The figure below shows the frequency of a dominant and beneficial allele over 400 generations in 10 simulated populations of 100 individuals. The allele A1 is one of two alleles at this locus. In the simulations, the allele A1 gives a 1% fitness advantage to the A1A1 and A1A2 genotypes compared to the A2A2 genotype. For reference, the expected trend in the frequency of A1 in an infinitely large population is shown. What could be said of allele A1 based on the trend in the 10 simulated populations? Frequency A1 Allele Infinitely large population 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 50 100 150 200 250 300 350 Generations Select one: a. The allele A1 is experiencing more drift than the allele A2 b. The allele A1 reaches fixation in most simulations c. The allele A1 is beneficial in some populations but not in others d. The allele A1 is not evolving e. The allele A1 is effectively neutral
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The allele A1 is experiencing more drift than the allele A2: This statement is not necessarily true, as the graph shows that the frequency of A1 is increasing over time in most simulations, which indicates that it is not just experiencing random drift. b. The Show more…
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Scenario 2. Selection Against a Dominant Allele Consider a gene evolving in a population with two alleles, A1 and A2. In the current generation, the frequency of allele A1 in the population is given by p = 0.5 and that of allele A2 is given by q = 0.5. A1 is the dominant allele, and the fitness of each of the genotypes (as measured by the frequency by which the zygotes of that phenotype survive to adulthood), are as follows: A1 A1 ω11= 0.825 A1 A2 ω12 = 0.825 A2 A2 ω22= 1.00 Answer the following questions based on this information. What is the selection coefficient (i.e., strength of selection), s, against the homozygous dominant genotype? What is the current average fitness of the whole population? What will be the frequency of the dominant allele A1 in the second generation? (I.e., the next generation following the current one?) What will be the average fitness of the whole population in this subsequent generation? True or False: Through selection against the dominant allele (as outlined in this example), the average fitness in the population is increasing.
Madhur L.
In a large, isolated population of an insect species, a specific gene locus has one dominant allele (A) and one recessive allele (a). The genotype frequencies of the gene were collected for ten generations, as shown in Table 1. Table 1. Genotypic frequencies over ten generations in an insect species | | AA | Aa | aa | | :--- | :--- | :--- | :--- | | Generation 1 | 0.47 | 0.43 | 0.10 | | Generation 5 | 0.32 | 0.60 | 0.08 | | Generation 10 | 0.20 | 0.75 | 0.05 | Which of the following could best account for the change in genotypic frequencies over the ten generations? (A) Because the A allele is unstable, over the course of the study most of the A alleles mutated to become a alleles. (B) The population is in Hardy-Weinberg equilibrium, which allows for changes in genotypic frequencies every generation. (C) The population is not exhibiting random mating between individuals. (D) The population is becoming extinct because the a allele is disappearing.
Josee P.
Part IV. Now, let's consider dominant/recessive alleles. We are going to look at what happens to a deleterious A1 allele in the population. Input the following parameters: Starting frequency of A1: 0.1 Fitness of A1A1 = 0.90 Fitness of A1A2 = 1 Fitness of A2A2 = 1 Populations size = Infinite (just type this in the box) 7. Based on the input parameters is the A1 allele dominant or recessive? How can you tell? 8. By assuming an infinite population size, what evolutionary force are we ensuring does not have an effect? (g) Carry out the simulation one time for 500 generations and then once for 10,000 generations. Record your data. 9. Is the deleterious recessive allele eliminated from the population in either of the simulations? Please explain why or why not? (h) Now, change the population size to 100 (leave other parameters the same) and carry out the simulation for 500 generations 15 times. Record your data. 10. Compare the results of these simulations with those from "g" above. If there is a difference, please explain what accounts for the difference.
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