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oliveeagle546Lv1

28 Sep 2019

Under the Hardy-Weinberg model, a population will reach Hardy-Weinberg frequencies in a single generation. This model assumes that genotype frequencies are the same in both sexes: Consider a situation where this is not the case. A researcher creates a new Drosophila population by selecting 2000 males from a stock population fixed for the dominant A allele at a neutral locus A and 2000 females from a different stock population fixed for the recessive a allele at the A locus. The A allele is located on an autosome, not a sex chromosome. These individuals then mate among themselves.

a) Assuming that there is no mutation, what genotype frequencies will be observed in the first offspring generation?

b) How long will it take this population to reach Hardy-Weinberg proportions?

c) Explain why this population took two generations instead of one to reach Hardy-Weinberg equilibrium.

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premgiriLv10

27 Feb 2023

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Related questions

Q1. What are alleles?Different forms of the same gene.Different genes.The different characteristics of an organism.Genes found only in humans.Q2. If you add up the frequency of homozygotes + the frequency of heterozygotes for one gene (i.e. at one locus) in a population, what number do you get?Q3. People who are heterozygous for the sickle-cell allele:Are susceptible to malaria but not sickle-cell anemia.Are susceptible to sickle-cell anemia but not malaria.Are not susceptible to either sickle-cell anemia or malaria.Are susceptible to both sickle-cecell anemia and malaria.Q4. In the case study in this lab, which genotype is represented by "2pq" in the Hardy-Weinberg equation?Homozygous HbAHomozygous HbSHeterozygous HbA/HbSNo specific genotypeQ5. Suppose that, in an isolated village, the proportion of individuals that have sickle-cell anemia is 0.1 (or 1 of every 10 people). What proportion of the population should be sickle-cell carriers, according to Hardy-Weinberg expectations?Q6. When you simulated the elimination of malaria at the beginning of the lab, once the allele frequencies stabilized, what was the frequency of the HbA allele?Q7. When you investigated regional differences, what was the frequency (over many generations) of the HbS allele in the village in the "slightly wet" part of Africa?Q8. What is the number of deaths due to sickle-cell anemia in a region without mosquitoes expected to be?Very lowVery highModerateRelated to the frequency of malaria allelesQ9. As long as there are multiple alleles of a gene in a population, why will the frequencies of the alleles always change over time?Because natural selection changes all allele frequencies in populations over time.Because genetic drift causes random fluctuations of allele frequencies in populations.Because diseases will eliminate some of the alleles, generating fluctuations in their frequencies.Because allele frequencies fluctuate before the alleles eventually become fixed.Q10. Imagine a huge population with a gene that has ten functionally equivalent, neutral alleles. A small but genetically representative group of individuals from the big population is transported to an island, forming a small population. Which of the statements below best describes what will likely happen over time, and why?Because natural selection doesn't act on neutral alleles, the frequencies in the two populations should remain the same over time.Genetic drift will cause one allele to first become fixed in the island population, and later to become fixed in the original, large population.Genetic drift will result in the allele frequencies of the two populations diverging over time, with alleles being lost sooner in the island population.The allele frequencies of the two populations will change similarly due to a combination of genetic drift natural selection.

indigosnake469

Butterflies have a Z/W mechanism of sex determination. In thissystem, females are the heterogametic sex, so females are ZW andmales are ZZ. Papilio glaucus, the Eastern Tiger Swallowtail, isfound throughout the eastern United States. Papilio canadensis, theCanadian Tiger Swallowtail, is found throughout Southern Canada andthe Northern United States. The two species are known to hybridizewhere their ranges overlap near the Great Lakes.

For butterflies living in seasonal environments, it is importantto correctly time the diapause â a state of physiological dormancythat allows them to survive the winter. P. canadensis lives incolder climates and therefore has only one generation per year andan obligate diapause; all pupae of this species diapause from latefall until the next spring, when they resume development. In P.glaucus, most pupae diapause only in response to cold temperatures;as long as weather remains warm, they continue to develop. However,some P. glaucus pupae show obligate diapause similar to P.canadensis. The gene that controls diapause in Papilio is locatedon the Z chromosome, and obligate diapause is specified by therecessive allele ob.

A population of P. glaucus near Lake Michigan is atHardy-Weinberg equilibrium. You have found that 9% of the malepupae show obligate diapause.

(1 point) What is the percentage of female pupae that showobligate diapause? (Show how you calculated this).

(1 point) What is the frequency of the ob allele in males and infemales?

(1 point) What will be the frequency of obligate diapause pupaein the next generation in the absence of selection, in eachsex?
Males:

Females:

(8 points) Winter came early and suddenly this year. Pupae thatwere in diapause because of the ob allele were safe, with arelative fitness of 1. Pupae that had not diapaused were much moresusceptible to the cold and most of them died leaving them with arelative fitness of 0.2. All adults and other larvae died. What isthe new frequency of the ob allele in the next generation? Inmales:

In females:

You now bring P. canadensis and P. glaucus back to the lab tocarry out some controlled crosses. The P. canadensis populationthat you chose is fixed for the ob allele. The P. glaucuspopulation that you chose is fixed for the alternative dominantallele at this locus that allows for environmental determination ofdiapause. From the following matings, what is the frequency ofdiapausing pupae that you would expect? (Show how you calculatedthis).

(2 points) Male canadensis x Female glaucus

Males:

Females:

(2 points) Male glaucus x Female canadensis

Males:

Females:

P.glaucus is highly palatable to predators. Females come in twoforms: a yellow form that looks identical to males and has somelevel of crypsis and a dark form, which mimics the unpalatablebutterfly Battus philenor. This trait is specific to females andthe locus that determines the phenotype is biallelic and located onthe W-chromosome.

(1 point) What form of mimicry is this?

(3 points) You are comparing two populations of P.glaucus foundin different regions. What factors do you think might influence therelative fitness of the two morphs?

(1 point) What type of selection would you expect to act on thegene responsible for color morph determination? (check one)

Negative Frequency Dependent Selection

Positive Frequency Dependent Selection

Balancing Selection
Directional Selection