Question

In a population of 1000 wild dogs in a grassland, 360 and 480 dogs had black body colour with genotypes BB and Bb, respectively. In the same population, remaining dogs were white in colour with a genotype of bb. Based on this data, the frequency of allele “b” in the population is _______ (round off to one decimal place).

Hint:

To calculate allele frequency: \(\text{freq}(b) = \dfrac{2N_{bb} + N_{Bb}}{2N_{\text{total}}}\).

Answer 1

Step 1: Genotype counts. Total population = 1000. BB = 360, Bb = 480, bb = 160 (since 1000 – 360 – 480 = 160). Step 2: Total alleles. Each dog carries 2 alleles \(⇒\) total alleles in population = \(1000 \times 2 = 2000\). Step 3: Count of “b” alleles. From BB: 0 “b” alleles. From Bb: each has 1 “b” allele \(⇒ 480 \times 1 = 480\). From bb: each has 2 “b” alleles \(⇒ 160 \times 2 = 320\). Total “b” alleles = \(480 + 320 = 800\). Step 4: Allele frequency. Frequency of “b” = \(\dfrac{800}{2000} = 0.4\).