23.4 Genetic Drift

23.4 Genetic Drift

  • Explain the effects of genetic drift over time.
  • The founder effects are compared and contrasted.
  • Genetic drift can lead to widespread genetic changes in a population.
    • Let's look at the second important way the gene pool of a popu is in a population.
    • The number of lation can change.
  • The blue line shows a population in which N is 1,000, while the red line shows a population in which N is 10.
  • 10 is fixed.
  • Chapter 23 fluctuated from generation to generation.
    • The populations consisted of only black and white mice.
  • The population begins to drift.
  • When the sample size is large, the relative effect of random chance is much smaller.
    • Even in large populations, genetic drift can lead to allele loss or fixation, but it will take many more generations to occur than it does in small populations.
  • When the size of a population decreases, genetic drift may change frequencies.
    • The founder effect is one of two examples of this phenomenon.
  • The destruction of habitat is caused by a dry spell.
    • The population size is decreased and the dark position may be eliminated by these occurrences.
    • The population has passed through a bottle green state.
  • Some alleles may be over-represented.
  • Changes may happen for two reasons.
    • The original population that was much larger had allele frequencies that were different from those of the surviving population.
    • The popula tion may regain its original size after going through a bottleneck.
  • The new population is likely to have less variation in their genes.
  • The popu phenotypes are left in this example.
  • The dark green vari ety is lost due to a shortage.
  • Due to hunting, the population decreased to 20 to 30 members in the 1890s.
    • The species rebounded in numbers to over 100,000, but its genetic variation was reduced to very low levels.
  • In this example, a population of Frogs establishes a colony in a new location.
    • A few individuals from a large population on a continent may move because of the reduced population size.
    • The founding of an island population can be achieved by reducing the genetic diversity in the island.
  • The reduction in pop efforts of biologists who are trying to save species nearing ulation size is related to the new location.
    • There are two consequences of the founder effect.