01:447:380 Lecture 21: Population Genetics

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olivebee315

11 Dec 2017

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Example: have bright green spots on their feathers and some do not. Let g = green spots, g = no spots. Hardy-weinberg law: allow us to predict genotype frequencies from allele frequencies; 1: random mating, no new mutations, no migration, no natural selection, 2 conclusions, allele frequencies do not change from generation to generation. After 1 generation: genotype frequencies stabilize at p 2 , 2pq, q 2 . If population is in hwe, then alleles are randomly drawn from gene pool to make up genotypes of each generation. Allele frequencies f(g) = p, f(g) = q. Is our population of birds in hwe? (do chi-squared) D. f. = # of genotypes - # of alleles = 3-2 = . If all hwe assumptions hold, this population will be in hwe after 1 generation. Pq/2: conditions that violate hwe, nonrandom mating, positive assortative mating like mates with like, negative assortative mating unlike individuals mate c) Homozygotes always make more of same genotype.

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

1) Which of these probabilities are NOT independent of eachother?

The probability that a student is a sophomore and has brownhair

The probability that when you roll two dice, you will roll a 6before a 2

The probability that it will rain and the probability ofneeding an umbrella

The probability that there will be heavy traffic on BaltimoreAve and the probability you will lose your cell phone

2) We are defining evolution as a "change in allele frequenciesover time". Ironically, the focus of this lab is the Hardy-Weinbergequilibrium - conditions that, if all met, will result in NOevolution occurring. Which of the following are among theconditions that must be met for the Hardy-Weinberg equilibrium toapply perfectly to a population?

A. The population must be very large

B. Individuals must mate at random

C. The alleles must differ in their effects on survival

D. There must be free migration into and out of thepopulation

A & B

A, B, & C

3)In cats, black fur is dominant over any allele for brown fur.If a homozygous dominant cat makes kittens with a heterozygous cat,what is the probability that the first kitten will have brown fur?Report as a proportion, not percentage, e.g., .1, NOT 10%.

The EGLN1 gene helps regulate body oxygen levels. One allele His dominant over h, and helps increase fitness at high altitude(where oxygen is low). In a study of families in Tibet, researchersfound 422 HH individuals, 377 Hh, and 201 hh individuals. The studyshowed that infant mortality was lower in Hh individuals than hh,and lowest in HH individuals.
Is the Tibetan population in Hardy Weinberg Equilibrium at this H/hgene?

What is the most important factor affecting the strength ofgenetic drift?

The frequency of the rarest genotype

The size of the population

The allele frequencies

The genetic diversity in the population

aquamarinerat250

1. If an individual has a genotype of Bb, what types of gametes (sperm/egg) could they produce?
A) B
B) b
C) B or b
D) Bb, BB, bb
E) Bb

2. Which of the following statements is true about phenotypic plasticity, i.e., phenotype variation that is the result of genotype by environment interactions?
A. Phenotypic plasticity is only favored when the parental environment is a good predictor of the offspring environment
B. Since the trait expression of a genotype varies across environments, it cannot respond to selection
C. A variable environment is required for phenotypic plasticity to be selected for
D. A single trait can only ever be plastic or non-plastic within a species
E. Phenotypic plasticity can only occur within a single generation, never across generations

3. With large numbers of genes contributing to variation for a phenotypic trait (e.g. height in humans), the population approaches what kind of distribution for that trait?
A. Mendelian
B. Exponential
C. Binomial
D. Normal
E. Continuous

4. A classic example of phenotypic plasticity is caste determination in social insects. Whether a female ant becomes a worker, soldier, or queen is determined by the food she is fed. Would you say this this an example of G, E, or GxE?

5. In an infinite population, the frequency of the A allele is 0.3 and the frequency of the a allele is 0.7. What is the frequency of heterozygotes?
A. .10
B. .21
C. .30
D. .42
E. .70

6. Blue eyes are a recessive trait caused by an autosomal allele. If there are 180 people with blue eyes in a population of 500 people, what is the frequency of the brown-eye allele? (Assume HWE)
A. .36
B. .40
C. .50
D. .60
E. .64

7. Imagine flower color in diploid roses is determined by a single gene with two alleles, white and red, which are co-dominant so that heterozygotes are pink. Frank is colorblind and can only discriminate between white and colored roses, and knows that his population has 18 white roses and 182 non-white roses. How many of Frankâs roses are pink? (Assume HWE.)
A. 18
B. 21
C. 42
D. 84
âE. 100

8. Imagine flower color in diploid roses is determined by a single gene with two alleles, white and red, which are co-dominant. If Eva's population has 250 white roses, 500 pink roses, and 250 red roses, what is true about this population?

A. It is not in Hardy-Weinberg equilibrium
B. It is under balancing selection
C. It is connected to another population by migration
D. It is in Hardy-Weinberg equilibrium
ââE. White is a recessive lethal

9. 9% of a population is unable to taste the compound PTC, which is a recessive trait. Assuming HWE, if two carriers of the non-tasting allele had a baby what is the probability that it would be unable to taste PTC?
A. 0.09
B. 0.25
C. 0.30
D. 0.50
E. 0.70

10. (Adapted from: Christensen, A. C. (2000). Cats as an aid to teaching genetics. Genetics, 155(3), 999-1004.) ss cats have no white fur, Ss cats generally have <50% white fur, and SS cats generally have >50% white fur (cats who are 100% white are scored as dominant white and can't be scored for piebald spotting). The S allele is incompletely dominant, but variably expressed, so there is a more-or-less continuous gradient of white pigmentation in populations. You and your friends score all non-white cats up for adoption: http://www.adoptapet.com/cat-adoption/search/50/miles/48824 and find there are 160 with >50% white fur, 350 with <50% white fur, and 490 with no white fur. Which of the following statements is definitely true:

A. The population is in Hardy-Weinberg equilibrium
B. The population is not in Hardy-Weinberg equilibrium
C. There is selection acting on the population
D. It is impossible to know if the population is in Hardy-Weinberg equilibrium
E. Fur color is not a heritable trait and therefore cannot evolve

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01:447:380 Lecture 21: Population Genetics

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