Define allele frequency .

Allele frequency is how common an allele is within a population's gene pool .

Besides natural selection, what three random processes can change allele frequencies in a population?

Mutation Genetic drift Migration

Mutation is a random process that adds new genetic to a population when it generates new alleles.

Mutation is a random process that adds new genetic variation to a population when it generates new alleles.

True or False? A mutation occurring in a somatic (body) cell will be passed on to the next generation and can drive natural selection.

False. Only mutations in gametes can be inherited; a somatic mutation is not passed on to offspring, so it has no impact on natural selection.

How does natural selection act on the new alleles produced by mutation?

An advantageous allele is more likely to be passed on , as it increases the chance of survival and reproduction, while a disadvantageous allele is less likely to be passed on .

Define genetic drift .

Genetic drift is a non-selective process that occurs when chance events influence the passing on of alleles to the next generation, leading to changes in allele frequencies.

Why are small populations more susceptible to genetic drift than large ones?

Random events cause proportionally larger changes in allele frequencies when there are fewer individuals , so chance can shift frequencies quickly in a small population.

Define bottleneck effect .

Bottleneck effect is a type of genetic drift in which a large population undergoes a dramatic reduction in size , for at least one generation, leading to a loss of genetic diversity .

Define founder effect .

Founder effect is a type of genetic drift in which a small group of individuals separates from a larger population to establish a new one, resulting in reduced genetic diversity .

True or False? Genetic drift can cause a small population to diverge genetically from other populations of the same species, even without selective pressures.

True. Because chance has a large effect in small populations , allele frequencies can shift enough for the population to diverge without any natural selection.

Gene flow is the addition or removal of alleles from a population, which can result from the migration of individuals between populations.

Gene flow between two populations prevents them from into separate species.

Gene flow between two populations prevents them from diverging into separate species.

How does gene flow counteract the effects of natural selection and genetic drift between two populations?

The mixing of their gene pools prevents any accumulation of genetic differences between the populations, stopping them from diverging.

Define Hardy-Weinberg principle .

The Hardy-Weinberg principle is a model stating that, if certain conditions are met, the allele frequencies of a gene in a population will not change from one generation to the next.

What are the five conditions that must be met for a population to be in Hardy-Weinberg equilibrium?

A large population size No migration into or out of the population No new mutations Random mating No natural selection

True or False? The conditions for Hardy-Weinberg equilibrium are commonly all met in natural populations.

False. The conditions are very rarely, if ever, all met in nature, but they provide a useful null hypothesis for evaluating whether evolution is occurring.

A population that is in Hardy-Weinberg equilibrium is described as , meaning its allele frequencies are not changing.

A population that is in Hardy-Weinberg equilibrium is described as non-evolving , meaning its allele frequencies are not changing.

What does the Hardy-Weinberg equation allow you to calculate and predict?

It allows the calculation of allele and genotype frequencies within a population, and predictions about how these frequencies will change in future generations.

Define allele frequency .

Allele frequency is the proportion of a particular allele among all copies of that gene in a population, expressed as a value between 0 and 1.

In the Hardy-Weinberg equation, what do the letters p and q represent?

p is the frequency of the dominant allele q is the frequency of the recessive allele

Because there are only two alleles for the gene, their frequencies add up to give the equation p + q = .

Because there are only two alleles for the gene, their frequencies add up to give the equation p + q = 1 .

What is the full Hardy-Weinberg equation relating the three genotype frequencies?

p 2 + 2*pq + q ^ 2 ^ = 1 * p 2 = frequency of the homozygous dominant genotype 2*pq = frequency of the heterozygous * genotype q 2 = frequency of the homozygous recessive genotype

In the Hardy-Weinberg equation, the term represents the frequency of the heterozygous genotype.

In the Hardy-Weinberg equation, the term 2*pq * represents the frequency of the heterozygous genotype.

When solving a Hardy-Weinberg problem, why should you always start with the recessive phenotype?

The recessive phenotype is the only phenotype whose genotype is known immediately, because it must be homozygous recessive ( q 2 ). This lets you find q , then p , and finally all genotype frequencies.

True or False? A change in the allele frequencies of a population over successive generations provides evidence that evolution is occurring.

True. Stable allele frequencies indicate Hardy-Weinberg equilibrium, so changing allele frequencies show the population is evolving .

