Conduct this AP Biology Lab. Record your data/calculations. In this experiment you will observe the effects that genetic drift can have on the allele frequency in a populationover time.
1. A population of glacier chipmunks lives in an alpine meadow at the base of a steep mountain. A single genedetermines the number of stripes on their face. The black beans represent the two-stripe allele and the whitebeans represent the three-stripe allele. In this species of glacier chipmunk, the two-stripe allele is dominant tothe three-stripe allele.
2. Set up your initial population by placing 50 black beans and 50 white beans in a bowl. Record these numbersas a percentage of the total population in decimal form in the parent population allele frequency column.
3. Calculate the predicted genotype frequency using the Hardy-Weinberg equation p2+ 2pq + q2= 1. Rememberthat pis the frequency of the dominant allele in the population and q is the frequency of the recessive allele inthe population. Also remember that p2represents the homozygous dominant trait, 2pq represents theheterozygous trait, and q2represents the homozygous recessive trait.
4. Reproduction will be carried out by randomly selecting (without looking) two beans out of the bowl. Create atally mark on a piece of paper for each corresponding observed genotype (two black beans = AA, a black anda white bean = Aa, two white beans = aa) to maintain the same proportions of each gene and simulate alarger population size.
5. Add the following information to the scenario: The population of glacier chipmunks is decimated on an annualbasis by avalanches coming off the steep mountain slope. In year 1, only 20 individuals survive. RepeatStep 4 until you have drawn out 20 individuals. Record the observed number for each surviving offspringgenotype. Calculate the observed genotype frequency by dividing the observed number of homozygousdominant individuals by the total number of surviving individuals. Repeat this calculation for the heterozygousand homozygous recessive genotypes.
6. Calculate the observed allele frequency is calculated by finding the total number of each allele present in thepopulation and dividing it by the total number of alleles in the population. Because each homozygousindividual has two of the same allele, you need to multiply the number of homozygous individuals by 2 andadd the number of heterozygous individuals to find the total number of each allele. The total number of allelesin the population is the number of individuals multiplied by 2.Based on this principle, use the followingformulas to calculate the observed allele frequency for A (p) and a (q):
P = [ 2(# of AA) + (# of Aa) ] / 100 q = [ 2(# of aa) + (# of Aa) ] / 100
7. Use the observed allele frequency in this generation as the parent population allele frequency for the nextgeneration. Adjust the number of black and white beans in the bowl to correspond with the parent populationfor the next generation by multiplying the parent population allele frequency by 100 (the number of alleles inthe population)
8. Repeat Steps 3-7 for four generations. For Generation 2, select 30 offspring; Generation 3, 10 offspring; andGeneration 4, 20 offspring.
**Your date should include parent population allele frequency (A, a), Predicted genotype number / frequency (AA, Aa, aa), Number of Surviving offspring, Observed genotype number / frequency (AA, Aa, aa), as well as Observed allele frequency (A, a)** Create a table.
Lastly, answer these 2 questions.
1) Describe how genetic drift changed the genotype frequency of your population. How does genetic drift differ from natural selection?
6) Is genetic drift likely to act faster on large populations or small populations? Explain.