Question

Researchers studying rock pocket mice across a 35 kilometer transect in the Arizona Sonoran Desert trapped a total of 225 mice and recorded substrate color and coat-color frequencies for each location. Each site was separated from any of the others by at least eight kilometers. Their data are summarized below.

Collecting site Substrate color Number light phenotype Dark phenotype
1 Light 6 6 6
2 light 85 80 5
3 Dark 7 0 7
4 Dark 5 0 5
5 Dark 45 3 42
6 Light 77 34 43

Calculate the overall frequencies of dark-colored mice and light-colored mice caught on dark-colored substrates.

Answer 1

• Frequency of light colored mice caught on dark-colored substrate =

1. Allele frequency = 0.013
2. Genotypic frequency = 0.000169

• Frequency of dark colored mice caught on dark-colored substrate =

1. Allele frequency = 0.24
2. Genotypic frequency = 0.0576

Genotypic frequency of Dd = 0.00624

Step-by-step explanation:

Frequency = no. of mice of one color / total no. of mice

• Light colored mice frequency on dark substrate = 3/225

= 0.013 (d)

• Dark colored mice frequency on dark substrate = (7+5+42)/225

= 54/225

= 0.24 (D)

These are allele frequencies.

Genotypic frequency = p²+q²+2pq

where, p= homozygous dominant q= homozygous recessive and pq= heterozygous

Genotypic frequency of dd = q²

= (0.013)²

= 0.000169

Genotypic frequency of DD = p²

= (0.24)²

= 0.0576

Genotypic frequency of Dd = 2pq

= 2 × 0.24 × 0.013

= 0.00624