AP®BiologyCollege BoardFlashcardsUnit 7: Natural SelectionPopulation Genetics

Population Genetics (College Board AP® Biology): Flashcards

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FrontGenetic Change in Populations
Define allele frequency.
FrontGenetic Change in Populations
Besides natural selection, what three random processes can change allele frequencies in a population?
BackGenetic Change in Populations
Mutation
Genetic drift
Migration

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Cards in this collection (26)

Define allele frequency.
Allele frequency is how common an allele is within a population's gene pool.
Besides natural selection, what three random processes can change allele frequencies in a population?
- Mutation
- Genetic drift
- Migration
Mutation is a random process that adds new genetic to a population when it generates new alleles.
Mutation is a random process that adds new genetic variation to a population when it generates new alleles.
True or False?
A mutation occurring in a somatic (body) cell will be passed on to the next generation and can drive natural selection.
False.
Only mutations in gametes can be inherited; a somatic mutation is not passed on to offspring, so it has no impact on natural selection.
How does natural selection act on the new alleles produced by mutation?
An advantageous allele is more likely to be passed on, as it increases the chance of survival and reproduction, while a disadvantageous allele is less likely to be passed on.
Define genetic drift.
Genetic drift is a non-selective process that occurs when chance events influence the passing on of alleles to the next generation, leading to changes in allele frequencies.
Why are small populations more susceptible to genetic drift than large ones?
Random events cause proportionally larger changes in allele frequencies when there are fewer individuals, so chance can shift frequencies quickly in a small population.
Define bottleneck effect.
Bottleneck effect is a type of genetic drift in which a large population undergoes a dramatic reduction in size, for at least one generation, leading to a loss of genetic diversity.
Define founder effect.
Founder effect is a type of genetic drift in which a small group of individuals separates from a larger population to establish a new one, resulting in reduced genetic diversity.
True or False?
Genetic drift can cause a small population to diverge genetically from other populations of the same species, even without selective pressures.
True.
Because chance has a large effect in small populations, allele frequencies can shift enough for the population to diverge without any natural selection.
Define gene flow.
Gene flow is the addition or removal of alleles from a population, which can result from the migration of individuals between populations.
Gene flow between two populations prevents them from into separate species.
Gene flow between two populations prevents them from diverging into separate species.
How does gene flow counteract the effects of natural selection and genetic drift between two populations?
The mixing of their gene pools prevents any accumulation of genetic differences between the populations, stopping them from diverging.
Define Hardy-Weinberg principle.
The Hardy-Weinberg principle is a model stating that, if certain conditions are met, the allele frequencies of a gene in a population will not change from one generation to the next.
What are the five conditions that must be met for a population to be in Hardy-Weinberg equilibrium?
- A large population size
- No migration into or out of the population
- No new mutations
- Random mating
- No natural selection
True or False?
The conditions for Hardy-Weinberg equilibrium are commonly all met in natural populations.
False.
The conditions are very rarely, if ever, all met in nature, but they provide a useful null hypothesis for evaluating whether evolution is occurring.
A population that is in Hardy-Weinberg equilibrium is described as , meaning its allele frequencies are not changing.
A population that is in Hardy-Weinberg equilibrium is described as non-evolving, meaning its allele frequencies are not changing.
What does the Hardy-Weinberg equation allow you to calculate and predict?
It allows the calculation of allele and genotype frequencies within a population, and predictions about how these frequencies will change in future generations.
Define allele frequency.
Allele frequency is the proportion of a particular allele among all copies of that gene in a population, expressed as a value between 0 and 1.
In the Hardy-Weinberg equation, what do the letters p and q represent?
- p is the frequency of the dominant allele
- q is the frequency of the recessive allele
Because there are only two alleles for the gene, their frequencies add up to give the equation p + q = .
Because there are only two alleles for the gene, their frequencies add up to give the equation p + q = 1.
What is the full Hardy-Weinberg equation relating the three genotype frequencies?
p² + 2*pq + q^2^ = 1*
- p² = frequency of the homozygous dominant genotype
- 2*pq = frequency of the heterozygous* genotype
- q² = frequency of the homozygous recessive genotype
In the Hardy-Weinberg equation, the term represents the frequency of the heterozygous genotype.
In the Hardy-Weinberg equation, the term 2*pq* represents the frequency of the heterozygous genotype.
When solving a Hardy-Weinberg problem, why should you always start with the recessive phenotype?
The recessive phenotype is the only phenotype whose genotype is known immediately, because it must be homozygous recessive (q²). This lets you find q, then p, and finally all genotype frequencies.
In a population, 16% of individuals show the recessive phenotype. What is the frequency of the recessive allele, q?
q² = 0.16, so:
q = $\sqrt{0.16}$ = 0.4
True or False?
A change in the allele frequencies of a population over successive generations provides evidence that evolution is occurring.
True.
Stable allele frequencies indicate Hardy-Weinberg equilibrium, so changing allele frequencies show the population is evolving.

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