Textbook Question
Describe how natural selection can produce balanced polymorphism of allele frequencies through selection that favors heterozygotes.
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Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
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Sanders 3rd EditionCh. 20 - Population Genetics and Evolution at the Population, Species, and Molecular LevelsProblem 7
Sanders 3rd EditionCh. 20 - Population Genetics and Evolution at the Population, Species, and Molecular LevelsProblem 7Chapter 20, Problem 7
Over the course of many generations in a small population, what effect does random genetic drift have on allele frequencies?
Verified step by step guidance1
Understand that genetic drift is a mechanism of evolution that refers to random changes in the frequency of alleles in a population.
Recognize that in small populations, genetic drift has a more pronounced effect because random events can lead to significant changes in allele frequencies from one generation to the next.
Consider that over many generations, genetic drift can lead to the fixation or loss of alleles, meaning that an allele can become the only allele present in the population or be completely lost.
Acknowledge that genetic drift can reduce genetic variation within a population, as alleles are lost or fixed over time.
Note that genetic drift can lead to different populations diverging genetically from each other, especially if they are isolated, as random changes in allele frequencies accumulate over generations.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Random Genetic Drift
Random genetic drift is a mechanism of evolution that refers to random fluctuations in allele frequencies within a population due to chance events. In small populations, these random changes can lead to significant shifts in genetic variation over generations, potentially resulting in the loss of alleles or fixation of certain alleles, regardless of their adaptive value.
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Allele Frequencies
Allele frequencies represent the proportion of different alleles of a gene in a population. They are crucial for understanding genetic diversity and evolution, as changes in these frequencies can indicate how populations evolve over time. In the context of random genetic drift, allele frequencies can change unpredictably, leading to reduced genetic variation.
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Population Size and Genetic Drift
The size of a population significantly influences the impact of random genetic drift. In smaller populations, the effects of drift are more pronounced, leading to greater fluctuations in allele frequencies. This can result in rapid evolutionary changes, whereas larger populations tend to buffer against such random changes, maintaining more stable allele frequencies over time.
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Related Practice
Textbook Question
Thinking creatively about evolutionary mechanisms, identify at least two schemes that could generate allelic polymorphism in a population. Do not include the processes described in the answer to Problem 4.
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Textbook Question
Genetic drift, an evolutionary process affecting all populations, can have a significant effect in small populations, even though its effect is negligible in large populations. Explain why this is the case.
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Textbook Question
Catastrophic events such as loss of habitat, famine, or overhunting can push species to the brink of extinction and result in a genetic bottleneck. What happens to allele frequencies in a species that experiences a near-extinction event, and what is expected to happen to allele frequencies if the species recovers from near extinction?
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Textbook Question
George Udny Yule was wrong in suggesting that an autosomal dominant trait like brachydactyly will increase in frequency in populations. Explain why Yule was incorrect.
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Textbook Question
The ability to taste the bitter compound phenylthiocarbamide (PTC) is an autosomal dominant trait. The inability to taste PTC is a recessive condition. In a sample of 500 people, 360 have the ability to taste PTC and 140 do not. Calculate the frequency of the recessive allele.
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