Genetic Analysis: An Integrated Approach (2nd Edition)
2nd Edition
ISBN: 9780321948908
Author: Mark F. Sanders, John L. Bowman
Publisher: PEARSON
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Chapter 22, Problem 14P
Directional selection presents an apparent paradox. By favoring one allele and disfavoring others, directional selection can lead to fixation (a frequency of
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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?
you (should have) learned that selection alone cannot purge a population of the very last copy of a deleterious allele. If selection is unable to do so, which of the remaining mechanisms (of the five Hardy-Weinberg) assumptions is MOST LIKELY to do so? Justify your answer. That is, why is the mechanism you picked the most likely to get rid of that last copy of a harmful allele?
The trait that natural selection “selects for” is lifetime Darwinian fitness. If relative matching of the moths to the background is determining fitness differences, is there any difference in other fitness components in the color morphs of Biston betularia that is influencing the direction of evolution in the three populations shown in the graph?
Chapter 22 Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
Ch. 22 - 20.1 Compare and contrast the terms in each of the...Ch. 22 - In a population, what is the consequence of...Ch. 22 - 20.3 Identify and describe the evolutionary forces...Ch. 22 - Describe how natural selection can produce...Ch. 22 - Thinking creatively about evolutionary mechanisms,...Ch. 22 - 20.6 Genetic drift, an evolutionary process...Ch. 22 - Over the course of many generations in a small...Ch. 22 - Catastrophic events such as loss of habitat,...Ch. 22 - 20.9 George Udny Yule was wrong in suggesting that...Ch. 22 - 20.10 The ability to taste the bitter compound...
Ch. 22 - Figure 20.6 illustrates the effect of an ethanol ...Ch. 22 - 20.12 Biologists have proposed that the use of...Ch. 22 - 20.13 Two populations of deer, one of them large...Ch. 22 - 20.14 Directional selection presents an apparent...Ch. 22 - 20.15 What is inbreeding depression? Why is...Ch. 22 - 20.16 Certain animal species, such as the...Ch. 22 - Genetic Analysis 20.1 predicts the number of...Ch. 22 - 20.18 In a population of rabbits, and . The...Ch. 22 - Sickle cell disease (SCD) is found in numerous...Ch. 22 - 20.20 Epidemiologic data on the population in the...Ch. 22 - The frequency of tasters and nontasters of PTC...Ch. 22 - Tay-Sachs disease is an autosomal recessive...Ch. 22 - 20.23 Cystic fibrosis (CF) is the most common...Ch. 22 - 20.24 In the mouse, Mus musculus, survival in...Ch. 22 - 20.25 In a population of flowers growing in a...Ch. 22 - Assume that the flower population described in the...Ch. 22 - 20.27 ABO blood type is examined in a Taiwanese...Ch. 22 - 20.28 A total ofmembers of a Central American...Ch. 22 - 20.29 A sample offield mice contains individuals...Ch. 22 - Prob. 30PCh. 22 - Albinism, an autosomal recessive trait...Ch. 22 - Prob. 32PCh. 22 - 20.33 Evaluate the following pedigree, and answer...Ch. 22 - Evaluate the following pedigree, and answer the...Ch. 22 - The following is a partial pedigree of the British...Ch. 22 - Draw a separate hypothetical pedigree identifying...Ch. 22 - Prob. 37PCh. 22 - 20.38 Achromatopsia is a rare autosomal recessive...Ch. 22 - 20.39 New allopolyploid plant species can arise by...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Much attention is given to the existence of genetic variation in populations.Why do evolutionary biologists give so much attention to this? Explain mechanisms thatgenerate genetic variation in populations. Explain mechanisms that maintain geneticvariation in populations. Provide examples and dataarrow_forwardIt is a common but mistaken belief that because some allele are dominant and others are recessive, the dominants will eventually replace all the recessives in a population. How does the Hardy-Weinberg equilibrium refute this notion?arrow_forwardWhy is population level genetic variation important for evolution and what causes genetic variation ? How do we detect if evolution is occurring ?arrow_forward
- What 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_forwardMechanisms for the persistence of genetic variation in a population include:i) antagonistic selection, ii) overdominance, iii) heterosis, iv) inverse-frequency-dependent selection, and v) mutation-selection balance. Describe how mutation-selection balance can act to maintain genetic variation in a population.arrow_forwardIn a hypothetical population which is in Hardy Weinberg equilibrium, the frequency for a recessive allele is 20%. What percentage of the population would be expected to show the dominant trait in the next generation?arrow_forward
- Is it likely that the selection coefficient (s) is similar in value for the three populations shown? Is it important to know if the amount of genetic variation for the trait under selection is approximately equal in all three populations in the graph? Why or why not?arrow_forwardWhat are two reasons why a selection limit is reached in which artificial selection no longer has an effect?arrow_forwardYou discover that there are 4 alleles for the “w” gene that determines wing shape in flies. Is this a violation of Hardy-Weinberg model? Group of answer choices Not if one of the alleles is present only in females. Not if the trait is determined by sexual selection. Not if all four alleles are present in the population. Yes, because Hardy-Weinberg can only be applied to genes with 2 alleles. None of the answers shown are correct.arrow_forward
- An hypothesis for the extinction of the dinosaurs is that the earth had been hit by a gigantic meteor that caused the death of those big reptiles. In that case the entire genetic pool of those animals has been destroyed, invalidating the Hardy-Weinberg equilibrium. In Genetics what is this type of gene frequency change called?arrow_forwardWhich of these scenarios is an example of disruptive selection? Darker colored morphs in a butterfly population are more adaptive than lighter colored morphs, and lighter colored morphs are eliminated from the population. Intermediate gray morphs of a butterfly population are maintained, and the extreme dark and light color morphs have been eliminated. The dark and light color morphs of a butterfly population are maintained, and the intermediate gray morph has been eliminated from the population. A new, unique color form arises from a mutation in a population of butterflies.arrow_forwardUnder 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)?arrow_forward
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