@article{HaemaelaeinenDammhahnAujardetal.2014,
  author    = {Haemaelaeinen, Anni and Dammhahn, Melanie and Aujard, Fabienne and Eberle, Manfred and Hardy, Isabelle and Kappeler, Peter M. and Perret, Martine and Schliehe-Diecks, Susanne and Kraus, Cornelia},
  title     = {Senescence or selective disappearance? Age trajectories of body mass in wild and captive populations of a small-bodied primate},
  series = {Proceedings of the Royal Society of London : B, Biological sciences},
  volume    = {281},
  journal   = {Proceedings of the Royal Society of London : B, Biological sciences},
  number    = {1791},
  publisher = {Royal Society},
  address   = {London},
  issn      = {0962-8452},
  doi       = {10.1098/rspb.2014.0830},
  pages     = {10},
  year      = {2014},
  abstract  = {Classic theories of ageing consider extrinsic mortality (EM) a major factor in shaping longevity and ageing, yet most studies of functional ageing focus on species with low EM. This bias may cause overestimation of the influence of senescent declines in performance over condition-dependent mortality on demographic processes across taxa. To simultaneously investigate the roles of functional senescence (FS) and intrinsic, extrinsic and condition-dependent mortality in a species with a high predation risk in nature, we compared age trajectories of body mass (BM) in wild and captive grey mouse lemurs (Microcebus murinus) using longitudinal data (853 individuals followed through adulthood). We found evidence of non-random mortality in both settings. In captivity, the oldest animals showed senescence in their ability to regain lost BM, whereas no evidence of FS was found in the wild. Overall, captive animals lived longer, but a reversed sex bias in lifespan was observed between wild and captive populations. We suggest that even moderately condition-dependent EM may lead to negligible FS in the wild. While high EM may act to reduce the average lifespan, this evolutionary process may be counteracted by the increased fitness of the long-lived, high-quality individuals.},
  language  = {en}
}
@article{HamalainenDammhahnAujardetal.2015,
  author    = {Hamalainen, Anni and Dammhahn, Melanie and Aujard, Fabienne and Kraus, Cornelia},
  title     = {Losing grip: Senescent decline in physical strength in a small-bodied primate in captivity and in the wild},
  series = {Experimental gerontology},
  volume    = {61},
  journal   = {Experimental gerontology},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0531-5565},
  doi       = {10.1016/j.exger.2014.11.017},
  pages     = {54 -- 61},
  year      = {2015},
  abstract  = {Muscle strength reflects physical functioning, declines at old age and predicts health and survival in humans and laboratory animals. Age-associated muscle deterioration causes loss of strength and may impair fitness of wild animals. However, the effects of age and life-history characteristics on muscle strength in wild animals are unknown. We investigated environment-and sex-specific patterns of physical functioning by measuring grip strength in wild and captive gray mouse lemurs. We expected more pronounced strength senescence in captivity due to condition-dependent, extrinsic mortality found in nature. Males were predicted to be stronger but potentially experience more severe senescence than females as predicted by life history theory. We found similar senescent declines in captive males and females as well as wild females, whereas wild males showed little decline, presumably due to their early mortality. Captive animals were generally weaker and showed earlier declines than wild animals. Unexpectedly, females tended to be stronger than males, especially in the reproductive season. Universal intrinsic mechanisms (e. g. sarcopenia) likely cause the similar patterns of strength loss across settings. The female advantage in muscle strength merits further study; it may follow higher reproductive investment by males, or be an adaptation associated with female social dominance.},
  language  = {en}
}