Week%205%20Lab%20Problem%20Solving%20-%20Hardy%20Weinberg%20W24%20+%20CURE%20-%2

Week 5 Lab Problem Solving – Testing Hardy-Weinberg Equilibrium Learning Objectives ● Define the Hardy-Weinberg Equilibrium. ● Calculate allele frequencies based on phenotypic or genotypic data for a population. ● Calculate genotype frequencies expected under HW equilibrium in a population given its allele frequencies. ● Recognize the importance of HW equilibrium as a null hypothesis. ● State whether a population is evolving based on deviations from HW equilibrium. This activity will be completed and submitted as a group. Each member of your group must lead the discussion for at least one problem. Before you begin , determine how you will distribute responsibilities amongst your group members evenly. 1. With your lab group, discuss the significance of Hardy-Weinberg Equilibrium using the terms null hypothesis, allele frequency, expected genotype, and observed genotype. Then, confirm with a neighboring group, LA, or TA before summarizing your groups discussion here. A population in Hardy-Weinberg equilibrium will exhibit genotype frequencies that stay the same from one generation to the next, and their respective dominant and recessive ratios will always add up to 1. The allele frequencies are in terms of p and q, p being the dominant allele, and q being the recessive allele. P^2+2PQ+Q^2 is the equation that should add up to 1 if a population is in HWE. The null hypothesis would state that there is no difference between expected genotype and observed genotype frequencies if a population is in HWE, and that evolution is not occurring. If the null hypothesis can be rejected, then evolution is occurring and observed genotype frequencies differ from the expected values–they would not satisfy the p^2+2pq+q^2=1 equation. [Questions 2-5] Koi fish color is determined by two co-dominant alleles ( R1 and R2 ): homozygous R1 individuals have a solid white scale color, homozygous R2 individuals - a solid orange scale color, and heterozygous individuals ( R1R2 ) - a white scale color with orange spots. Your city has decided to create a canal that connects multiple previously isolated Koi ponds in your city’s botanical garden. You survey a population of isolated Koi fish in one of their ponds before the canal is built and then survey the same pond after the canal is built to determine the effect of migration on allele frequency. Use the information above and your survey data to answer the following questions. Show your calculations when applicable. Population Size Frequency of R1R1 Genotype Frequency of R1R2 Genotype Frequency of R2R2 Genotype Initial Survey (Before canal project) 194 0.27 0.4 0.33 Migration Survey (After canal project) 203 0.70 0.25 0.05 2. When looking at only the initial survey data, is there evidence the population is evolving for the scale color gene? There is evidence that the population is evolving for the scale color gene since the observed and expected genotype frequencies in the initial population are different.

Looking at the initial population, we can derive the allele frequencies, which were found to be R1 = 0.47 and R2 = 0.53. With this, we can use the HWE equation of p^2+2pq+q^2=1 to see if the observed and expected genotype frequencies will be the same. To check the frequency of R1R1 individuals, we plug 0.47 into p^2 and get 0.2209; this is our expected genotype, which is different from the observed phenotype of 0.27. Calculating 2(0.47)(0.53) for the frequency of R1R2 individuals yields 0.4982, which is different from the expected value of 0.4. Finally, plugging 0.53 into q^2 gives us 0.2802, which is different from the expected value of 0.33 for R2R2 individuals. Since observed genotype frequencies are different from observed genotype frequencies, this means the initial population is not in HWE, and that there is evolution for this scale color gene.

Week 5 Research Project: Species Comparisons Between Island and Mainland Populations Learning Pod group members: Jake, Nick, Elizabeth, Nadia 1. Provide your hypothesis and null hypothesis: Hypothesis: Channel Island skunks will be larger than their mainland cousins because they have larger access to land and therefore resources. Null Hypothesis: Environment does not have an effect on the variation of size between mainland and island skunks. 2. Which species will you be working on for the project? Channel Island Spotted Skunk (Spilogale gracilis) Find a few photos and paste them here (please size them accordingly)

3. List a minimum of four references (from journals) about your species Genetic differentiation of island spotted skunks, Spilogale gracilis amphiala Sudden increase in a rare endemic carnivore: ecology of the island spotted skunk Genetic variation in the eastern spotted skunk (Spilogale putorius) with emphasis on the plains spotted skunk (S. p. interrupta) Spatial and Genetic Organization of the Island Spotted Skunk, Spilogale gracilis amphiala