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Decades of field data reveal that turtles senesce in the wild
Proceedings of the National Academy of Sciences
  • Daniel A. Warner, Iowa State University
  • David A. W. Miller, Pennsylvania State University
  • Anne M. Bronikowski, Iowa State University
  • Fredric J. Janzen, Iowa State University
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Accepted Manuscript
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Lifespan and aging rates vary considerably across taxa; thus, understanding the factors that lead to this variation is a primary goal in biology and has ramifications for understanding constraints and flexibility in human aging. Theory predicts that senescence—declining reproduction and increasing mortality with advancing age—evolves when selection against harmful mutations is weaker at old ages relative to young ages or when selection favors pleiotropic alleles with beneficial effects early in life despite late-life costs. However, in many long-lived ectotherms, selection is expected to remain strong at old ages because reproductive output typically increases with age, which may lead to the evolution of slow or even negligible senescence. We show that, contrary to current thinking, both reproduction and survival decline with adult age in the painted turtle, Chrysemys picta, based on data spanning >20 y from a wild population. Older females, despite relatively high reproductive output, produced eggs with reduced hatching success. Additionally, age-specific mark–recapture analyses revealed increasing mortality with advancing adult age. These findings of reproductive and mortality senescence challenge the contention that chelonians do not age and more generally provide evidence of reduced fitness at old ages in nonmammalian species that exhibit long chronological lifespans.


This is a manuscript of an article from Proceedings of the National Academy of Sciences 113 (2016): 6502, doi: 10.1073/pnas.1600035113. Posted with permission.

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Warner et al.
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Daniel A. Warner, David A. W. Miller, Anne M. Bronikowski and Fredric J. Janzen. "Decades of field data reveal that turtles senesce in the wild" Proceedings of the National Academy of Sciences Vol. 113 Iss. 23 (2016) p. 6502 - 6507
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