Tuesday, September 30, 2014

Natural Selection and Adaptation (Cont.)


  • Evolution by natural selection takes place when some individuals survive and reproduce better than others in a particular environment and the heritable characteristics of a population change from one generation to the other due to that.
  • Fitness is measured by the number of descendants left by individuals in a population.
  • Evolution is not perfect: Evolved individuals might have characteristics that are suited to the environments of their ancestors but not so much to their current environments.
  • Fitness is relative: evolved individuals can be the best fit for their current environments but not the perfect fit.
  • Precise matches between an organism and its environment may equally be seen as constraints making such organism dependent on such specific environment.


  1. Does fitness depend on the number of offspring only and why?
  2. What is the ultimate fitness?