Keron Persaud Genetic Drift and Natural Selection Review Questions

Mark all that are true regarding interpretation of w values. V When w > 1 (significantly greater than 1), the region being examined has been experiencing mutations non-randomly (more non-synonymous mutations than synonymous) O w< 1 (significantly less than 1) sugggests that purifying selection has taken place. V w = 1 indicates that neutral evolution is definitely occuring A With w = 1 we cannot reject the hypothesis that the locus is evolving neutrally. However, it is possible that different sites within this locus are experiencing unique selection pressures (some purifying selection and others positive selection), and the result of these cancelling each other out creates the appearance of neutral evolution.

Answer the following genetics questions

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1. Present possible evidences that genetic drift affect human population. Discuss this evidences comprehesively. Do not just copy from somewhere, I need evidences that shows that genetic drift has a role in human evolution. Thank you!

Small population size causes genetic drift because ofchance sampling of different alleles from one generation to the next. We can predict how much geneticdrift occurs for a given population size using binomialsampling statistics. With a population of size N, wecan estimate that 95% of the time the allele frequency(p) in the next generation will be withinthe confidence interval of p ± 1.96 (√p(1 − p)2N ),where p(1 − p)2Nis an estimate of the statistical variancein allele frequencies from one generation to the nextwith random sampling of 2N alleles each generation. a. What is the confidence interval for p = 0.5 whenN = 100,000?b. What is the confidence interval for p = 0.5 whenN = 10?c. How are the results in parts (a) and (b) related tothe consequences of a population bottleneck?

Match Column A with Column B. The ultimate source of new alleles A. Mutation this force is causing a small percentage to the evolution process B. Natural selection most are lost due to chance or to detrimental effects on C. Genetic drift phenotype D. migration |In its absence, allele frequencies in different subpopulations will diverge Source of new alleles entering local population from other subpopulations v The movement of organisms among subpopulations - v Genotypes best suited to survive and reproduce in a particular environment of the offspring | The genotypes that promote survival are favored and contribute disproportionately to the offspring of the next generation known as evolutionary adaptation | The random, undirected changes in allele frequencies, especially in small populations.

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77)Each graph below shows the frequency of the A allele in six simulated populations (each line in a graph) over 500 generations. Each of the six simulations within a graph were done with the exact same settings of relative fitness among the genotypes and population size BUT these settings differed between the four graphs. Which graph shows a situation in which the effect of selection is the highest relative to the effect of drift? C   D   A   B

5. Describe how the authors accounted for age in the methods. Why is this important? 6. Explain the results shown in Fig. 1. What was the value for h²? a. For what specific trait, therefore, do they demonstrate heritability? b. Can that trait evolve? C. What if they studied the same trait in a different population and got a value of h²=0.4. Which population would evolve faster? 7. Explain the authors' reasoning for rejecting body condition affecting parasite load (see 3rd paragraph of Discussion). Draw a hypothetical graph that corresponds to their description of why they rejected the hypothesis. 8. Describe the problem of uncertain paternity with respect to this study. How could the authors definitely determine paternity and make sure they correctly identified each offspring's parents? 9. Do you agree or disagree with the authors' conclusions? Why or why not?

1. Certain flowers are either red (dominant) or white (rr). 91% of the flowers are red. Using the equations, calculate the frequency of the R allele. First you replace R and r for p and q. Thus we know that q2 = .09, because only the homozygous recessives will be white.  *changed away from percentages to work the math more easily*         What is the frequency of the R allele in this population? 2. In a coastal city in Nigeria, the incidence of Sickle-Cell disease is 4% of the population. Based on this information, what is the frequency of this allele in the population of that city? 3. In a given human population, only the "A" and "B" alleles are present in the ABO system; there are no individuals with type "O" blood or with O alleles in this particular population. If 200 people have type A blood, 75 have type AB blood, and 25 have type B blood, what are the alleleic frequencies of this population (i.e., what are p and q)? 4. An allele W, for white wool, is dominant over allele w, for…

Mechanical Isolation O Gametic Isolation A species of insect has a gene that determines whether the legs have brown stripes or black stripes, with brown being completely dominant over black. There are 76 BB insects, 50 bb insects and 124 Bb insects. If there were 90 brown individuals and 15 black individuals in the parent population, what can be concluded about the population?" O The population is not evolving. O The population is evolving Stabilizing selection is occurring. O The population is in Hardy-Weinberg equilibrium. The elephant and the crocodile evolved from a common ancestor. Which

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5. The Hardy-Weinberg Principle states that gene frequencies in a population are overall conserved. Consider blood alleles A (with proportion p in the population), B (with proportion q in the population), and O (with proportion r in the population). Blood type is a mix of these genes so the possible blood types are AA, BB, OO, AB, AO, and BO. The proportion of people with mixed alleles is P = 2pq + 2pr+2qr. If 1/6 of the population has blood allele A, what is the maximal proportion of people with mixed blood alleles.

Based on your Figure 3 (i.e. the HF genotype histogram), we would have assumed thatthe increase in the HF genotype would have been consistent (i.e. no variation infrequency) between trials at update 500 due to positive selection using a 0% mutationrate. Why was this not the case? Briefly explain why variation occurred.

