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Evolution of Aging

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Evolution of Aging & Late Life Chapter 18 Evolutionary Definition of Aging Sustained age-specific decline of fitness related characteristics not due to external ... – PowerPoint PPT presentation

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Title: Evolution of Aging


1
Evolution of Aging Late Life
  • Chapter 18

2
Evolutionary Definition of Aging
  • Sustained age-specific decline of fitness related
    characteristics not due to external environmental
    factors
  • Not possible to study in vast majority of species
    in wild
  • Based on Hamiltons Mathematical Forces of
    Natural Selection.

3
Population Genetic Hypothesis for Aging
  • Antagonistic Pleiotropy
  • Evolutionary Trade-off, alleles with early
    benefit produce bad side effects later
  • Mutation Accumulation
  • Decline of force of natural selection fails to
    remove deleterious mutations

4
Role of Experimental Evolution in Aging
  • If Aging has evolutionary basis-
  • 1.) Early reproduction will accelerate aging in
    population.
  • 2.) Late reproduction will slow aging in
    population.

5
Results
  • Some experimental results consistent with
    Antagonistic Pleiotropy mechanism for evolution
    of aging
  • Other experiments support conclusion that
    Mutation Accumulation contributes to aging in
    Drosophila
  • Aging easily identifiable product of evolution
    involving many genes

6
Discovery of Late Life
  • Studies of populations revealed that mortality
    rates increased exponentially during mid-life,
    plateau later.
  • Two theories-
  • 1) Natural selection drops to zero after
    reproduction has ended
  • 2) Lifelong heterogeneity differences in
    robustness of individuals

7
Results
  • Late-life plateaus change with changes in end of
    reproductive age.
  • 1) Antagonistic Pleiotropy possible
    genetic mechanism
  • No indication lifelong heterogeneity factor in
    Late-life plateaus
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