Campbell Biology in Focus (2nd Edition)
2nd Edition
ISBN: 9780321962751
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Jane B. Reece
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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WHAT IF? If the frequency of the CRallele were 0.6, predict the frequenciesof the CRCR, CRCW, and CWCW genotypes.
Q3) Why can we say that variations in human skin color are the result of natural selection in different environments? Why can we say that less pigmented skin is a result of conflicting selective factors? Answer in details(300 word)
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?
3.What type of selection would most likely benefit heterozygous individuals and which will result in a population losing alleles: directional, disruptive, or stabilizing? Explain.
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5.Describe the theory of evolution by natural selection. Include terms like "excess reproduction, genetically distinct offspring, changing allele frequencies, and adaptive traits".
Chapter 21 Solutions
Campbell Biology in Focus (2nd Edition)
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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- 1. 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_forwardQ1: What would the white-fur-pigment allele frequency be if three of the homozygous black allele mice (having two black alleles) were heterozygous (having one white and one black allele) instead? Q2: What would the white-fur-pigment allele frequency be if all of the white mice died and were therefore removed from the population? Would the black-fur-pigment allele frequency be affected? If so, how? Q3: What would the white-fur-pigment allele frequency be if all of the gray mice died and were therefore removed from the population?arrow_forwardWHAT IF? The increased fertility of the experimental hybrids could haveresulted from natural selection for thriving under laboratory conditions.Evaluate this alternative explanation for the result.arrow_forward
- Q1: What is natural selection selecting for here? Q2: Why do bacteria that are not genetically resistant to antibiotics die out when exposed to antibiotics? Q3: Why is the antibiotic represented by a kitchen strainer in this figure?arrow_forwardMAKE CONNECTIONS Explain how natural selection could increase the resemblance of a harmlessspecies to a distantly related harmful species. In addition to selection, what else could account for a harmlessspecies resembling a closely related harmful species? (See Concept 22.2.)arrow_forwardYou are studying gene Q/q in two populations of great white sharks. In one population most individuals have genotype QQ, and in the other population most individuals have the genotype qq. If there is some migration from each population into the other, how will this affect genotype frequencies?arrow_forward
- Kingma et al. (2011) found that in the purple-crowned fairy-wren, most subordinate helpers at the nest feed full siblings or half siblings, but some helpers are unrelated to the nestlings they assist. What Darwinian puzzle is created by these findings, and how might you solve the puzzle by using inclusive fitness theory? What predictions follow from the explanation(s) that you propose?arrow_forwardMAKE CONNECTIONS Balancing selection can maintain variation at a locus (see Concept 23.4). Based on theforaging experiments described in this chapter, devise asimple hypothesis to explain the presence of both for Rand forsalleles in natural fly populationsarrow_forwardWHAT IF? Consider two species that diverged whilegeographically separated but resumed contact beforereproductive isolation was complete. Predict the outcome over time if the two species mated indiscriminately and (a) hybrid offspring survived and reproducedmore poorly than offspring from intraspecific matingsor (b) hybrid offspring survived and reproduced as wellas offspring from intraspecific matings.arrow_forward
- 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.arrow_forwardWHAT IF? Is allopatric speciation more likely to occuron an island close to a mainland or on a more isolatedisland of the same size? Explain your prediction.arrow_forwardFollow up on the previous question, after reviewing your result, one of your classmates stated that this population is in Hardy-Weinberg equilibrium. You responded -Yea! I think you are right! -No! I don't think so, buddy! -I donâ t think we can tell anything from this study. -What the heck is Hardy-Weinberg equilibrium??!!arrow_forward
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