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Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
Chapter 20, Problem 3

Identify and describe the evolutionary forces that can cause allele frequencies to change from one generation to the next.

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1
Understand that evolutionary forces are mechanisms that cause changes in allele frequencies within a population over generations, leading to evolution.
Identify the main evolutionary forces: natural selection, genetic drift, gene flow (migration), mutation, and non-random mating.
Describe natural selection as the process where alleles that confer a survival or reproductive advantage increase in frequency because individuals with those alleles are more likely to survive and reproduce.
Explain genetic drift as random fluctuations in allele frequencies due to chance events, which are especially significant in small populations.
Discuss gene flow as the movement of alleles between populations through migration, which can introduce new alleles or change allele frequencies in a population.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Natural Selection

Natural selection is the process where individuals with advantageous traits have higher survival and reproduction rates, causing those alleles to increase in frequency over generations. It drives adaptation by favoring beneficial genetic variations in a population.
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Genetic Drift

Genetic drift refers to random changes in allele frequencies due to chance events, especially in small populations. It can lead to the loss or fixation of alleles independently of their selective advantage, reducing genetic variation over time.
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Gene Flow

Gene flow is the movement of alleles between populations through migration or interbreeding. It introduces new genetic material, which can alter allele frequencies and increase genetic diversity within a population.
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