Question

Dr. Ndaiye observes a population of skunks for white stripe width phenotype. This characteristic is coded for by two alleles, E, which codes for wider stripes, and e, which codes for thinner stripes. In the population, there are 83 EE individuals, 4 Ee individuals, and 97 ee individuals. Use Hardy-Weinberg to assess if this population is evolving for this characteristic.

a) Hardy-Weinberg provides the genotype frequencies for a population that is NOT evolving based on the allele frequencies of that population. The first step to assessing the evolution of this population is calculating p and q values for this population. Enter these values in the blanks below.
b) Next, use your p and q values from the question above to calculate the EXPECTED genotype frequencies for a population that is NOT evolving.
c) Now, calculate the genotype frequencies observed in the population.
d) is the population likely evolving for white stripe width, not evolving, or most likely evolving because of genetic drift?

Answer 1

The first step is to calculate the p and q values, which represent the allele frequencies. Next, using the p and q values, we can calculate the expected genotype frequencies for a non-evolving population. Then, we compare the expected and observed genotype frequencies to assess if the population is evolving.

Step-by-step explanation:

The first step to assessing if a population is evolving based on the Hardy-Weinberg equation is to calculate the allele frequencies, p and q. Allele frequencies represent the proportion of the population carrying each allele. In this case, p represents the frequency of the E allele, and q represents the frequency of the e allele. To calculate p, divide the number of EE individuals by the total number of individuals in the population. To calculate q, divide the number of ee individuals by the total number of individuals in the population. In this case, p = 83 / (83 + 4 + 97) = 0.45 and q = 97 / (83 + 4 + 97) = 0.53.

The expected genotype frequencies for a population that is not evolving can be calculated using the p and q values. The expected frequency of the EE genotype is p squared (p^2), the expected frequency of the Ee genotype is 2pq, and the expected frequency of the ee genotype is q squared (q^2). In this case, the expected genotype frequencies are EE = (0.45)^2 = 0.2025, Ee = 2 * 0.45 * 0.53 = 0.477, and ee = (0.53)^2 = 0.2809.

The observed genotype frequencies can be calculated by dividing the number of individuals with each genotype by the total number of individuals in the population. In this case, EE = 83 / (83 + 4 + 97) = 0.43, Ee = 4 / (83 + 4 + 97) = 0.02, and ee = 97 / (83 + 4 + 97) = 0.50.

Finally, to assess if the population is evolving, we compare the expected and observed genotype frequencies. If the observed genotype frequencies deviate significantly from the expected frequencies, it suggests that the population is evolving. In this case, the population is most likely evolving because the observed genotype frequencies of Ee and ee deviate from the expected frequencies.