Plan to spend 40 minutes on Drift

  1. Take drift quiz
  2. 50 rats from a large outbred population living aboard of large cruise boat areleft on a Pacific island for some reason. The island resources allow only 100 adult rat survive (population will not grow). Ten mutations are present in single copy each in these 50 rats. After very long time...
    1. What is probability that at least one of these mutations will be fixed (reach frequency of 1.0)?
      P(>=1 fixed)=1 - P(0 fixed) = 1 - (99/100)^10 = 0.096
    2. What is probability that two or more of these mutations will be fixed?
      P(>=2 fixed) = 1 - P(0fixed) - P(1fixed)
      P(>=2) = 1 - (99/100)^10 - 10 1/100 (99/100)^9
      P(>=2 fixed) = 0.004 (0.4%)

    3. What is chance that none of these mutations will be fixed?
      P(0 fixed) = (99/100)^10 = 0.904
    4. What will be average time before these mutations are fixed?
      Apply formola frmm handouts
      -4n(1-p)ln(1-p)/p
      -200 99/100 ln(99/100)/(1/100)=199 generations