Question

Question 2 Part A [5 marks] If a new mutation for lactase persistence arises in a human population of size N = 10, what is the probability that the mutation will spread to fixation under each of the following scenarios? i a population with no culture of dairying, where the mutation is neutral ii a population with a culture of dairying, where the mutation has a selective advantage of s 0.1

Answer 1

I) The population size, N = 10⁵ = 100000

The probability that the mutation will spread to fixation under a population with no culture of dairying where the mutation is neutral , q = 1/2N = 1/2x 100000 = 1/200000 = 5 x 10^-6

The probability that the mutation will spread to fixation under a population with a culture of dairying where the mutation has a selective advantage of s = 0.1,

p = 1- e^-2s/1-e^-4Ns = 1-e^-0.2/1-e^{-4x100000x0.1} = 1-0.819/1-0 = 0.181 $\approx$ 0.2

it can be calculated directly p $\approx$ 2s/1-e^-4Ns$\approx$ 2x0.1/1-0 $\approx$ 0.2