genetic diversity

• founder effect-

  • This applies when any group of individuals are isolated from a larger breeding population
  • The alleles found in a small group will inevitably be more limited than in a larger group so there is a loss of genetic variation. E.g. I do not have the allele for red hair or blue eyes.
  • Because there is a limited number of individuals this means any alleles possessed by them will inevitably become amplified in subsequent generations
• genetic drift -

  • Normally occurs in small populations (e.g. after a genetic bottleneck or founder event) where infrequently occurring alleles face a greater chance of being lost.
  • This is a random process i.e. even though an organism may be well adapted, random chance means it doesn’t pass on its genes and therefore the allelic frequency will decrease. 
• the bottle neck effect is a decrease in genetic variety due to a sudden elimination of part of the population