Please read carefully the sections below in your PopGen-manualor online:
1. Background Information
4. Before you begin
Answer the following problems: Do several repeats of all experiments to see if the outputs vary by chance, or if it looks stable, after changing different parameters.
Ass. 1: "Getting to know PopGenLab: Testing the Hardy-Weinberg Theorem "
Does each month genotype have an equal chance of survival or is there a selective pressure (positive or negative) on one or more genotypes using default settings? Is there a change in allele and/or genotype frequency over time?
How do the actual genotype frequencies compare to Hardy-Weinberg predictions?
Did the results agree with your predictions (do several experiments to verify)?
Use Chi-square analysis with one degree of freedom to test your prediction.
How many generations does it take for a population to reach Hardy-Weinberg equilibrium?
Can different initial genotype frequencies lead to the same Hardy-Weinberg equilibrium?
Ass. 2: "Genetic Drift" (Here you change the tree stand carrying capacity)
1. Formulate a hypothesis to predict the effect of a decrease in tree stand carrying capacity on allele and genotype frequencies.
2. What happens to allele and genotype frequencies if you change the tree carrying capacity? Do several experiments with several different capacities.
3. What happens to the percentage of heterozygotes? describe these results.
4. What do these experiments tell you about the effect of population size on genetic variation?
5. Did any of the populations that you studied become extinct? If so, which ones? What can you say about the relationships between carrying capacity and the risk of extinction?
Ass. 3: "The influence of mating patterns on population genetics" (here you change the mating pattern (random, assortative, disassortative)). Set the tree stand number to 100.
1. What is the effect of assortative mating on genotype, allele frequencies and heterozygosity?
2. How do the effects of assortative mating compare to those of genetic drift? Are the effects of assortative mating and the effects of genetic drift the same at different population sizes?
3. What is the effect of disassortative mating?
4. How do assortative and dissassortative mating affect allele frequency?
Ass. 4: "Modes of natural selection" (Here you change the color of the trees, more white trees gives natural selection for white moths). Do several experiments with different percentages of tree colors. Set the tree stand number to 100.
1. What happens to allele frequency in the case of directional selection?
2. What happens to allele frequency in the case of balancing selection?
3. What happens to allele frequency in the case of diversifying selection?
4. Are small differences in fitness effective in changing allele frequencies? Under what mode of selection might genetic variation be maintained?