Age-specific survival in the socially monogamous alpine marmot (<i>Marmota marmota</i>): evidence of senescence

Berger, Vérane; Lemaître, Jean‐François; Dupont, Pierre; Allainé, Dominique; Gaillard, Jean‐Michel; Cohas, Aurélie

doi:10.1093/jmammal/gyw028

Cited by 18 publications

(26 citation statements)

References 63 publications

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“…As expected, annual fitness presents a quadratic pattern for dominant individuals of both sexes, with the annual fitness increasing until approximately 7 years of age and decreasing thereafter. The decline in fitness observed after 7 years of age is in agreement with actuarial senescence occurring between 6 and 8 years of age (Berger et al., ). The curvature seems to be slightly steeper for dominant females than for dominant males, with the annual dominant females' fitness increasing faster but also decreasing faster than males'.…”

Section: Discussionsupporting

confidence: 81%

“…We calculated annual individual fitness p ti following Equation and tested whether annual fitness of alpine marmots varied with age. We expected annual fitness to increase in the first years of age because of low juvenile survival and progressive access to reproduction (marmots are sexually mature at 2 years of age, Allainé & Theuriau, ) and to decrease in older ages because of senescence (Berger et al., ). Therefore, we accounted for a quadratic effect of age on fitness in our model.…”

Section: Methodsmentioning

confidence: 99%

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Testing determinants of the annual individual fitness: An overall mean mixture model for de‐lifing data

et al. 2017

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The de‐lifing method (Coulson et al., 2006, Proceedings of the Royal Society of London B: Biological Sciences, 273, 547), though very promising for studying ecological and evolutionary changes, has been scarcely used to identify factors influential on fitness. Through simulations representative of a variety of iteroparous species, we establish that a two‐component normal mixture usually provides a much better representation of de‐lifing data than the single normal distribution assumed in classical linear models. To test determinants of the annual individual fitness, we propose the overall mean mixture model (O3M), a mixture model parameterised in terms of the overall mean of the mixture distribution. We examine the gain in performance and accuracy when using the O3M over classical linear models and bootstrap methods on simulated finite normal mixture distributions for different regression shapes and variance structure, and apply it to a real dataset to study how the annual individual fitness varies with age in alpine marmots. The O3M improves considerably the precision of the estimates and hence the power of the analysis. We discuss the adaptation of the O3M model to more complex distributions and advise on its use.

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Section: Discussionsupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Testing determinants of the annual individual fitness: An overall mean mixture model for de‐lifing data

et al. 2017

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“…The fact that males also experience greater energetic costs of hibernation could also be a factor (Arnold, ). However, despite senescence in male body mass, there is no clear sex difference in the intensity of survival senescence in this species, raising the possibility that male body mass declines influence fitness by acting through reproduction rather than survival (Berger et al, ). How commonly other non‐polygynous mammals in the wild display similar sex‐specific patterns of senescence is unknown as most information on monogamous taxa comes from birds or uses data from captive populations.…”

Section: Introductionmentioning

confidence: 94%

Sex‐independent senescence in a cooperatively breeding mammal

Thorley

Duncan

Sharp

et al. 2020

Journal of Animal Ecology

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Researchers studying mammals have frequently interpreted earlier or faster rates of ageing in males as resulting from polygyny and the associated higher costs of reproductive competition. Yet, few studies conducted on wild populations have compared sex‐specific senescence trajectories outside of polygynous species, making it difficult to make generalized inferences on the role of reproductive competition in driving senescence, particularly when other differences between males and females might also contribute to sex‐specific changes in performance across lifespan. Here, we examine age‐related variation in body mass, reproductive output and survival in dominant male and female meerkats, Suricata suricatta. Meerkats are socially monogamous cooperative breeders where a single dominant pair virtually monopolizes reproduction in each group and subordinate group members help to rear offspring produced by breeders. In contrast to many polygynous societies, we find that neither the onset nor the rate of senescence in body mass or reproductive output shows clear differences between males and females. Both sexes also display similar patterns of age‐related survival across lifespan, but unlike most wild vertebrates, survival senescence (increases in annual mortality with rising age) was absent in dominants of both sexes, and as a result, the fitness costs of senescence were entirely attributable to declines in reproductive output from mid‐ to late‐life. We suggest that the potential for intrasexual competition to increase rates of senescence in females—who are hormonally masculinized and frequently aggressive—is offset by their ability to maintain longer tenures of dominance than males, and that these processes when combined lead to similar patterns of senescence in both sexes. Our results stress the need to consider the form and intensity of sexual competition as well as other sex‐specific features of life history when investigating the operation of senescence in wild populations.

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“…Although exceptions exist (notably in monogamous species where both sexes display similar age‐dependent mortality patterns, see for example Berger et al. ), the sex‐bias in mortality pattern is particularly pronounced in mammals (e.g., Hill et al. ; Clutton‐Brock and Isvaran ; Austad ; Tidière et al.…”

Section: A Critical Appraisal Of Each Of the Nine Predictions Formulamentioning

confidence: 99%

“…As noted by Williams himself, higher mortality rates are observed in males in many taxa. Although exceptions exist (notably in monogamous species where both sexes display similar age-dependent mortality patterns, see for example Berger et al 2016), the sexbias in mortality pattern is particularly pronounced in mammals (e.g., Hill et al 2001;Clutton-Brock and Isvaran 2007;Austad 2011;Tidière et al 2015), especially when environmental conditions are harsh (Toïgo and Gaillard 2003). This bias is generally considered to be a direct consequence of the male involvement into intra-and/or intersexual competition (Bonduriansky et al 2008).…”

Section: Prediction 3 "Senescence Should Be More Rapid In Those Orgamentioning

confidence: 99%

The Williams' legacy: A critical reappraisal of his nine predictions about the evolution of senescence

2017

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Williams' evolutionary theory of senescence based on antagonistic pleiotropy has become a landmark in evolutionary biology, and more recently in biogerontology and evolutionary medicine. In his original article, Williams launched a set of nine "testable deductions" from his theory. Although some of these predictions have been repeatedly discussed, most have been overlooked and no systematic evaluation of the whole set of Williams' original predictions has been performed. For the sixtieth anniversary of the publication of the Williams' article, we provide an updated evaluation of all these predictions. We present the pros and cons of each prediction based on recent accumulation of both theoretical and empirical studies performed in the laboratory and in the wild. From our viewpoint, six predictions are mostly supported by our current knowledge at least under some conditions (although Williams' theory cannot thoroughly explain why for some of them). Three predictions, all involving the timing of senescence, are not supported. Our critical review of Williams' predictions highlights the importance of William's contribution and clearly demonstrates that, 60 years after its publication, his article does not show any sign of senescence.

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Age-specific survival in the socially monogamous alpine marmot (Marmota marmota): evidence of senescence

Cited by 18 publications

References 63 publications

Testing determinants of the annual individual fitness: An overall mean mixture model for de‐lifing data

Testing determinants of the annual individual fitness: An overall mean mixture model for de‐lifing data

Sex‐independent senescence in a cooperatively breeding mammal

The Williams' legacy: A critical reappraisal of his nine predictions about the evolution of senescence

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