JoVE Lab Manual
Lab Bio
Lab Bio
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Hardy-Weinberg & Genetic Drift
Hardy-Weinberg & Genetic Drift
Learning Objectives
At the end of this lab, students should know...
What is the Hardy-Weinberg principle and why is it useful?
The Hardy-Weinberg principle states that in absence of evolution, the allele frequencies of a population will stay the same over generations. This principle is used as a null model for population genetics and allows scientists understand evolutionary mechanisms.
How is Hardy-Weinberg equilibrium calculated?
Hardy-Weinberg equilibrium is calculated by multiplying the frequencies of each allele (p and q) for individual genotypes to calculate the genotype frequencies at equilibrium. p2 + 2pq + q2 = 1; p + q = 1
What are the five assumptions of the Hardy-Weinberg principle?
Infinite population size, random mating of individuals, no genetic mutations, no natural selection, and no gene flow.
What is genetic drift?
Chance events that randomly remove individuals, resulting in new populations that have different allele frequencies from the original population.
What are bottleneck and founder effects?
If a population's size is reduced due to a major event it is called a bottleneck effect, whereas a founder effect occurs when a new colony is started by a few members of the original population.
List of Materials
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Colored beads (each color, 10 different colors)500
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Laptop with spreadsheet capability5
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Paper bag5
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Extra plastic containers for beads5
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Paper plate5
Lab Prep
- Mathematical Modeling
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Before beginning the mathematical modeling exercise make sure each computer has access to an either on or offline spreadsheet software program.
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- Simulation for Hardy-Weinberg and Genetic Drift
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Prepare one set of beads for each pair of students by counting out 50 of one color and then 50 of a second color, for a total of 100 beads.
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Then, place the beads in a paper bag.
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Students will also need extra beads to adjust the population makeup and these can be provided in a joint container for the whole class or instructors can make up additional sets for each student pair.
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Next, create slips of paper and write on these the different experimental scenarios that will test violations of the Hardy-Weinberg Equilibrium.
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Then, create a second set of paper slips to determine which genetic drift scenario the students will test.
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Finally, set out any additional beads needed for the experimental scenarios listed on the strips.
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NOTE: An additional 50 beads in a third color will be needed for the mutation violation, and an extra set of 100 beads in the first two colors for the gene flow scenario. For simulating the founder effect with 10 alleles and natural disaster with 10 alleles scenarios, randomly select 100 beads from 10 different colors.
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