Campbell Biology In Focus, Loose-leaf Edition (3rd Edition)
3rd Edition
ISBN: 9780134895727
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky
Publisher: PEARSON
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Textbook Question
Chapter 21, Problem 4TYU
There are 25 individuals in population 1, all with genotype A.A. and there are 40 individuals in population 2, all with genotype aa Assume that these populations are located far from each other and that their environmental conditions are very similar. Based on the information given here, the observed
- A. genetic drift.
- B. gene flow.
- C. nonrandom mating.
- D. directional selection.
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All of the following are causes for evolutionary concern in small populations, EXCEPT:
a.
Unmasking of deleterious alleles.
b.
Natural selection can be overwhelmed by drift, and thus cannot counterbalance the effects.
c.
Random fixation of deleterious alleles is more likely to occur in small populations.
d.
Homozygosity decreases more rapidly in smaller populations compared to larger populations.
A population of gophers is very isolated, so no individuals can move in/out of the population. It is very small, so random events affect allele frequencies and many traits are under strong selection. Males are chosen randomly. Which statement is correct?
A. Allele frequencies in 10 generations will be different than they are today.
B. Individual gophers are evolving traits they need to survive
C.Genetic drift is not acting on the gophers
D. The population is in Hardy-Weinberg equilibrium
With regard to genetic drift, are the following statements true or false? If a statement is false, explain why.
A. Over the long run, genetic drift leads to allele fixation or loss.
B. When a new mutation occurs within a population, genetic drift is more likely to cause the loss of the new allele rather than the fixation of the new allele.
C. Genetic drift promotes genetic diversity in large populations.
D. Genetic drift is more significant in small populations.
Chapter 21 Solutions
Campbell Biology In Focus, Loose-leaf Edition (3rd 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 - Consider a population in which heterozygotes at a...Ch. 21 - Natural selection changes allele frequencies...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. 8TYUCh. 21 - SYNTHESIZE YOUR KNOWLEDGE This kettle lake formed...
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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
- A hypothetical population was found to have a genotype frequency of AA=20%, Aa=40%, aa=40%. If the “A” allele determines the larger beak depth of this species (“AA” leads to large beak depth, “Aa” is moderate beak depth, and “aa” leads to smaller beak depth), what type of selection is this trait likely experiencing in this population? a. stabilizing b. directional c. disruptive d. none of the abovearrow_forwardYou are examining population genetics of aquatic iguanas that live on the Galapagos islands. When you go to visit, you notice that the iguanas can easily swim to close neighboring islands but would have swim very long distances to reach further islands. Which of the following statements is a likely conclusion from your research? a. Populations are less similar the closer the islands are to each other. b. The further the islands likely have the greatest genetic diversity. c. Larger islands always have the lowest heterozygosity. d. Smaller populations on very small islands exhibit greater population differentiation.arrow_forwardA population occupies heterogeneous environments in which the fitness of some genotypes is higher in one environment and the fitness of other individuals is higher in another environment. This situation is likely to result in a. directional selection. b. stabilizing selection. c. disruptive selection. d. balancing selection.arrow_forward
- Which of the following statements most accurately describes the effects of genetic drift on a population? a. Populations of the same size will follow the same evolutionary trajectory when evolving due to drift. b. Genetic drift has the potential to drive evolution in all populations. c. Allele frequencies in a population of infinite size will ultimately drift to fixation or loss. d. The loss of otters in California due to excessive hunting cause a founder effect.arrow_forwardHardy Weinberg equilibrium (HWE) describes a situation in which the relative frequencies of alleles do not change over generations. which of the following could prevent HWE from being maintained? A. New mutations B. All individuals reproducing equally C. Random mating D. No individuals entering the populationarrow_forwardSickle cell anemia is maintained in human populations because individuals with a single copy of the sickle cell allele have resistance to malaria but lack the health problems of individuals with two copies of the allele. Variation at the sickle cell locus is maintained by which of the following? Group of answer choices A. heterozygote advantage B. random change in allele frequency C. mutation selection balance D. frequency dependent selectionarrow_forward
- Migration of individuals from a mainland population to a unique island population will result in… a. homogenization of allele frequencies between the two populations. b. isolation and bottleneck effect. c. increased homozygosity in both populations. d. increased population differentiation between the two populations.arrow_forwardA new species of snail was discovered. Your initial population genetics survey found that fA:0.48. To determine the primary mode of reproduction you survey the population again in one generation. You collect 100 individuals in the next generation. The composition of your collection is AA=38, Aa=20, aa=42. What is the primary mode of reproduction? a. random mating b. not enough information to determine c. nonrandom mating due to inbreedingarrow_forwardWithin a particular population, darkly colored rats are more likely to survive than more lightly colored individuals. This situation is likely to result in a. directional selection. b. stabilizing selection. c. disruptive selection. d. balancing selection.arrow_forward
- Which of the following statements describes an example of genetic drift?a. Allele g for fat production increases in a small population because birds with more bodyfat have higher survivorship in a harsh winter.b. Random mutation increases the frequency of allele A in one population but not inanother.c. Allele R reaches a frequency of 1.0 because individuals with genotype rr are sterile.d. Allele m is lost when a virus kills all but a few individuals and just by chance, none ofthe survivors possess allele m.arrow_forwardScientists have concluded that the AS genotype as an adaptation for survival in Africa. Support the conclusion in terms of natural selection A. The frequency of the AS allele increases proportionately to the number of Africans in the population B. Because Malaria does not exist in the U.S and the AS allele does not provide any advantage to survival there. C. As the frequency of Malaria increases so does the frequency of the AS allele combination as it protects against getting Malaria D. Those without the AS genotype die out due to sickle cell disease; the populations left with a greater allelic frequency of the AS genotypearrow_forwardWhich of the following is NOT a correct statement regarding the neutral-mutation explanation for the high levels of genetic variation? A. Most genetic variation observed is adaptively neutral. B. Natural selection plays a lesser role in maintaining genetic variation. C. When natural selection occurs it leads to a decrease in genetic variation. D. Genetic variation is maintained mainly via the random effects of genetic drift.arrow_forward
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