects on progeny, but the ways in which the progeny has sustained physiological effects on the dam have received little attention to date.

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“…The age data distinguished between the older females and those born into the population, thus presenting an opportunity to assess if younger females are more or less successful at raising young. In some species, disparity in reproductive success due to age is most evident for young females, especially when full reproductive potential is not reached until well after age of first birth (Clutton-Brock 1984, Cameron et al 2000. Thus, including an age parameter in this analysis that distinguishes young females was considered useful.…”

Section: Mother Agementioning

confidence: 99%

Factors influencing heterogeneity in female reproductive success in a Critically Endangered population of bottlenose dolphins

Brough

Henderson²,

Guerra³

et al. 2016

Endang. Species. Res.

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For threatened species or populations, variation in reproductive success among females may be explicitly linked with vulnerability to extinction. Thus, an understanding of factors that may cause variability in reproductive success is important. The population of bottlenose dolphins in Doubtful Sound, New Zealand, has a recent history of rapid population decline and low calf survival rates. A previous study has shown high variability in calf survival among multiparous females. This study addresses the factors that seem most important in explaining variation in calf survival and thus reproductive success among females in this population. Reproductive data were sourced from a long-term photo-identification dataset, which allowed tracking the fate of 49 calves born into the population between 1995 and 2012. General linear mixed models combined with model averaging were used to assess how birth timing, maternal size, age and potential anthropogenic impacts contributed to variation in calf survival. Models show that a female's size and her ability to give birth at an optimum time in the calving season are significant predictors of calf survival to an age of 1 and 3 yr. This is the first study to demonstrate how birth timing and mother size are correlated with female reproductive success in a cetacean species. These results confirm the importance of demographic stochasticity and reproductive heterogeneity in small, threatened marine mammal populations.

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Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser?

Cited by 121 publications

References 30 publications

Social bonds between unrelated females increase reproductive success in feral horses

Social bonds between unrelated females increase reproductive success in feral horses

Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex

Factors influencing heterogeneity in female reproductive success in a Critically Endangered population of bottlenose dolphins

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