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Evolution of Aging

This comprehensive exploration delves into the evolution of aging, highlighting key theories such as Mutation Accumulation and Antagonistic Pleiotropy. By examining artificial selection in fruit flies and trade-offs in various species like sockeye salmon and sand crickets, the study emphasizes the role of senescence in evolution. The potential explanations for human menopause and the functional capacity of physiological systems with age are also discussed. This work aims to illuminate how reproductive timing and lifespan are influenced by evolutionary pressures.

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Evolution of Aging

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  1. Evolution of Aging

  2. I. Evidence for senescence and evidence for the evolution of senescence

  3. Artificial selection increases life span in fruit flies Inherent limits, or can lifespan evolve? Fruit fly expt:

  4. II. Fundamental Trade-offs Female sockeye salmon defending its nest before dying

  5. Mite Kiwi bird

  6. Short-winged and long-winged morphs of female sand crickets (Gryllusfirmus)

  7. The life history of a hypothetical female Virginia opossum (Didelphis virginiana)

  8. III. Evolutionary theories of aging Background: Expected Reproductive Success (RS) = Prob(Surviving) x #(Offspring)

  9. Versus 2.419

  10. Versus 2.419

  11. Two Theories • Senescence reflects relaxed selection (drift) • increased expression of deleterious recessive alleles • increased genetic variation later in life • B. Senescence reflects tradeoffs • loci involved in senescence have early fitness effects • balancing selection signature

  12. Mutation Accumulation Hypothesis (drift, non selection) • Mutations expressed later in life, near the end of reproduction • are effectively neutral

  13. B. Antagonistic Pleiotropy Hypothesis The longevity allele hx546 under (a) benign and (b) stressful conditions

  14. Trade offs in fruit flies between longevity and reproduction

  15. Collared flycatchers: (a) natural variation and (b) experimental manipulations Extra eggs

  16. Mainland Georgia versus Island populations Differences in mortality Differences maternal ability Physiological deterioration

  17. IV. Evolution of Senescence and Human Reproduction

  18. Functional capacity of various physiological systems in women as a function of age from Ache hunger-gathers of Paraguay

  19. Menopause an artifact of living longer?? Probably NOT

  20. Hazda Woman (hunter-gatherer from East Africa)

  21. Conclusion All organisms die The timing of reproduction and death can evolve Two evolutionary theories of senescence: Mutation Accumulation & Antagonistic Pleiotropy Human Menopause may be explained by inclusive fitness

  22. Adult house flies only allowed to live 4 days

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