Evolution of Aging

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Evolution of Aging
Katy Nicholson and Coco Shea
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Why do organisms age?
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Definition of Aging (Senescence)

• Decline in individuals fertility and
  probability
• of survival
• Lose ability to completely repair mutations in
• cells and tissue (lack of energy)

• Decline in individuals fertility and
  probability
• of survival

• Decline in individuals fertility and
  probability
• of survival

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Rate of Living Theory

• Populations lack the genetic variation necessary
  to respond to selection against aging

• Populations lack the genetic variation necessary
  to respond to selection against aging

• Telomeres are shortened every time a cell
  divides (Harley et al. 1990)

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Evolutionary Theory of Aging

• Accumulation of deleterious mutations after
  reproductive age

• Accumulation of deleterious mutations after
  reproductive age

• Less selective pressure on deleterious mutations
  after reproductive age

• Neutral alleles can drift to fixation

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Evolution of Shorter Life Span Accumulation of
Deleterious Mutations
Fig. 12.11 Houseflies - Reed and Bryant (2000)
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Energy Trade-Offs

• Reproduce Early or Reproduce Longer?

• Reproduce Early or Reproduce Longer?

• Antagonistic Pleiotropy Hypothesis Mutation
  
• allocates energy to early reproduction or late
  death

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Antagonistic Pleiotropy Hypothesis

• eg. Nematode Caenorhabditis elgans (Walker et
  al. 2000)

• eg. Nematode Caenorhabditis elgans (Walker et
  al. 2000)

Fig. 12.12
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Conclusion

• Aging is accumulation of deleterious
• mutations

• Aging is accumulation of deleterious
• mutations

• Allocate energy to reproducing early or to
• repairing cells later