1. 9. You are a genetiCıst studying a population of 100 barn swallows. You are particularly interested in one gene, and upon examining the alleles present, you find one allele is quite common, accounting for 80 of the alleles in this population. What is the frequency of this allele in the population? 4. 5. The ability to breathe fire in dragons is controlled by a single gene with two alleles. The fire-breathing allele (F) is dominant to the non-fire breathing allele (f). In a population of 600 dragons, 150 dragons are non-fire breathing (ff) and the rest can breathe fire (either FF or Ff) The population is in Hardy-Weinberg equilibrium. The frequency of the dominant allele (F) is represented by "p and the frequency of the recessive allele (f) is represented by "q". Recall the allele frequency is p+ q = 1 and the Hardy-Weinburg equation is p2 + 2pq + q2 = 1 (2 pts). What is the frequency of the recessive allele (f)? Hint: you can figure out the frequency of ff, which is equal to q2, but…

1. What happened to observed allele frequencies in each population? (only answer this question number 1, below is a data) Data: a. observed frequency of alleles of F1 population without natural selection: A=0.43 a=0.57 b.observed frequency of alleles of F2 population without natural selection: A=0.52 a=0.48 c. observed frequency of alleles of F1 population with natural selection: A=0.69 a=0.31 d. observed frequency of alleles of F2 population with natural selection: A=0.62 a=0.38

25. Answer the following questions based on the facts and inferences related to natural selection that we discussed in class, as well as the simulations you performed with the Evodots lab. If individuals vary, and variation affects survival and reproduction, and variation is heritable: there will be natural selection resulting in evolution. there will be no natural selection, but there will be evolution due to natural selection. there will be natural selection, but it will not result in evolution. there will be no natural selection, and there will be no evolution due to natural selection.   24. Answer the following questions based on the facts and inferences related to natural selection that we discussed in class, as well as the simulations you performed with the Evodots lab. If individuals vary, and variation affects survival and reproduction, but variation is not heritable: there will be natural selection resulting in evolution. there will be no natural selection, but…

n class we investigated the reason cystic fibrosis is maintained in the human population in higher frequency than we expected given the deleterious effects of being homozygous at the CFTR gene. We calculated the actual mutation rate of the CFTR gene to be 6.7 x 10-7. The mutation rate expected under mutation-selection balance was 4 x 10-4. What is the most plausible explanation as to why cystic fibrosis is maintained in the human population at a higher frequency than we expect?   a. Negative selection against the CFTR deleterious alleles is too weak to eliminate the alleles from the human population.   b. Positive selection for the CFTR deleterious alleles is likely occurring in response to some other selective pressure in the human population, possibly resistance to typhoid fever.   c. The CFTR gene has an exceedingly low mutation rate causing humans to have no genetic variation at that gene.   d. The CFTR gene has an exceedingly high mutation rate and that is…

Under what scenaries is genetic drift most potent as an evolutionary process? how do factors like population size and initial allele frequences affect likelihood of an allele being lost from a population (or becoming fixed)?

#27 a.) which of the following are both forces of evolution 1. Selection and Mutation 2. Selection and infinite populations 3. Gene Flow and Mendelian genetics 4. Migration and Random mating   b.) In this part we want to know which of the following are assumptions of the Hardy Weinberg equilibrium model? Mark all the correct assumptions.  1. there is no mutation 2. all genotypes have different fitness 3. sexual selection 4. random mating

Explain genetic drift (and it’s various types) as a force of evolution (how does genetic drift contribute to biological change?)

1.Describe the ways that gene number or gene position on a chromosome, might be altered? What implications might that have on evolution? 2.What are the conditions that must be met for a population to stay in Hardy-Weinberg equilibrium? What happens if these conditions are not met? 3.What type of selection would most likely benefit heterozygous individuals and which will result in a population losing alleles: directional, disruptive, or stabilizing? Explain. 4.How might frequency dependent selection and the heterozygote advantage help maintain multiple alleles in a population? 5.Describe the theory of evolution by natural selection. Include terms like "excess reproduction, genetically distinct offspring, changing allele frequencies, and adaptive traits".

Define genetic drift and give three ways in which it can arise. Whateffect does genetic drift have on a population?

1. What is the expected time to fixation in generations for a new mutation in a diploid population (like humans) with an effective population size of 50? This new mutation is neutral and has no impact on fitness (e.g. synonymous polymorphism). Assuming the mutation isn’t lost immediately, will it reach fixation faster in a population of Ne=500 or Ne=5,000 and why?

1. Did both populations (with and without natural selection) conform to Hardy-Weinberg equilibrium? What happened to observed allele frequencies in each population? Only answer question 1 below is an information about the question . Data result of Testing Hardy-Weinberg Equilibrium with natural selection Chi-square of results from bean model for F1: a. Total of (obs-exp)2/exp = Chi- square value for F1 = 3.1 The resulting chi-squared value is 3.1. b. For a p-value of 0.05 and 2 degrees of freedom, the critical value is 5.99. Our value of 3.1 is smaller than the critical value (5.99), Thus, we cannot reject the null hypothesis. c. The population is in Hardy-Weinberg Equilibrium, and is not evolving or It does conform to null hypothesis. Chi-square of results from bean model for F2: a. Total of (obs-exp)2/exp = Chi- square value for F2 = 6.5 The resulting chi-squared value is 6.5. b. For a p-value of 0.05 and 2 degrees of freedom, the critical value is 5.99. Our value of…

1. Does genetic drift affect natural selection? Yes or No? Discuss and explain it thoroughly. Do not just copy it from somewhere, please.

1.     A sample of 600 individuals from a population is examined for the presence of the HindIII polymorphism in an autsomal Sca gene. There are two alleles of Sca gene, A and a. The results are 14 individuals are AA, 212 are Aa, 374 are aa. Please answer the following questions accordingly?  How many alleles are present in the gene pool in the sample population fort he Sca gene? What are the genotype frequencies? What are the frequencies of A and a alleles? What are the expected numbers of the three genotypes, assuming random

2. Based on the class data from Experiment I, generally speaking, how does population sizeaffect genetic drift?

The evolution of a qualitative trait in reponse to natural selection is described by the following equation,       R=h2 S a) What  is S and what does it measure?  b) Describe a study that woukd allow you to estimate S in a real population.