Investigation #2 Student Sheet
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Investigation #2 Mathematical Modeling: Hardy-Weinberg (Population genetics simulation program by Bob Sheely. Data sheet by Allison Winward.) Go to the simulation model at http://www.radford.edu/~rsheehy/Gen_flash/popgen/ or use the link provided on the class website. For each scenario, write down what you think will happen to the allele frequencies over time. Then enter the given information into the computer model and record the results. Scenario 1: Simulate a population of randomly mating individuals, with no migration or mutation, and equal fitness. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 1-1-1 Data: allele frequency of A1 Start_0.5_ allele frequency of A2 Start_0.5___ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start_0.25__ Start_0.50__ Start_0.25_ End_______ End_______ End_______ Scenario2: In this case you will modify the simulation to make it more realistic. In the natural environment, not all genotypes have the same rate of survival; that is, the environment might favor some genotypes while selecting against others. An example is sickle cell anemia. It is a disease caused by a mutation on one allele, and homozygous recessives often die early in life. For this simulation, you will assume that the homozygous recessive individuals (A2A2) never survive and that heterozygous and homozygous dominant individuals have normal, high survival. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 1-1-0 Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Scenario 3: In the real world, heterozygotes for sickle cell have an advantage over homozygous dominant organisms in the form of resistance to malaria, also a lethal disease in many parts of the world. In this scenario, fitness of A1A1 individuals will be reduced, since they have little malaria resistance. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 0.5-10 Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Scenario 4: Now migration will occur with 25% of the population, in which there is equal fitness. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 1-1-1, click Migration once, rate = 0.25 Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Scenario 5: There will be a high mutation rate of allele A1 changing to allele A2. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 1-1-1, unclick Migration twice, set Mutation rate of A1 A2 = 0.0005 Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ End_______ End_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 Start______ Start______ Start______ End_______ End_______ End_______ Scenario 6: At generation 5, the population will suddenly decrease by half. This bottleneck will end at generation 15, then the population will recover. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Pop size = 50, initial frequency of allele = 0.5, # of populations = 1, # of generations = 25, fitness = 1-1-1, click Bottleneck 5-15-25 Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Set up two other scenarios, define the parameters of the model, predict, then report findings. Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Hypothesis:____________________________________________________________________________________ _____________________________________________________________________________________________ Enter: Data: allele frequency of A1 Start_______ allele frequency of A2 Start_______ genotype frequency A1A1 genotype frequency A1A2 genotype frequency A2A2 End_______ End_______ Start______ Start______ Start______ End_______ End_______ End_______ Discuss which scenario population(s) followed Hardy-Weinberg equilibrium and explain why. Discuss which scenario population(s) did not follow Hardy-Weinberg equilibrium and explain why (what factors caused it to deviate). _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________
