BIOC51H3 Lecture : Readings 15 notes
11 Aug 2010
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Readings 15
Pgs. 483-502 (refer to pg485 and 489)
-life history analysis is the branch of evolutionary biology that attempts to make sense of the
diversity in reproductive strategies
-the amount of energy an organism can harvest is finite and biological processes take time
according to the laws of physics and biology
-the benefit of being large is balanced by the cost of being susceptible to predators
-an individual that takes time to growth risks dying without reproducing at all
-whenever there is a trade off between different components of fitness, natural selection
favours the individuals that allocate energy and time with an optimal balance between benefits
and costs
-environmental variation is undoubtedly the source of much of the life history variation seen
among living organisms
-differences among life histories concern differences in allocation of energy
-allocating energy to different areas such as reproduction, metabolism, and repair all have
trade offs
-allocating energy to repair keeps tissues in better condition with the risk of having fewer
offspring
-allocating energy away from growth also produces fewer offspring
-aging, or senescenceU]oo](o]v]vv]v]À]µo[(]o]Çv}]o]Ç}(µÀ]Ào
-there are two theories of why aging exists
x Rate of living theory says that populations lack the genetic variation to respond to any
further to selection against aging
x The Evolution Theory says that aging is a trade off between the allocation of energy to
reproduction versus repair
RATE OF LIVING THEORY
-rate of living theory of senescence holds that aging is caused by the accumulation of
irreparable damage to cells and tissues, caused by errors during various DNA processes
-this theory makes two predictions
x Because of cell/tissue damage due to metabolism, aging rate is correlated with
metabolic rate
x Because organisms have been selected to resist and repair damage to maximum
extent possible, species are not able to evolve longer life spans
-the rate of living theory persists due to the fact that some cellular and genetic mechanisms
have appeared to link the senescence of cells to the senescence of organisms
-telomeres of a cell consist of repetitive DNA sequences that are lost for every cycle of DNA
replication, linking them to senescence and death of the cell
-after much experimentation, there is no simple relationship between telomere length, the
replicative senescence of cells and whole organism aging and death
www.notesolution.com
Document Summary
Life history analysis is the branch of evolutionary biology that attempts to make sense of the diversity in reproductive strategies. The amount of energy an organism can harvest is finite and biological processes take time according to the laws of physics and biology. The benefit of being large is balanced by the cost of being susceptible to predators. An individual that takes time to growth risks dying without reproducing at all. Whenever there is a trade off between different components of fitness, natural selection favours the individuals that allocate energy and time with an optimal balance between benefits and costs. Environmental variation is undoubtedly the source of much of the life history variation seen among living organisms. Differences among life histories concern differences in allocation of energy. Allocating energy to different areas such as reproduction, metabolism, and repair all have trade offs. Allocating energy to repair keeps tissues in better condition with the risk of having fewer offspring.
