Download Evolution Problem Set II Coat color in the red fox is controlled by

Evolution Problem Set II
Coat color in the red fox is controlled by three major genes, AGOUTI (A, a), BLACK
(B,b), and EXTENSION (E, e), each with two alleles. The AGOUTI gene produces
either a phaeomelanin (A-; red) or eumelanin (aa; black). The BLACK gene determines
the deepness of the black color either a deep black (B-) or a more chocolate color (bb),
and lastly the EXTENSION gene produces a silver banding pattern (E-) in eumelanistic
foxes. A mating study found the following mutation rates
Aa = 44.5*10-6,
Bb = 3.3*10-6,
Ee = 16.4*10-6,
aA = 4.2*10-6,
bB = 1.2*10-6,
eE = 13.9*10-6.
Cross-phase red fox
Red-phase red fox
Black-phase red fox
Silver-phase red fox
These coat colors than can produce the following coat colors
Red
AABB-Smoky red AABb--
Alaska cross AaBB-Blended cross AaBb--
Standard black AAbbee
Alaska black
aaBBee
Sub-Alaska black aaBbee
Substand. black Aabbee
Double silver
aabbEStand. Silver
AAbbESubstand. Silver AabbEAlaska silver
aaBBESubAlaska silver aaBbEDouble silver
aabbE-
Stand. = Standard; Substand. = Substandard
The coat colors look as described, red-phase is what you think of when picturing a red
fox, entirely covered with red fur (phaeomelanin pigment), black foxes are all black
(eumelanin pigment), and silver foxes are a silvery-gray (eumelanin banded with white).
The different states (Alaska, Blended, double, etc) reflect the intensity of the coloration.
The cross-phase have the majority of the coats express phaeomelanin, while a line of
eumelanistic fur runs down the spine and across the shoulders producing a cross.
1. What is the frequency you would expect for each allele at each locus, once the
population reaches equilibrium, with mutation as the only evolutionary pressure?
2. When you sample a population of fox in northern Ontario you find that that 44%
of the population expresses the double-black phenotype. Because the mutation
rate from Aa is so much greater than the mutation rate of aA, Bb, and
bB, assume that these mutation rates are effectively zero. What will be the
frequency of the double-black fox in 150 years?
3. In southern Ontario, the frequency of the double-black phenotype is 18%. The
population size of red fox in southern Ontario is much much larger than the
population size of red fox in northern Ontario. Assuming a migration rate of 7%,
what will be the frequency of the double-black phase in southern Ontario and
northern Ontario in 30 years?
4. The red fox population exists as four populations, across eastern Canada. Given
the following migration rates, what will be the frequencies of the A allele in each
population in 5 years? Assume no mutation occurs.
Populations
Migration rate
Population
Freq of Red-phase
Pop 1  Pop 2 = 0.1
Population1
0.38
Pop 1  Pop 3 = 0.05
Population2
0.49
Pop 1  Pop 4 = 0.001
Population3
0.62
Pop 2  Pop 3 = 0.1
Population4
0.11
Pop 2  Pop 4 = 0.03
Pop 3  Pop 4 = 0.08
Pop 4
Pop 1
Pop 3
Pop 2
5. The color-phase of the red fox is suggested to be related to latitude, such that the
black-phase foxes are more common in the north than the south. One suggestion
is that the dark-coloration is more difficult for prey to notice during the summer
months. In population 4, during 2006, you find the following average litter sizes
for the three major phenotypes (Red, Cross, Black): red-phase = 2.7, cross-phase
= 3.0, black-phase = 3.3, and 11% of the fox population exhibits the red-phase
phenotype. Given the mutation rates at the beginning of the problem, what will
be the frequency of the a allele in population 4 in 2011?
6. To try out the equation you should be working on, given the migration rates in
question 4, and the rest of the data from question 5, what will be the allele
frequency in population 4 in the presence of selection, mutation, and migration in
2007? THIS PROBLEM WON’T BE ANSWERED ON THE KEY OR BY ME.