Hardy-Weinberg Lab

Abstract

The purpose of this experiment was to the Hardy-Weinberg equilibrium in a mating population recreated by us through the use of red and white pieces that represented different alleles. The experiment began with both alleles having the frequency of 0.5, but the population that we recreated went through many different scenarios that simulated real world activities that changed the allelic frequencies of both alleles.

Introduction

In this lab we use the Hardy-Weinberg equation (p2 + 2pq + q2 = 1.0 and p + q = 1), formulated by G.Hardy and W.Weinberg, who believed that evolution is a change in the frequency of alleles in the gene pool of a population. Hardy and Weinberg suggested that some populations may not change if certain conditions occur. These conditions being- large population, random mating, no mutation, no migration, no selection. This results to Hardy-Weinberg equilibrium which you can calculate through the use the Hardy-Weinberg equation.

Supplies

50 white connector

50 red connector

1 medium sized bowl

1 gene frequency data form

Method

1. Label one dish FF for the homozygous dominant genotype. Label a second dish Ff for the heterozygous condition. Label the third dish ff for those rabbits with the homozygous recessive genotype.

2. Place the 50 red and 50 white beans (alleles) in the container and shake up (mate) the rabbits. (Please note that these frequencies have been chosen arbitrarily for this activity.)

3. Without looking at the beans, select two at a time, and record the results on the data form next to "Generation 1." For instance, if you draw one red and one white bean, place a mark in the chart under "Number of Ff individuals." Continue drawing pairs of beans and recording the results in your chart until all beans have been selected and sorted. Place the "rabbits" into the appropriate dish: FF, Ff, or ff. (Please note that the total number of individuals will be half the total number of beans because each rabbit requires two alleles.)

4. The ff bunnies are born furless. The cold weather kills them before they reach reproductive age, so they can't pass on their genes. Place the beans from the ff container aside before beginning the next round.

5. Count the F and f alleles (beans) that were placed in each of the "furred rabbit" dishes in the first round and record the number in the chart in the columns labeled "Number of F Alleles" and "Number of f Alleles." (This time you are really counting each bean, but don't count the alleles of the ff bunnies because they are dead.) Total the number of F alleles and f alleles for the first generation and record this number in the column labeled "Total Number of Alleles."

6. Place the alleles of the surviving rabbits (which have grown, survived and reached reproductive age) back into the container and mate them again to get the next generation.

7. Repeat steps three through six to obtain generations two through ten.

Results

Discussion

A few observations can be made. The number of F alleles does not change. This is because they only appear in the dominant and heterozygous individuals, which were not killed off. The only thing that was killed off was the recessive individuals, which contained only f alleles. The rate at which the frequency of the frequency of f alleles decreased was reverse parabolic, or could be best represented by a root curve. This means as generations pass, the number of ff individuals killed off was decrease. This can be explained by the fact that as there are less f alleles, there is a lower frequency of them, therefore, a lower probability that they would come together to form a recessive ff individual. Although it is likely the ff allele would soon be nonexistent in the population, it would take longer than a linear deterioration.

Conclusion

The purpose of this lab was to examine natural selection in the cold weather by using the red and white connectors. We now know that homozygous dominant with FF pairs are more common than the rest of the pairs. We also learned that natural selection with the dominant alleles (F) is much greater than the recessive alleles (f) when it comes to mating. For instance, roughly 80% of the pairs in half of the trials are with the dominant allele which leads to more pairs being homozygous dominant of FF. There seems to be a fine line between being paired with FF and Ff than being homozygous dominant with ff that didn’t have the necessities to survive for the set season.