Describe how and why the allele frequency of a gene pool is affected by population size and gene flow between populations

allele-frequency
gene-flow

#1

describe how and why the allele frequency of a gene pool is affected by population size (large population vs small population) and gene flow between populations.

Answer:

Population not isolated: 13.11

  • migration into or out of population, called “gene flow”
  • gene flow between populations can shift allele frequencies; increases genetic variation because different populations may have different allele frequencies
  • gene flow between populations maintains genetic similarity of populations - isolation (no gene flow) important in speciation
    Population small : 13.11
  • large population size reduces the effects of chance, small populations effected more by
    chance events
  • “genetic drift” is random change in allele frequencies due to random events (matings, deaths, etc)
  • allele frequencies can change erratically to higher or lower frequency by chance - alleles can be eliminated (0%) or “fixed” (100%)
  • tends to reduce genetic variation within population
    Ex. a population with random deaths ----- and matings <---->
    AA
    AA
    AA Aa aa
    AA1 AA
    Aa aaAA
    First generation
    allele frequency A = 11/16
    A1 = 1/16 a = 4/16
    Next generation A = 8/16
    A1 = 0
    a = 8/16
    AA
    Aa
    Aa Aa aa Aa