Biology

Genetics 303 Dr. Joe Staton Fourth exam—take home Answer on separate paper, show all work, and be neat in the reporting of answers. STAPLE YOUR RESULTS! 1. In a human population, the genotype frequencies at one locus are 0.75 AA, 0.2 Aa, and 0.05 aa. What is the frequency

of the A allele [f(A)] and a allele [f(a)] for the population? Are they in Hardy-Weinberg equilibrium? 2. Calculate the number of heterozygotes in a population with p = 0.55 and q = 0.45 (at time = 0). After 4 generations of

inbreeding between siblings (F = 0.25) in a population of 1000. 3. Human albinism is an autosomal recessive trait. Suppose that you find an isolated village in the Andes where seven

people are albino. If the population size of the village was 783 and the population is in Hardy-Weinberg equilibrium with respect to this trait, how many individuals are expected to be carriers (heterozygotes)?

4. A boatload of Swedish tourists, all of whom bear the MM blood group, is marooned on Haldane Island, where they are

met by an equally sized population of Islanders, all bearing blood group NN. In time, the castaways become integrated into Island society. Assuming random mating, no mutation, no selection (based on blood group), and no genetic drift, what would you expect the blood group distribution to be among 1500 progeny of the new Haldane Island population?

5. You identify a population of mice (Peromyscus maniculatus) on an island. Their coat color is controlled by a single

gene: BB mice are black, Bb mice are gray, and bb mice are white. You take a census of the population and record the following numbers of mice:

Black 507 Gray 546 White 147 (a) What are the frequencies of the two alleles? (b) What are the Hardy-Weinberg equilibrium frequencies for these three phenotypes? (c) A heat wave hits the island. All 507 mice with black fur die from heat stroke, but the other mice survive. What are the

new allele frequencies for the population? (d) If the population suffers no further cataclysms after the heat wave, and the surviving animals mate randomly, what will

be the frequency of mice with black fur in the next generation? (e) If the climate is altered permanently, so that mice with black fur die before reproducing, which following statement is

correct? (1) At Hardy-Weinberg equilibrium, f(B) will equal 0.135. (2) The fitness of mice with gray fur (ωBb) must be equal to 0.5. (3) The fitness of mice with black fur (ωBB) is 0. (4) The B allele will disappear from the population in one generation. (5) The B allele will disappear from the population in two generations.

6. Which of the following are requirements for evolution by natural selection? Explain your answer. I Environmental change II Differential survival and reproduction III Heritability of phenotypic variation IV Variation in phenotype V Sexual reproduction

A) II, III, V B) II, III, IV C) I, II, IV D) III, IV, V E) II, IV, V

7. Which of the following processes is the source (origin) of genetic variation within populations? A) Reproductive Isolation B) Asexual reproduction C) Selection D) Mutation E) Genetic drift

Explain your answer including a description of what the others do to variation. 8. If the population (14,926 in 2013) of folks in Perry, GA, have an f(a) = 0.1 and folks in Valdosta, GA, has a f(a) = 0.7,

then how many people from Valdosta, GA, would have to migrate to Perry to increase the population to a f(a) = 0.15?

9. What is the Ne of a population with the following annual censuses, [note the drop in size due to 2005 being an extreme

drought year]? 2001: 10,000 2002: 9,700 2003: 8,800 2004: 4,600 2005: 700 2006: 2,400 2007: 3,800 2008: 7,650 2009: 8,400 2010: 9,700 2011: 10,110 2012: 11,060

10. Consider the following populations that have the genotypes shown in the following table: Population AA Aa aa 1 1.0 0.0 0.0 2 0.0 1.0 0.0 3 0.25 0.50 0.25 4 0.25 0.25 0.50 5 0.32 0.36 0.32 6 0.04 0.32 0.64 7 0.64 0.32 0.04 8 0.9025 0.095 0.0025

a. What are p and q for each population? b. Which of the populations are in Hardy-Weinberg equilibrium? c. Populations 1 and 2 have a tree fall across their islands so that individuals can cross. If equal numbers of the

individuals occur on each island, what is the new population’s allele frequencies and genotype frequencies after one generation of random mating?

d. In population 3, the a allele is less fit than the A allele, and the A allele is incompletely dominant. The result is that AA is perfectly fit (= 1.0), Aa has a fitness of 0.85, and aa has a fitness of 0.65. With no mutation or migration, graph the allele frequency of the a allele for 10 generations under selection (e.g., Time 0 = q above, Time 1 = first generation after selection)

e. In population 8, the population size gets radically reduced to 200 individuals, total. What is the most likely fate of the “a” allele, and what genetic principle would lead you to believe that the case?

11. You are given the following genetic data matrix of distances for crustaceans calculated for a region of the mtDNA called the 16S rDNA:

Brine Shrimp Striped-leg hermit King Crab Soldier crab Flat-claw hermit Long-clawed hermit Brine Shrimp ─ Striped-leg hermit 0.354 ─ King Crab 0.309 0.260 ─ Soldier crab (hermit) 0.321 0.268 0.067 ─ Flat-claw hermit 0.337 0.245 0.108 0.111 ─ Long-clawed hermit 0.312 0.249 0.090 0.096 0.044 ─ Calculate the average distance and draw the resulting UPGMA tree based on these distances. Write a brief interpretation of the branching pattern in the tree. 12. You digest a linear piece of DNA with two restriction enzymes, BamH1 & Sma1, and get the following sized fragments (in kb [kilobases]): BamHI SmaI BamHI & SmaI 13 kb 11 kb 10 kb 6 kb 5 kb 5 kb 3 kb 3 kb 1 kb Draw the appropriate restriction fragment map based on this data labeling all restriction sites. Extra Credit: You have a population of gribbets in captivity where the adults have a genetic frequency of f(A)=0.5 and f(a) = 0.5. When randomly mated, they have offspring that are represented in the following frequencies: f(AA) f(Aa) f(aa) 0.194444 0.555556 0.25 But you notice that the total generational reproduction level is only 90% that of wild populations (i.e. the ω is only 0.9). Work backwards to figure out the type of condition from table 25.5, and calculate the equilibrium frequency for the a allele (q). Give it a try! Partial credit for attempts…

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