BIOL488 Lecture : Chap 20.doc
7 Feb 2013
School
Department
Course
Professor
Document Summary
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. Again there is a trade-off: allocating less energy to reproduction means having smaller litters (babies) Why do organisms age and die: 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: two theories on why aging persists, therefore aging should be opposed by natural selection, rate-of-living theory. Posits that populations lack the genetic variation to respond any further to selection against aging: evolutionary theory. Invokes a trade-off between the allocation of energy to reproduction versus repair. And yet, longer life spans have not evolved.
