Evolution of Aging
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Transcript of Evolution of Aging
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Evolution of Aging
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I. Evidence for senescence and evidence for the evolution of senescence
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Artificial selection increases life span in fruit fliesInherent limits, or can lifespan evolve?Fruit fly expt:
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Female sockeye salmon defending its nest before dying
II. Fundamental Trade-offs
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Mite Kiwi bird
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Short-winged and long-winged morphs of female sand crickets (Gryllus firmus)
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The life history of a hypothetical female Virginia opossum (Didelphis virginiana)
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III. Evolutionary theories of aging Background:
Expected Reproductive Success (RS) = Prob(Surviving) x #(Offspring)
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Versus 2.419
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Versus 2.419
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Two Theories
A. 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
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A. Mutation Accumulation Hypothesis (drift, non selection)
Mutations expressed later in life, near the end of reproduction are effectively neutral
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B. Antagonistic Pleiotropy Hypothesis
The longevity allele hx546 under (a) benign and (b) stressful conditions
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Trade offs in fruit flies between longevity and reproduction
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Collared flycatchers: (a) natural variation and (b) experimental manipulations
Extra eggs
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Differences in mortality Differences maternal ability
Physiological deterioration
Mainland Georgia versus Island populations
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IV. Evolution of Senescence and Human Reproduction
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Functional capacity of various physiological systems in women as a function of age from Ache hunger-gathers of Paraguay
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Menopause an artifact of living longer?? Probably NOT
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Hazda Woman (hunter-gatherer from East Africa)
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ConclusionAll organisms dieThe timing of reproduction and death can evolveTwo evolutionary theories of senescence: Mutation Accumulation & Antagonistic PleiotropyHuman Menopause may be explained by inclusive
fitness