Evolution – Biology 4250                        Hardy-Weinberg Problems                       Spring 2020

SHOW ALL YOUR WORK ! ! ! Round answers to the nearest two significant digits past the
decimal point.  Unless otherwise specified, assume populations are in a (fictitious) H-W equilibrium.
(34 pts.)

1. In a population with 2 alleles for a particular locus (D and d), the frequency of the d allele is 0.55.
         (4 pts.)
a) What is the frequency of the D allele?

b) What is the frequency of homozygous recessive individuals in the population?

c) What is the frequency of homozygous dominant individuals in the population?

d) What is the frequency of heterozygotes in the population?


2. The fraggles are a population of mythical, mouselike creatures that live in underground tunnels and
chambers beneath a large vegetable garden that supplies their food. They can reproduce VERY
quickly! Of the fraggles currently in this population, 372 have green fur and 182 have gray fur. Green
fur is controlled by a dominant allele F and gray fur by a recessive allele f. (5 pts.)

a) What is the frequency of the gray allele f?

b) What is the frequency of the green allele F?

c) How many fraggles are heterozygous (Ff)?

d) How many fraggles are homozygous recessive (ff)?

e) How many fraggles are homozygous dominant (FF)?

3. In a population that is in Hardy-Weinberg equilibrium, 37% of the individuals exhibit the recessive
trait (ss). (2 pts.)

a) What is the frequency of the dominant allele (S) in the population?

b) What percent of the population possesses the dominant allele (S)?


4. In a large, randomly mating population with no appreciable forces working to change gene frequen-
cies, the frequency of homozygous recessive individuals for the characteristic of extra-long eyelashes is
60 per 1000. What percent of this population carries this very desirable trait but displays the dominant
phenotype of short eyelashes? (2 pts.)



5. Coat color in sheep is determined by a single gene. Allele B, for white wool, is dominant over allele
b, for black wool. We have followed a population of sheep for two years. Below are the statistics we
have compiled. (8 pts.)
                                            Year 1         Year 2

White sheep                             1567         1723

Black sheep                               429           496

Total number of individuals       1996         2219

a) Determine the frequency of both alleles (B & b) in year 1.


b) Determine the frequency of both alleles (B & b) in year 2.


c) Is this population in Hardy-Weinberg equilibrium? Why or Why not?


d) If the allelic frequencies for a particular gene in a population remain constant from year to year,
what does this mean about the evolution of wool color in this population of sheep?



 6. In a particular species of flower, C1 codes for red flowers, C2 codes for white, with the heterozygous
individuals being pink. (4 pts.)

a. If the frequency of pink individuals in the population was .7126, would you be able to estimate the
 frequencies of the individual alleles in the population? Why or why not?



b. If the frequency of red individuals in the population was .329, what would the estimated frequency of
pink and white individuals be in this same population?




7. Suppose the number of red, pink and white individuals in another population of flowers was 555,
555, and 555 respectively. (9 pts.)

a.  Could this population be said to be in H-W equilibrium? SHOW YOUR WORK!

 




b.  Which flowers could be said to be at an apparent selective advantage?  Why might this be the case?