Questions and Answers
What is the definition of gene flow?
What effect does gene flow have within a population?
How does gene flow affect distant populations?
Would sedentary organisms have a higher or lower rate of gene flow?
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What is non-random mating?
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Which statement is true regarding non-random mating and humans?
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How does non-random mating work against natural selection?
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Which of the following correctly describes the effect of gene flow on evolution?
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What is the primary effect of gene flow on genetic variation in a population?
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Which statement about natural selection and non-random mating is accurate?
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Study Notes
Agents of Evolutionary Change
- There are five agents of evolutionary change: mutation, genetic drift, gene flow, non-random mating, and natural selection.
Mutation
- A mutation is a change to the nucleotide sequence in an organism's genetic material that occurs due to errors in DNA replication, exposure to UV or radiation, mutagens, and/or viruses.
- Mutations create variation in gene pools and can be either favorable or unfavorable depending on the type of mutation and the environment.
- Most mutations are minor and do not impact an organism's fitness, and many are repaired by cells before they become permanent.
- Mutations provide new traits for natural selection to act upon.
The Peppered Moth
- The peppered moth evolved in response to pollution during the Industrial Revolution in England, resulting in a shift from light-colored to dark-colored moths.
- As environmental standards improved, light-colored moths became common again, but the genetic change remained.
Natural Selection
- Natural selection is the process by which environmentally favorable genetic traits become more common in a population, while unfavorable traits become less common.
- It acts on the observable characteristics of an organism, favoring those with advantageous traits.
- Organisms with favorable traits are more likely to survive and reproduce, passing on those traits to their offspring.
Genetic Drift
- Genetic drift is the random variation in which organisms reproduce, leading to changes in a population's genetic makeup over time.
- It depends on a small population size, which increases the chance for change to occur permanently.
- In larger populations, there is a normalizing effect that counteracts genetic drift.
Analogy of Genetic Drift
- Imagine a population represented by a jar of marbles, where the colors correspond to different gene outcomes.
- Randomly selecting and replacing marbles represents the random reproduction of organisms.
- Over time, the marble population may change due to chance, resulting in the loss of one color (gene outcome).
The Finches of Galapagos
- The finches discovered by Darwin on the Galapagos archipelago are an example of natural selection.
- Each finch species has a beak adapted to its specific food source, resulting from genetic variations and environmental selection.
Gene Flow
- Gene flow is the movement of genes from one population to another, increasing genetic variation in the receiving population.
- It can occur within a population, introducing new genes, or across populations, making them genetically similar and reducing speciation.
Non-Random Mating
- Non-random mating is the selection of mates based on specific traits, not by chance.
- It occurs in humans, where people select mates based on appearance, cultural values, social rules, stature, or personality.
- Non-random mating works against natural selection, as it is not only the environment selecting for certain traits.
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Description
This quiz covers the five agents of evolutionary change, including mutation, genetic drift, gene flow, non-random mating, and natural selection. Learn about the mechanisms that drive evolution.