BIOC51H3 Lecture Notes - Telomere, Life History Theory
11 Aug 2010
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BGYB51H3 Lecture 22-23 Notes
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-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
organisms
-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
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-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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Document Summary
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 organisms. 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)
