1) In a survey of a population of a certain species of field rodent, the followi
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Question
1) In a survey of a population of a certain species of field rodent, the following data was collected: Black hair (genotype B,B)-18 - Brown hair (genotype B,B)-62 Yellow hair (genotype B,B,)-34 What are the frequencies of the two alleles? Is this population in a Hardy-Weinberg equilibrium? Test your hypothesis with a X2-test. 2) In a separate, equally sized geographical population of the same species, a rather different set of data was gathered: Black hair, 24; Brown hair, 51; Yellow hair 25 What are the frequencies of the two alleles? Is this population in a Hardy-Weinberg equilibrium? 3) In humans, blue eye colour (B) is completely dominant to brown eye colour (b) [a hopeless oversimplification for argument's sake only]. In a certain population, the following data was gathered Blue eyes, 68; brown eyes, 32 What are the frequencies of the two alleles? Is it possible, in theory, to determine whether this population is in a Hardy-Weinberg equilibrium from the data given alone? (Hint: how many heterozygotes are among the blue eyed individuals?) 4) Consider the two populations in questions 1) and 2), above. Up to now they have been entirely separate, with no migratory contact between them. Suppose reciprocal migration begins between these two populations, at a level of m = 0.05. That is, at each generation they exchange 5% of their members. Providing that no other factors direct allele frequencies, the populations will eventually become homogeneous. What will the allele frequencies be at this point? Show this trend graphically. On a single graph, show the frequencies of one of the alleles at each generation in each population. How would these curves change if the rate of migration were m = 0.01? m = 0.10? 5) What would be the heterozygosity of the two populations in questions 1) and 2)? What would be the fixation index between the two populations? On a single graph, depict the trends in heterozygosity in each subpopulation, and the trend in fixation index, after each round in migration, as described in question 4) 6) Consider a population of 20 individuals. A certain locus is polymorphic in this population for two selectively neutral alleles (i.e. distinct, but do not affect fitness), with frequencies f(A)-0.70 and fA2)-0.30. Because the population is so small, random genetic drift will probably occur, with the result that one of the two alleles will eventually be lost. What do you suppose is the probability that the A, allele will be lost? that the A, allele will be lost? How would this change if the population consisted of 2,000 individuals?Explanation / Answer
1) Black (B1B1) - 18, Brown (B1B2) - 62, Yellow (B2B2) - 34
Total = 114
Frequency of allele B1 = [B1B1 + ( B1B2 / 2)] / 114 = [18 + (62/2) ] / 114 = 49 /114 = 0.43 = p
Frequency of allele B2 = [B2B2 + ( B1B2 / 2)] / 114 = [34 + (62/2) ] / 114 = 65 /114 = 0.57 = q
Hardy - Weinberg Equilibrium :
p2 + 2pq + q2 =1
0.185 + 0.490 + 0.325 = 1
Therefore, the population is in Hardy - Weinberg Equilibrium
2)
Black (B1B1) - 24, Brown (B1B2) - 51, Yellow (B2B2) - 25
Total = 100
Frequency of allele B1 = [B1B1 + ( B1B2 / 2)] / 100 = [24+ (51/2) ] / 100= 49.5 /100 = 0.495 = p
Frequency of allele B2 = [B2B2 + ( B1B2 / 2)] / 100 = [25 + (51/2) ] / 100 = 50.5 /100 = 0.505 = q
Hardy - Weinberg Equilibrium :
p2 + 2pq + q2 =1
0.245 + 0.50 + 0.255 = 1
Therefore, the population is in Hardy - Weinberg Equilibrium
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