Allele A1 Assignment-S23_updated

docx

School

University of Cincinnati, Main Campus *

*We aren’t endorsed by this school

Course

102H

Subject

Biology

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by ChiefPencil13822

Names of Group Members: Keta, Sydney, Maggie, Raeh AlleleA1—a computer simulation (20 pts) All of the model population conditions and many variations can be investigated and displayed using the AlleleA1 computer program. Depending on the class situation, your instructor may demonstrate the following exercises for you or you may do the exercises yourself. Link to AlleleA1: https://faculty.washington.edu/herronjc/a1/ The AlleleA1 computer program models the allele frequencies of different genotypes over many generations, depending upon how certain parameters are set. Things to know about the program:  The starting frequency of allele A1 can be set anywhere from 0 to 1. If the frequency of Allele A1 is 0.2, what is the frequency of its complementary allele A2?  Fitness models natural selection . Where no natural selection occurs, the fitness is perfect at 1.0. To decrease the fitness of A1A1, A1A2, or A2A2, then decrease the fitness value to simulate natural selection against organisms that possess the unfit genotype.  In a similar way, you can change the mutation rate, migration rate, population size, and inbreeding coefficient (i.e., non-random mating ).  You can also increase or decrease the number of generations that the simulation models by clicking on the arrow to the lower right of the graph. This program computes the results of the standard algebraic terms: p 2 = frequency of AA 2pq = frequency of Aa q 2 = frequency of aa 1a) First run the Hardy-Weinberg Model (refresh your page, H-W should be the default settings and produce a green line straight across the graph). Note how each of the parameters be set in order to model a population in Hardy-Weinberg. Include a screenshot of the resulting graph: (1 pt)

Notice that the line graph is the frequency of one of the alleles in the gene pool. How do you find the frequency of the other allele? We use the Hardy-Weinberg Equation (p + q = 1) to find the frequency of the other allele in the gene pool. Since the frequency of allele A1 is 0.5 in the above graph, frequency of the other allele would be 1 – 0.5 = 0.5. 1b) Change the ‘starting frequency of A1’ from 0.5 to 0.8. Include a screenshot of the resulting graph below: (1 pt)

Compare the above graphs. What happened when you changed the ‘starting frequency of A1’ from 0.5 to 0.8? The frequency of allele A1 increased on the Y axis from 0.5 to 0.8 shifting the green line upwards. Variations in Population Size: Genetic Drift Demo 2. Set the ‘ starting frequency of A1’ back to 0.5. Now change the parameters to model Genetic Drift . Change the ‘ number of finite populations to simulate’ to 5 (this will run the simulation 5 times), and change the ‘ finite population size ’ to 1000. Below the x-axis of the graph, change the number of ‘Generations to run’ to 100. Include a screenshot of the resulting graph: (2 pts) What is the general result in comparison with the H-W model? The frequencies of the allele start out very to the H-W model (0.5) but with time the frequencies start to differ, but they stay relatively similar to the 0.5(H-W Model) mark. 3. Change the ‘ finite population size ’ to 100 individuals. Run this model five times (number of finite populations set to 5). Include a screenshot of the resulting graph: (2 pts)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

How does this differ from the previous set ? Since it is a more finite population size, the frequencies are more drastic with the frequencies being more extreme. 4. Change the ‘ finite population size ’ to 10 individuals and run the model another five times. Include a screenshot of the resulting graph: (2 pts)

Now what is the difference in results compared to the H-W model? With the finite population size being 10 individuals (smaller population) as compared to 100 individuals in the H-W model, the frequency of allele A1 becomes extreme in relatively lesser generations- gets lost in the populations. This happens for all 5 finite populations. The H-W model on the other hand has a single green line depicting the frequency of allele A1 to be a constant number. 5. The “wandering” of the gene pool in a small population is referred to as Genetic Drift and was originally quantified by Sewall Wright. A population that has lost one of the two alleles is termed “fixed”. The population is said to have reached fixation. a. Can such a population evolve? Explain. (1 pt) No, if the population has reached fixation, mutation is less likely to occur, and nonrandom mating is more likely to occur, making the gene pool smaller. The generations to follow will be less likely to evolve from the small gene pool in the population. Moreover, the variation in the population has reduced, which would inhibit evolution. b. What generalization(s) can be made about the impact on the population as it gets smaller? (1 pt) The chance of evolution occurring as a population gets smaller will decrease the possibility of evolution, since a larger population is more ideal for evolution. A large population may allow for a larger gene pool, larger gene pools allow for better chances of variation in a population. Variations in Selection Pressure: Natural Selection Demo

