CAMPBELL MASTERING BIOLOGY ACCESS>I<
18th Edition
ISBN: 9781323766286
Author: Pearson
Publisher: PEARSON
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Chapter 21.4, Problem 3CC
Summary Introduction
To determine:
The type of natural selection (directional, disruptive or stabilizing) in situation where heterozygotes for a certain locus in a population have extreme phenotype that confers a selective advantage.
Introduction:
Natural selection is processes by which organisms are tend to adapt the environment and produce more offsprings of particular traits. Natural selection: are of 3 types (a) stabilizing selection; in which an average phenotype is favored, (b) directional selection; in which the change in the environment change the wide range of
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1.Describe the ways that gene number or gene position on a chromosome, might be altered? What implications might that have on evolution?
2.What are the conditions that must be met for a population to stay in Hardy-Weinberg equilibrium? What happens if these conditions are not met?
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Mechanisms 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.
Chapter 21 Solutions
CAMPBELL MASTERING BIOLOGY ACCESS>I<
Ch. 21.1 - Explain why genetic variation within a population...Ch. 21.1 - Of all the mutations that occur in a population,...Ch. 21.1 - Prob. 3CCCh. 21.2 - A population has 700 individuals, 85 of genotype...Ch. 21.2 - The frequency of allele a is 0.45 for a population...Ch. 21.2 - WHAT IF? A locus that affects susceptibility to a...Ch. 21.3 - In what sense is natural selection more...Ch. 21.3 - Distinguish genetic drift from gene flow in terms...Ch. 21.3 - WHAT IF? Suppose two plant populations exchange...Ch. 21.4 - What is the relative fitness of a sterile mule?...
Ch. 21.4 - Explain why natural selection is the only...Ch. 21.4 - Prob. 3CCCh. 21 - Natural selection changes allele frequencies...Ch. 21 - No two people are genetically identical, except...Ch. 21 - Sparrows With average-sized w1ngs survive severe...Ch. 21 - If the nucleotide variability of a locus equals...Ch. 21 - There are 25 individuals in population 1, all with...Ch. 21 - A fruit fly population has a gene with two...Ch. 21 - FOCUS ON EVOLUTION Using at least TWO examples,...Ch. 21 - Prob. 9TYUCh. 21 - SYNTHESIZE YOUR KNOWLEDGE This kettle lake formed...
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- Explain the difference between Disruptive Selection & Directional Selection ?arrow_forwardWhat are two reasons why a selection limit is reached in which artificial selection no longer has an effect?arrow_forwardDescribe the competing selective forces acting on peacock tails. Together, do these selective forces produce disruptive, directional, or stabilizing selection?arrow_forward
- 1.) What happens to the genotypic frequencies from generation 1 to generation 5? 2.) What process is occurring when there is a change in genotypic frequencies over a long period of time? 3.) What would happen if it were more advantageous to be heterozygous (Ff)? Would there still be homozygous fish? Explain. 4.) What happens to the recessive genes over successive generations? Explain. 5.) Why doesn't the recessive gene disappear from the population?arrow_forwardWhich of the following mechanism(s) will lead to a decrease in heterozygosity? Select all that apply. Multiple correct - genetic drift - migration - positive assortative mating - mutation - negative assortative mating I tried genetic drift, negative assortative mating and mutation - that was incorrect I also tried genetic drift and negative assortative mating - that was also incorrect Lastly, I tried positive assotative mating, genetic drift and migration - that was also incorrectarrow_forward1. Which parameter from the software you are using in lab this week must you adjust in order to decrease the population size of the organisms in the simulation? 2. Which parameter from the software you are using in lab this week must you adjust in order to change the frequency of the A2 allele in the simulation? 3. If you wanted to simulate a population that experiences no natural selection pressures in AlleleA1, you would:arrow_forward
- Which 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_forwardSuppose that a population is at equilibrium between mutation and selection for a deleterious recessive allele, where s = 0.5 and μ = 10−5. What is the equilibrium frequency of the allele? What is the selection cost?arrow_forwardImagine a population in which the survival of A1A1 homozygotes is 80 percent as great as that of A1A2 heterozygotes, while the survival of A2A2 homozygotes is 95 percent that of the heterozygotes. What is p, the frequency of the A2 allele, at equilibrium? Now suppose the population has reached this equilibrium, but that the environment then changes so that the relative fitnesses of A1A1, A1A2, and A2A2 become 1.0, 0.95, and 0.90. What will p be in the adults after one generation of selection in the new environment?arrow_forward
- Natural selection occurs only if there is both (1) variation in the genetic information between organisms in a population and (2) variation in the expression of that genetic information—that is, trait variation—that leads to differences in performance among individuals. What kind of variation might exist in bioluminescing organisms, and what differences in performance might result? (Remember, evolution is a consequence of the interaction of four factors: (1) the potential for a species to increase in number, (2) the genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for an environment’s limited supply of the resources that individuals need in order to survive and reproduce, and (4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment.)arrow_forwardThe ratio of nonsynonymous differences pernonsynonymous site, dN, to synonymous differences per synonymous site, dS, can be usedto test for positive selection Imagine that in a duplicate pair of loci, oneparalog is evolving neutrally while the other isevolving under strong positive selection. Whatspecific data are needed to detect that situationusing the dN/dS ratio, and what pattern do youexpect to see?arrow_forwardHeritability is valid for (select all that apply)? a-No answer text provided. b-No answer text provided. c-Multiple populations of a species d-Single populations of a species e-Any environment f-Any point in time g-A specific point in timearrow_forward
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