Biology: Life on Earth
10th Edition
ISBN: 9780321729712
Author: Gerald Audesirk, Teresa Audesirk, Bruce E. Byers
Publisher: Benjamin Cummings
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Chapter 15, Problem 3RQ
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At least one of the discoverers of this genetic equilibrium (Hardy) developed this HW equation to show that the dominant allele will not always take over the population just because that allele has a dominant effect on the phenotype. What additional factor would have to be present to cause a dominant allele to increase to a frequency of 100%? Why is this factor essential for the dominant allele to “take over” the gene pool?
If gene A/a is not in Hardy-Weinberg equilibrium due to natural selection such that individuals with the genotype AA have a fitness value of 1.0, heterozygotes have only slightly reduced fitness at 0.9, and individuals with the genotype aa have a fitness value of 0.6, what kind of change in allele frequency would you expect to see over time assuming you start with equal frequencies of the 2 alleles?
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a) Which colors in the genetic drift population would have better fitness in this new environment? Why/how?
b) Which of the colors would have less fitness? Why/how?
c) What would you expect to happen to the allele frequency for the following forms of the gene:
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Chapter 15 Solutions
Biology: Life on Earth
Ch. 15 - The ________ provides a simple mathematical model...Ch. 15 - 2. Different versions of the same gene are called...Ch. 15 - An organism's ________ refers to the specific...Ch. 15 - 4. A random form of evolution is called _________....Ch. 15 - Competition is most intense between members of...Ch. 15 - 6. The evolutionary fitness of an organism is...Ch. 15 - 1. What is a gene pool? How would you determine...Ch. 15 - 2. Define equilibrium population. Outline the...Ch. 15 - How does population size affect the likelihood of...Ch. 15 - If you measured the allele frequencies of a gene...
Ch. 15 - 5. People like to say that “you can’t prove a...Ch. 15 - 6. Describe the three ways in which natural...Ch. 15 - What is sexual selection? How is sexual selection...Ch. 15 - In North America, the average height of adult...Ch. 15 - Malaria is rare in North America. In populations...Ch. 15 - By the 1940s, the whooping crane population had...Ch. 15 - Prob. 4ACCh. 15 - A preview question for Chapter 16: A species is...
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- How Can We Measure Allele Frequencies in Populations? Drawing on your newly acquired understanding of the HardyWeinberg equilibrium law, point out why the following statement is erroneous: Because most of the people in Sweden have blond hair and blue eyes, the genes for blond hair and blue eyes must be dominant in that population.arrow_forwardHow Can We Measure Allele Frequencies in Populations? The MN blood group is a single-gene, two-allele system in which each allele is codominant. Why are such codominant alleles ideal for studies of allele frequencies in a population?arrow_forwardHow Can We Measure Allele Frequencies in Populations? In a population where the females have the allelic frequencies A = 0.35 and a = 0.65 and the frequencies for males are A = 0.1 and a = 0.9, how many generations will it take to reach HardyWeinberg equilibrium for both the allelic and the genotypic frequencies? Assume random mating and show the allelic and genotypic frequencies for each generation.arrow_forward
- What Causes Allele Frequencies to Change in Real Populations?arrow_forwardWhat does the Hardy-Weinberg model tell us about the factors that can change allele frequencies in populations and result in evolution? What are those factors, and what effect will they have on a biological population?arrow_forwardWhy is genetic drift more significant in small populations? Why does it take longer for genetic drift to cause allele fixation in large populations than in small ones?arrow_forward
- A recessive lethal allele has achieved a frequency of 0.22 due to genetic drift in a very small population. Based on natural selection, how would you expect the allele frequencies to change in the next three generations? (Note: Your calculation can assume that genetic drift is not altering allele frequencies in either direction.)arrow_forwardWhich type of selection (directional, disruptive, stabilizing) changes the overall average phenotype in a population? How does it do this? What does "additive” mean? Why aren't dominant and epistatic variances considered to be additive?arrow_forwardUnder the above conditions of reproductive discrimination against those with attached earlobes, if the population in this next generation is still 500,000 people, then the new genotypic frequencies will be: Homozygous dominants, unattached ear lobes: 0.34 Heterozygotes, unattached ear lobes: 0.48 Homozygous recessives, attached ear lobes: 0.18 What will be the allele frequencies for L and l in this generation? Did the frequency of the recessive allele (l), as compared to its frequency calculated in Part B, increase or decrease because of its deleterious effects on fitness? Does the possession of the recessive allele kill those who possess it? If those with attached ear lobes continue to be only half as successful in securing mates in each successive generation, what will happen to the frequency of the recessive allele in this population?arrow_forward
- Describe how the phenotype of individuals with sickle-cell disease influences how common the HbS allele is in the population: Do individuals with sickle-cell disease typically have many offspring? What effect does the fact that individuals with sickle-cell disease do not produce many offspring have on the frequency of the HbS allele in the population over time? Given this, do you expect the HbS allele to be common or rare in populations?arrow_forwardA population with allele frequencies p=0.6 and q=0.4 is subjected to selection against the dominant allele. If selection is completely effective (W11=0, W12=0, W22=1), what will be the frequency of the dominant allele in the next generation?arrow_forwardWhat is the number of dominant alleles in a population of 100 ladybugs with the following genotypes for wing spots (B): 30 BB, 60 Bb, 10 bb? What is the frequency of the recessive allele? Group of answer choices 160, 0.45 120, 0.4 90, 0.6 10, 0.3 60, 0.2arrow_forward
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