BMEN 515 Lecture Notes - Dna Mismatch Repair, Selective Breeding, Mutation
26 Feb 2013
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Fig 13. 2 shows how a female opossum got her energy at different stages of her life, and the functions to which she allocated that finite energy supply. Changes in life history are caused by changes in the allocation of energy: for example, a different female opossum might stop allocating energy to growth at an earlier age, thereby reaching sexual maturity more quickly. Again there is a trade-off: allocating less energy to reproduction means having smaller litters (babies) Aging or senescence- is a late-life decline in an individual"s fertility and probability of survivial. Documentation of a bird, a mammal, and an insect, all show declines in both fertility and survival. If everything else remains equal, aging reduces an individual"s fitness: therefore aging should be opposed by natural selection. Two theories on why aging persists: rate-of-living theory. Posits that populations lack the genetic variation to respond any further to selection against aging: evolutionary theory.
