Podcast
Questions and Answers
Which type of selection tends to increase genetic variation?
Which type of selection tends to increase genetic variation?
- Stabilizing selection
- Natural selection
- Directional selection
- Disruptive selection (correct)
Disruptive selection eliminates phenotypes near the ____ and favors the _____ phenotypes, resulting in ____ in a population.
Disruptive selection eliminates phenotypes near the ____ and favors the _____ phenotypes, resulting in ____ in a population.
average; extreme; increased genetic variation
In a bell-shaped curve, the x-axis of the graph represents which of the following?
In a bell-shaped curve, the x-axis of the graph represents which of the following?
- Frequency of traits
- The value of a particular characteristic (correct)
- The average of the traits
- None of the above
Heterozygote advantage leads to less genetic variation in the population.
Heterozygote advantage leads to less genetic variation in the population.
Which kind of selection appears to have made giraffes long-necked?
Which kind of selection appears to have made giraffes long-necked?
Directional selection drives the average of the population _____
Directional selection drives the average of the population _____
Which kind of selection is most likely at work regarding the birth weight of babies?
Which kind of selection is most likely at work regarding the birth weight of babies?
Stabilizing selection causes _____; ____ phenotypes become less common.
Stabilizing selection causes _____; ____ phenotypes become less common.
Which kind of selection acts on beak size in black-bellied seedcrackers?
Which kind of selection acts on beak size in black-bellied seedcrackers?
Disruptive selection causes ____ to be favored over the intermediate phenotypes.
Disruptive selection causes ____ to be favored over the intermediate phenotypes.
Which kind of selection acts on the adult body size of Aristelliger lizards?
Which kind of selection acts on the adult body size of Aristelliger lizards?
Allele frequencies measure _____
Allele frequencies measure _____
By looking at how allele frequencies change over time, ____
By looking at how allele frequencies change over time, ____
Consistently causes a population to become better adapted to its environment
Consistently causes a population to become better adapted to its environment
Cannot cause a harmful allele to become more common
Cannot cause a harmful allele to become more common
A result of differential success in reproduction
A result of differential success in reproduction
Responsible for the founder effect
Responsible for the founder effect
Causes allele frequencies to fluctuate randomly
Causes allele frequencies to fluctuate randomly
Responsible for the bottleneck effect
Responsible for the bottleneck effect
A result of the movement of fertile individuals or their gametes
A result of the movement of fertile individuals or their gametes
Can introduce new alleles into a population's gene pool
Can introduce new alleles into a population's gene pool
Natural selection is the result of ____
Natural selection is the result of ____
Natural selection is the only mechanism of evolution that ____
Natural selection is the only mechanism of evolution that ____
Genetic drift describes evolution due to _____ and causes _____ fluctuations in allele frequencies.
Genetic drift describes evolution due to _____ and causes _____ fluctuations in allele frequencies.
Genetic drift can have a _____ effect in a small population
Genetic drift can have a _____ effect in a small population
Gene flow results when _____.
Gene flow results when _____.
Gene flow can bring new alleles that are ____, ____, or ___ into a population
Gene flow can bring new alleles that are ____, ____, or ___ into a population
During an extreme heat wave, plants with white flowers survive better. Mechanism? Effect on allele frequencies?
During an extreme heat wave, plants with white flowers survive better. Mechanism? Effect on allele frequencies?
A person uproots the five closest plants, which all happen to have white flowers. Mechanism? Effect on allele frequencies?
A person uproots the five closest plants, which all happen to have white flowers. Mechanism? Effect on allele frequencies?
A storm kills many plants at random. Mechanism? Effect on allele frequencies?
A storm kills many plants at random. Mechanism? Effect on allele frequencies?
Plants with purple flowers attract more insects, which pollinate the plants. Mechanism? Effect on allele frequencies?
Plants with purple flowers attract more insects, which pollinate the plants. Mechanism? Effect on allele frequencies?
Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat. Mechanism? Effect on allele frequencies?
Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat. Mechanism? Effect on allele frequencies?
Different events and conditions result in _____, _____, and ____
Different events and conditions result in _____, _____, and ____
Natural selection, genetic drift, and gene flow cause _____ in different ways
Natural selection, genetic drift, and gene flow cause _____ in different ways
_____, which results from differential survival and reproduction, is the only mechanism of evolution that consistently causes a population to become better adapted to its environment.
_____, which results from differential survival and reproduction, is the only mechanism of evolution that consistently causes a population to become better adapted to its environment.
_____ and _____ cause alleles to increase in frequency regardless of whether they are harmful, neutral, or beneficial, _____ causes only beneficial alleles to become more common in a population.
_____ and _____ cause alleles to increase in frequency regardless of whether they are harmful, neutral, or beneficial, _____ causes only beneficial alleles to become more common in a population.
Study Notes
Selection Types and Genetic Variation
- Disruptive selection increases genetic variation by favoring extreme phenotypes while eliminating average ones.
- Directional selection alters the average phenotype in a population by pushing it in a specified direction, as seen in giraffes with long necks.
- Stabilizing selection maintains the average phenotype while reducing the frequency of extreme phenotypes, such as birth weights leading to complications with very large or small babies.
Phenotype Influence and Traits
- In bell-shaped curves, the x-axis represents the range of a specific characteristic, such as size or color.
- Black-bellied seedcrackers exhibit disruptive selection in beak size, as they have adapted to eat either soft or hard seeds.
Genetic Concepts
- Heterozygote advantage provides better fitness for heterozygous individuals, resulting in increased genetic variation contrary to the notion that it reduces variation.
- Allele frequencies indicate the proportion of different alleles within a population, essential for studying evolution over time.
Evolutionary Mechanisms
- Natural selection is driven by differential survival and reproduction, consistently enhancing a population's adaptation to its environment.
- Genetic drift randomly affects allele frequencies, causing significant effects in small populations due to chance events.
- Gene flow introduces new alleles into a population, which can be beneficial, harmful, or neutral, affecting genetic diversity.
Mechanisms and Allele Frequency Changes
- During natural selection, plants with advantageous traits (e.g., white flowers during a heat wave) have allele frequencies that increase in their favor.
- Genetic drift can lead to increased frequencies of specific alleles through chance events, such as uprooting plants or random storms affecting populations unpredictably.
- Different events, like purposeful removal of plants or accidental introductions of seeds, demonstrate how genetic drift and gene flow can unpredictably change allele frequencies.
Summarizing Change in Evolution
- Natural selection, genetic drift, and gene flow are mechanisms that contribute to changes in allele frequencies and population evolution in distinct ways.
- Only natural selection effectively leads to adaptation, while genetic drift and gene flow may increase allele frequencies without consideration of their effects on fitness.
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Description
This quiz focuses on concepts related to selection in genetics, particularly disruptive selection. Test your understanding of how this type of selection influences genetic variation and its representation on graphs. Ideal for biology students wishing to master these concepts.
