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BIOC51H3 Lecture Notes - Telomere, Life History Theory

Biological Sciences
Course Code
Maydianne Andrade

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BGYB51H3 Lecture 22-23 Notes
-life history theory explains variation
x sexual maturity
x offspring size
x number of offspring
x number of reproductive bouts
x longevity
-perfect organism produces large high quality offspring, matures early and lives forever
-life history theory explains that there are trade offs in organisms due to biological processes
taking some time, finite energy, and limited resources
-natural selection favours balance of allocation to maximize reproductive success and
resources through balancing time and energy
-variation in life histories comes from variation in resource allocation strategies used by
-increased size at sexual maturity can lead to increased reproductive output with the cost of
possibly being killed by predators as well as decreased repair
-mutations that cause later maturity can be beneficial except in high predation areas
-early sexual maturity under intense predation pressure is more beneficial than later maturity
-extrinsic factors can affect the reproductive success of organisms with different maturity times
-allocation strategies are shaped by natural selection over time to favour certain traits
-aging is the extent to which one declines in function physiologically (varies across organisms)
-some organisms have little to no senescence but die eventually
-rate of living hypothesis is a mechanistic hypothesis about senescence while evolutionary
hypothesis explains the variation in aging
-rate of living hypothesis is aging is caused by the accumulation of tissue/cell damage through
errors in DNA, degradation of telomeres in DNA as well as metabolic by-products
-rate of living hypothesis proposes that natural selection has no effect on life-span because
-rate of living hypothesis also proposes that animals with higher metabolic rates will have
higher rates of aging (not supported because of mammal example)
-support for this hypothesis comes from the fact that the senescence rate is correlated with the
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