In this first exercise, we are going to look for evidence of evolutionary change

Question

In this first exercise, we are going to look for evidence of evolutionary change in a population in the absence of natural selection by looking at the change in allele frequencies over time in a simulated population. We will start with a population of 50 individuals in which there are two alternate alleles (H and h) in equal proportions (each at a frequency of 0.5 or 50%). Individuals have the possible genotypes: HH, Hh or hh. These two alleles do not offer any selective advantage, so neither is selected for or against, meaning they are neutral. We will record the frequency of these alleles over 10 generations. Prior to advancing on to the next generation, six alleles (= three individuals) will be removed at random.

Before you begin, answer the following:

Question

What is your prediction as to what will happen to the frequencies (note that this is different than the number) of these two alleles over 10 generations? Word your prediction as an

Explanation / Answer

According to Hardy weinberg's law : p + q=1 , where p= allele frequency of dominant allele, H and q= genotype frequency of recessive allele, h.

0.5 + 0.5 = 1

p2 + 2pq +q2 = 1

where , p2= genotype frequency of homozygous dominant, HH = 0.5 * 0.5 = 0.25

2pq = genotype frequency of heterozygous, Hh = 2 * 0.5 * 0.5 = 0.5

q2 = genotype frequency of homozygous recessive , hh = 0.5 * 0.5 = 0.25

This is following mendelian 1:2:1 ratio.

Even if we keep removing individuals at random from the population, these allele frequencies and genotype frequencies will remain same.So, uptil 10 generations all individuals will remain same.

Taking generation on X axis and allele frequency on Y axis a straight horizontal line will be formed

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