Homework Answers
Fixation of dominant allele in a population means, there will be no recessive allele in that population. Only dominant alleles remain in the population.
Natural selection can decrease or increase allele frequency in a population. It can leads to speciation by accumulation of adaptive genetic differences among reproductively isolated populations. Natural selection can increase the frequency of dominant allele and decrease the frequency of recessive allele. But is cannot totally eliminate recessive allele even if the allele is lethal.
Because Homozygous recessive could be eliminated by natural selection but recessive allele will still remain in the population in heterozygous individuals. Heterozygous individuals have dominant phenotype, but they also have recessive alleles. So natural selection cannot drive dominant allele to fixation within a population.
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3. Why can't natural selection alone drive dominant alleles to fixation within a population?
Help please 1. Explain the difference between isotopes and biomarkers and how each can be used...
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1. Explain the difference between isotopes and biomarkers and how each can be used to identify characteristics of fossils. 2. Why do we see that each cell is only expressing a small fraction of the genes in it's genome at any given time? 3. Why can't natural selection alone drive dominant alleles to fixation within a population?
1. Fixation of Dominant Alleles Start with a population that has a gene with two alleles (A and a...
1. Fixation of Dominant Alleles Start with a population that has a gene with two alleles (A and a) with classical Mendelian dominance that are at equal frequency (p0.5. q 0.5). Assume this first generation is at hardy Weinberg equilibrium. Calculate the genotype frequencies AA- a. Aa b. Now assume some environmental change that makes the recessive phenotype completely unfit (fitness- 0). Calculate the allele frequencies and genotype frequencies in the second generation. (Hint: Your calculations might be easier if...
We expect natural selection and genetic drift to both result in the fixation of alleles, which...
We expect natural selection and genetic drift to both result in the fixation of alleles, which seems like it should reduce average heterozygocity in populations – there should be very little observed variation. However, we observe a tremendous amount of variation in populations. What can explain this observation?
Question 3: Explain why the fixation time of a beneficial, recessive allele is often much longer...
Question 3: Explain why the fixation time of a beneficial, recessive allele is often much longer than that of a beneficial, dominant allele. (2 points) Question 4: Name two types of natural selection that can maintain polymorphism. (2 points) Question 5: Consider an annual plant population in an environment with alternating dry and wet years. You observe the dry and wet years are equally frequent. At a locus with two alleles (A1 and A2), the relative fitnesses of the three...
QUESTION 18 Consider three cases of selection at a dialleic locus with alleles A1 and A2:...
QUESTION 18 Consider three cases of selection at a dialleic locus with alleles A1 and A2: Relative Fitnesses A2A2 A IAI A142 A2A2 - AIA A142 1242 AZAZ 1 0 .7 0.7 10.9 0.7 Initial Freq. of A1 -0.01; Generations - 500: Population size - Infinite. Al other conditions set to zero. Run the above model in the Alleel program Why does case 1 take so long to start to increase in frequency? Because natural selection can only act on...
Why can't evolution by natural selection explain the presence of the peacocks elaborate tail?
Why can't evolution by natural selection explain the presence of the peacocks elaborate tail?
7. Why do dominant alleles tend to be advantageous and recessive alleles tend to be disadvantageous...
7. Why do dominant alleles tend to be advantageous and recessive alleles tend to be disadvantageous in most populations? 8. You are studying a population of parrots and you observe that there are two alleles for wing color. Allele 1 codes for green wings and is dominant over allele 2, which codes for red wings. Allele 2 is at a frequency of 70% of the population, what should be the frequency of allele 1 homozygotes? 9. You are studying a...
Assume that a certain population is free of all evolutionary forces except for natural selection....
Assume that a certain population is free of all evolutionary forces except for natural selection. A particular recessive allele is known to confer a selective disadvantage when expressed in recessive homozygotes. In going from one generation to the next, the frequency of the dominant counterpart to this allele shifts from 0.2 to 0.3. 4. a. What is the selection coefficient for the homozygous recessive genotype? (4 points) b. What is the frequency of the dominant allele in generation 3? (4...
In the case of directional selection, if the advantageous allele (b) is recessive and a less...
In the case of directional selection, if the advantageous allele (b) is recessive and a less advantageous allele (B) is dominant: A. b will be lost in the population because the dominant allele will increase in frequency by natural selection B. b will increase in frequency at the same speed as if it was a dominant advantageous allele, because what matters is the coefficient of selection and not if the allele is dominant or recessive C. b will increase in...
help please Questions 1. The dominate alleles are and 2. The recessive alleles are _and 3....
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Questions 1. The dominate alleles are and 2. The recessive alleles are _and 3. The kernels on car "A" represents a _ 4. What were the genotypes of the parents for ear "A"? For the genotypes use the Capital letter lower case letter standard abbreviations to represent the dominant and recessive alleles (refer to above). 3. The kernels on ear "B" represents a _cross. 4. What were the genotypes of the parents for ear"B"? - X For the...
Help please
1. Explain the difference between isotopes and biomarkers and how each can be used to identify characteristics of fossils. 2. Why do we see that each cell is only expressing a small fraction of the genes in it's genome at any given time? 3. Why can't natural selection alone drive dominant alleles to fixation within a population?
1. Fixation of Dominant Alleles Start with a population that has a gene with two alleles (A and a) with classical Mendelian dominance that are at equal frequency (p0.5. q 0.5). Assume this first generation is at hardy Weinberg equilibrium. Calculate the genotype frequencies AA- a. Aa b. Now assume some environmental change that makes the recessive phenotype completely unfit (fitness- 0). Calculate the allele frequencies and genotype frequencies in the second generation. (Hint: Your calculations might be easier if...
QUESTION 18 Consider three cases of selection at a dialleic locus with alleles A1 and A2: Relative Fitnesses A2A2 A IAI A142 A2A2 - AIA A142 1242 AZAZ 1 0 .7 0.7 10.9 0.7 Initial Freq. of A1 -0.01; Generations - 500: Population size - Infinite. Al other conditions set to zero. Run the above model in the Alleel program Why does case 1 take so long to start to increase in frequency? Because natural selection can only act on...
Assume that a certain population is free of all evolutionary forces except for natural selection. A particular recessive allele is known to confer a selective disadvantage when expressed in recessive homozygotes. In going from one generation to the next, the frequency of the dominant counterpart to this allele shifts from 0.2 to 0.3. 4. a. What is the selection coefficient for the homozygous recessive genotype? (4 points) b. What is the frequency of the dominant allele in generation 3? (4...
help please
Questions 1. The dominate alleles are and 2. The recessive alleles are _and 3. The kernels on car "A" represents a _ 4. What were the genotypes of the parents for ear "A"? For the genotypes use the Capital letter lower case letter standard abbreviations to represent the dominant and recessive alleles (refer to above). 3. The kernels on ear "B" represents a _cross. 4. What were the genotypes of the parents for ear"B"? - X For the...
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