Worksheet for the Hardy-Weinberg Lab



Worksheet for the Hardy-Weinberg Lab

Name ______________________ Lab @ M-12, M-2, T-8, T-10, T-2

Definitions:

Natural selection =

Evolution =

Population =

Gene pool =

Allele pool =

State the Hardy-Weinberg theorem:

List the five conditions under which the Hardy-Weinberg theorem holds:

1)

2)

3)

4)

5)

Given a population with two alleles (A and a) at a single gene locus, write the equation for the Hardy-Weinberg theorem:

Given a population with two alleles (A and a) at a single gene locus, what is:

p2 =

2pq =

q2 =

Exercise 11.1

A = __________________ color _______________ allelic frequency

a = __________________ color _______________ allelic frequency

How many diploid individuals are represented in this population?

What would be the color of the beads for the homozygous dominant individual?

What would be the color of the beads for the homozygous recessive individual?

What would be the colors of the beads for the heterozygous individual?

The scientific question is: “What are the genotypic frequencies of the population?” Now, state the Hardy-Weinberg theorem making specific reference to the genotypic frequencies and the colors of the beads.

Predict the genotypic frequencies of the population in future generations in the form of an IF/THEN statement.

Table 11.1

Expected Genotypic and Allelic Frequencies for the

Next Generation Produced by the Bead Model

|Parent Populations |New Populations |

|Allelic Frequency |Genotypic Numbers |Allelic Frequency |

| |and (Frequency) | |

|A |a |AA |Aa |aa |A |a |

| | | | | | | |

| | | | | | | |

| | |( ) |( ) |( ) | | |

Table 11.2

Observed Genotypic and Allelic Frequencies for the

Next Generation Produced by the Bead Model

|Parent Populations |New Populations |

|Allelic Frequency |Genotypic Number |Allelic |

| |and (Frequency) |Frequency |

|A |a |AA |Aa |aa |A |a |

| | | | | | | |

| | |( ) |( ) |( ) | | |

Compare your observed results with your expected results by using the Chi-Square test. (See Appendix B in the lab manual or .)

Table 11.3

Chi-Square of Results from the Bead Model

| |AA |Aa |aa |

|Observed value (o) | | | |

|Expected value (e) | | | |

|Deviation (o-e) = d | | | |

|d2 | | | |

|d2/e | | | |

|Chi-Square | |

|(X2) =Σd2/e | |

What is your calculated probability that your deviations are due to chance alone based on your calculated X2 value and the appropriate degrees of freedom?

What proportion of the population was homozygous dominant?

What proportion of the population was homozygous recessive?

What proportion of the population was heterozygous?

Were your observed results consistent with the expected results based on your statistical analyses? If not, can you suggest an explanation?

Compare your results with those of three other groups of students. How variable are the results for each term?

Do your results match your predictions for a population at Hardy-Weinberg equilibrium?

What do you expect to happen if you continued this simulation for 25 generations?

Is this population evolving?

Explain your response.

Consider each of the specific conditions of the Hardy-Weinberg model. Does this model meet each of those conditions?

1)

2)

3)

4)

5)

Exercise 11.2

Simulation of Evolutionary Change Using the Bead Model

Experiment C

Simulation of Natural Selection

Propose a hypothesis that addresses natural selection in tropical Africa specifically.

Use an IF/THEN statement to make a specific prediction relative to your hypothesis.

Table 11.5

Changes in allelic and genotypic frequencies for the natural selection simulation in Exercise 11.2. Calculate all expected frequencies based on the actual observed numbers in your experiment.

|Simulation of Natural Selection |

|Generation # |Allelic Frequency |Genotypic Frequency |

|0 |p |q |p2 |2pq |q2 |

|1 | | | | | |

|2 | | | | | |

|3 | | | | | |

|4 | | | | | |

|5 | | | | | |

|6 | | | | | |

|7 | | | | | |

|8 | | | | | |

|9 | | | | | |

|10 | | | | | |

|11 | | | | | |

|12 | | | | | |

|13 | | | | | |

|14 | | | | | |

Which of the specific Hardy Weinberg conditions were met in your experiment?

Which of the specific Hardy-Weinberg conditions were NOT met in your experiment?

Briefly describe your simulation.

What were your predicted results?

How many generations did you simulate?

Sketch a graph of the change in p and q as a function of generation #. Your graph will have two lines, one for each frequency.

Describe the changes in allelic frequencies p and q over time. Did your results match your predictions? Explain.

Describe the changes in the genotypic frequencies.

Compare your final allelic and genotypic frequencies with those of the starting population.

Formulate a general summary statement or conclusion based on your experiment.

Would you expect your results to be the same if you had chosen different stating allelic frequencies? Explain.

Browser Based Simulation of Natural Selection

See:

Carefully read the starting scenario and then proceed by selecting the Natural Selection Mode. Choose a starting frequency of the B allele of 0.5. Choose 10% predation against the black flies and 20% predation against the tan flies. Run the simulation.

How many generations does it take to completely remove the tan flies?

Repeat the simulation with a starting frequency of the B allele at 0.25, predation against black at 10% and predation against tan at 20%.

How many generations does it take to completely remove the tan flies now?

Repeat the simulation with a starting frequency of the B allele at 0.25, predation against black at 10% and predation against tan at 10%. (Note that now there is no differential predation.) Run the simulation.

How many generations does it take to completely remove the tan flies? Explain your answer in terms of the Hardy-Weinberg conditions.

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