Now change the parameters to model Natural Selection . Begin by refreshing the webpage to reset the parameters to default. Then, follow the instructions below in #s 6 and 7. Run each selected situation twice (set ‘ number of finite populations to simulate’ to 2 to be sure of the effect. Carefully note the scales of the graph. It may be helpful to run the simulation for fewer generations (you can change this below the x-axis of the graph) to see any differences. 6. Selection against the dominant allele: a. Model natural selection against the dominant allele A1 with fitness at 0.5 for A1A1(homozygous dominant) and A1A2 (heterozygous). Include a screenshot of the resulting graph: (1 pt) b. Selection against the dominant with fitness at 0 for A1A1(homozygous dominant) and A1A2 (heterozygous). Remember, it may be helpful to run the simulation for fewer generations. Include a screenshot of the resulting graph: (1 pt)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

c. What was the effect of the change in fitness? How do the above graphs compare to the H-W model? How do these graphs compare to each other? (2 pt) The A1A1 and A1A2 were not able to transfer their genotypes as effectively because we reduced the relative fitness and consequently the A1 allele got lost in the gene pool. In the H-W Model the slope is at a constant 0.5 but in the graphs above there is a downward slope. The reason for this is because essentially the homozygous dominant and heterozygous genotypes are at 0 and the only possible way for this population to survive is with the homozygous recessive genotype. The second graph has a steeper slope than the first graph’s slope and the population in the second graph reaches fixation earlier than the population in the first graph. This is because the relative fitness of A1A1 and A1A2 is lower for the second graph. 7. Selection against the recessive allele: a. Re-set the fitness for A1A1 and A1A2 to 1.0. Model selection against the recessive allele by changing the fitness to 0.5 for allele A2A2. Include a screenshot of the resulting graph: (1 pt)

b. Selection against the recessive with fitness at 0 for aa . Remember, it may be helpful to run the simulation for fewer generations. Include a screenshot of the resulting graph: (1 pt)

c. What was the effect of the change in fitness? How do the above graphs compare to the H-W model? How do these graphs compare to each other? (2 pt) The A1A1 and A1A2 were able to transfer their genotypes effectively because we increased the relative fitness and consequently the A2 allele got lost in the gene pool. In the H-W Model the slope is at a constant 0.5 but in the graphs above there is an upward slope. The reason for this is because essentially the homozygous dominant and heterozygous genotypes are at 1.0 and the homozygous recessive at 0.5 (& 0). This means that the only gene that was inheritable was the A1. The second graph has a steeper slope than the first graph’s slope and the population in the second graph reaches fixation earlier than the population in the first graph. This is because the relative fitness of A2A2 is lower for the second graph. d. Most importantly, what was the difference between selection against the dominant phenotype and selection against the recessive? (2 pts) When selection against the dominant phenotype was done, A1 allele got lost in the population. Whereas, when selection against the recessive phenotype was done, fixation was reached but the frequency of allele A1 increased which meant A1 was more abundant in the population. Terminology to review for upcoming 25-point exam : Evolution: the change in allele frequencies between generations over time. Population: a group of individuals of the same species that inhabit the same area while interbreeding with each other Genetic Drift: a random change in the allele frequency within a population due to a random event Hardy-Weinberg Equilibrium: the genetic variation within a population will remain the same from one generation to the next without any disrupting components. Nonrandom Mating: individuals select their mate for their specific phenotype or genotype (may be similar to their own) Gene Flow: movement of an organism as well as their genetic material into a different environment Immigration: an organism has found and established an environment that is suitable for them

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Genotype Frequency: how often a specific genotype is present in a population Emigration: an organism leaves its current environment because it is not suitable for said organism Mutation: a change in the DNA sequence that occurs randomly Natural Selection: whether an organism adapts to its environment for survival Phenotype Frequency: how often a phenotype appears in a population Genotype: the genotypic pattern of an individual Phenotype: the physical characteristics of an individual Gene Pool: all genes present in a population Allele: genes found on the same part of the allele, may arise from a mutation