Campbell Biology 11th Edition by Lisa Urry,Michael Cain,Steven Wasserman,Peter Minorsky,Jane Reece

Exercise 1

Using the Hardy-Weinberg Equation to Interpret Data and Make Predictions
Is Evolution Occurring in a Soybean Population One way to test whether evolution is occurring in a population is to compare the observed genotype frequencies at a locus with those expected for a nonevolving population based on the Hardy-Weinberg equation. In this exercise, you'll test whether a soybean population is evolving at a locus with two alleles, C G and C Y , that affect chlorophyll production and hence leaf color.
How the Experiment Was Done Students planted soybean seeds and then counted the number of seedlings of each genotype at day 7 and again at day 21. Seedlings of each genotype could be distinguished visually because the C G and C Y alleles show incomplete dominance: C G C G seedlings have green leaves, C G C Y seedlings have green-yellow leaves, and C Y C Y seedlings have yellow leaves.
Calculate the observed frequencies of genotypes C G C G , C G C Y , and C Y C Y at day 7. (The observed frequency of a genotype in a gene pool is the number of individuals with that genotype divided by the total number of individuals.) Compare these frequencies to the expected frequencies calculated in step 2. Is the seedling population in Hardy-Weinberg equilibrium at day 7, or is evolution occurring Explain your reasoning and identify which genotypes, if any, appear to be selected for or against.