In: Statistics and Probability
Use the following information to answer questions 43a-43e.
You are studying cannibals in Borneo and want to determine if a specific village population is in Hardy-Weinberg equilibrium with respect to the single-gene locus segregating the two co-dominant M and N blood type alleles (LM,LN). The following are sample data from this population of the cannibals:
Genotype | # individuals |
MM | 325 |
MN | 680 |
NN | 140 |
total | 1145 |
a. What is the observed frequency of each genotype?
b. What is the observed frequency of each allele?
c. Based on b, what would the expected frequency of each genotype be, if the population were under Hardy-Weinberg equilibrium?
d. What is the expected number of individuals of each genotype under H-W equilibrium?
e. Perform a Chi-squared analyses to determine whether the observed genotype numbers are consistent with H-W equilibrium. (To determine the degrees of freedom, use the formula DF = # of genotypes - # of alleles).
a.
The observed frequency of each genotype are,
Genotype | Observed Frequency |
MM | 325/1145 = 0.2838428 |
MN | 680/1145 = 0.5938865 |
NN | 140/1145 = 0.1222707 |
b.
The observed frequency of each genotype are,
Allele | Observed Count |
M | 325 + 680/2 = 665 |
N | 140 + 680/2 = 480 |
Probability of Allele M, p = 665 / 1145 = 0.580786
Probability of Allele N, q = 480 / 1145 = 0.419214
c.
Expected frequency of each genotype be, if the population were under Hardy-Weinberg equilibrium
Genotype | Expected Frequency |
MM | |
MN | |
NN |
d.
Expected number of individuals of each genotype be, if the population were under Hardy-Weinberg equilibrium
Genotype | Expected Frequency |
MM | |
MN | |
NN |
e.
Chi-square test statistic
= 55.22245
DF = # of genotypes - # of alleles = 3 - 2 = 1
Critical value of Chi-square test statistic for df = 1 and 0.05 significance level is 3.84
Since Chi Square test statistic is greater than the critical value, we conclude that there is significant evidence that the observed genotype numbers are not consistent with H-W equilibrium.