Question

2. In a particular species of salamander the skin can either be black or brown. The black phenotype is recessive to the brown phenotype. Within a population of 1000 salamanders, 640 have the brown phenotype. Calculate the allele frequencies for this population. Show all of your work. How many heterozygotes are there? Make up an environmental change that could occur (not an oil spill or something we’ve talked about, invent your own) that would cause a shift in the allele frequencies. How would your environmental change affect p and q?

Answer 1

Answer:

Black allele = q

Brown allele = p

Black = 1000 – 640 = 360

Frequency of black = q^2 = 360/1000 = 0.36

Frequency of black allele = q = SQRT of 0.36 = 0.6

Frequency of brown allele = p = 1-0.6 = 0.4

No. of heterozygotes = 2*0.4*0.6*1000 = 480

If environment favors black phenotype, the black allele (q) frequency will be increased and brown allele (p) frequency will be decreased.

If environment favors brown phenotype, the black allele (q) frequency will be decreased and brown allele (p) frequency will be increased.