A dog breed has genotype frequencies as follows:

$f(CC)=0.01 \quad f(Cc)=0.18 \quad f(cc)=0.81$



Assuming the size of the population is 110, how many dogs with each genotype would you expect the population to have?



Dogs with genotype CC = □

Dogs with genotype Cc = □

Dogs with genotype cc = □

Verified Answer :

  • Identify the population size \(N = 110\) and the given frequencies for the three genotypes.
  • Apply the formula for expected frequency: \(N_{genotype} = N \times f(genotype)\).
  • Multiply the total population by each genotype frequency to find the counts for \(CC\), \(Cc\), and \(cc\).
  • Verify the total count sums to 110.
  • The expected counts are: \(CC = \boxed{1.1}\), \(Cc = \boxed{19.8}\), and \(cc = \boxed{89.1}\).

Explanation

  1. Analysis of the Population and Frequencies

The population consists of \(N = 110\) dogs, with the following genotype frequencies: \(f(CC) = 0.01\), \(f(Cc) = 0.18\), and \(f(cc) = 0.81\). The total sum of frequencies is \(0.01 + 0.18 + 0.81 = 1.00\), which confirms that these frequencies represent the entire population. Our objective is to determine the expected number of dogs for each of these three genotypes.

  1. Methodology for Calculating Expected Numbers

To find the expected number of individuals with a specific genotype in a population, we multiply the total number of individuals by the frequency of that genotype. Specifically:

  • The expected number of dogs with genotype \(CC\) is \(N_{CC} = N \times f(CC) = 110 \times 0.01\).
  • The expected number of dogs with genotype \(Cc\) is \(N_{Cc} = N \times f(Cc) = 110 \times 0.18\).
  • The expected number of dogs with genotype \(cc\) is \(N_{cc} = N \times f(cc) = 110 \times 0.81\).
  1. Calculation and Verification

Performing the multiplications:

  • For \(CC\): \(110 \times 0.01 = 1.1\).
  • For \(Cc\): \(110 \times 0.18 = 19.8\).
  • For \(cc\): \(110 \times 0.81 = 89.1\).

To verify the accuracy of these calculations, we sum the expected counts: \(1.1 + 19.8 + 89.1 = 110.0\). The sum matches the original population size of 110, confirming our calculations are correct.

  1. Final Results

Based on the calculations above, the expected number of dogs for each genotype in a population of 110 is:

  • Dogs with genotype \(CC\) = \(\boxed{1.1}\)
  • Dogs with genotype \(Cc\) = \(\boxed{19.8}\)
  • Dogs with genotype \(cc\) = \(\boxed{89.1}\)

Examples

Understanding expected frequencies is fundamental in population genetics, as it helps researchers predict the prevalence of specific traits or genetic diseases within a group. For example, if a specific genotype is associated with a manageable health condition, a breeder can estimate how many puppies in a litter or an entire population might require special veterinary care. This predictive modeling allows for better resource management and responsible breeding practices.