Study Guide: Evolutionary Processes and Population Genetics

Q1. Name and explain the significance of the four processes that drive evolution (change in allele frequencies).

Background

Topic: Evolutionary Mechanisms

This question tests your understanding of the main processes that cause changes in allele frequencies within populations, which are central to evolutionary biology.

Key Terms:

• Natural Selection

• Genetic Drift

• Gene Flow

• Mutation

Step-by-Step Guidance

1. List each of the four processes that can change allele frequencies in a population.

2. For each process, briefly describe how it operates (e.g., natural selection favors certain alleles, genetic drift is random).

3. Explain the significance of each process in terms of its effect on genetic variation and population fitness.

4. Consider examples or scenarios where each process might be especially important.

Try solving on your own before revealing the answer!

Q2. True or false? Natural selection is the only process responsible for evolution.

Background

Topic: Evolutionary Mechanisms

This question checks your understanding of whether natural selection is the sole driver of evolutionary change, or if other processes also contribute.

Key Terms:

• Natural Selection

• Genetic Drift

• Gene Flow

• Mutation

Step-by-Step Guidance

1. Recall the four main evolutionary processes.

2. Consider whether each process can change allele frequencies independently of natural selection.

3. Think about examples where evolution occurs without natural selection (e.g., genetic drift in small populations).

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Q4. In a population of forest mice, 62 were trapped and labeled, and 14 were gray (recessive homozygotes, a/a). What are the expected frequencies of alleles A and a, assuming Hardy–Weinberg equilibrium?

Background

Topic: Hardy–Weinberg Equilibrium and Allele Frequency Calculation

This question tests your ability to use population data and the Hardy–Weinberg principle to estimate allele frequencies.

Key Terms and Formulas:

• Allele frequency: proportion of a specific allele in the population

• Hardy–Weinberg equilibrium: $p^2 + 2pq + q^2 = 1$

• $p$ = frequency of dominant allele (A), $q$ = frequency of recessive allele (a)

Step-by-Step Guidance

1. Identify the total number of mice ($n = 62$) and the number of gray mice ($a/a$ genotype, $n_{a/a} = 14$).

2. Calculate the frequency of the $a/a$ genotype: $q^2 = \frac{14}{62}$

3. Take the square root to find $q$ (frequency of allele a): $q = \sqrt{q^2}$

4. Calculate $p$ (frequency of allele A): $p = 1 - q$

5. Compare your calculated values to the answer choices provided.

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Q8. In your own words, explain the Hardy-Weinberg Principle.

Background

Topic: Population Genetics

This question asks you to summarize the Hardy-Weinberg Principle, which is foundational for understanding how allele and genotype frequencies behave in populations under certain conditions.

Key Terms:

• Hardy-Weinberg equilibrium

• Allele frequency

• Genotype frequency

Step-by-Step Guidance

1. Recall the conditions required for Hardy-Weinberg equilibrium (no mutation, random mating, no gene flow, infinite population size, no selection).

2. Describe what happens to allele and genotype frequencies under these conditions.

3. Explain why this principle is important for detecting evolutionary change.

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Q11. What are the five assumptions of the Hardy–Weinberg model? Explain the significance of each assumption.

Background

Topic: Population Genetics

This question tests your knowledge of the conditions required for Hardy–Weinberg equilibrium and why each is important.

Key Terms:

• Mutation

• Random mating

• Gene flow

• Population size

• Selection

Step-by-Step Guidance

1. List each of the five assumptions (no mutation, random mating, no gene flow, infinite population size, no selection).

2. For each assumption, explain how violating it would affect allele or genotype frequencies.

3. Discuss the biological significance of each assumption in real populations.

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Q32. Explain genetic drift.

Background

Topic: Evolutionary Mechanisms

This question asks you to describe genetic drift, a process that causes random changes in allele frequencies, especially in small populations.

Key Terms:

• Genetic drift

• Random sampling

• Population size

Step-by-Step Guidance

1. Define genetic drift and explain how it differs from natural selection.

2. Describe how genetic drift operates in small versus large populations.

3. Discuss the consequences of genetic drift for genetic variation and allele fixation/loss.

Try solving on your own before revealing the answer!