Breeding Bunnies Honors

Breeding Bunnies Purpose: To model natural selection and describe how the gene frequencies in a population change over time. Procedure: POPULATION #1: Equilibrium 1. The black beans represent the allele for fur (F) and the white beans represent the allele for no fur (f). The cup represents the English countryside, where the rabbits randomly mate. 2. Place your hand over the cup and shake it (the rabbits are mating). 3. Without looking at the beans, select two at a time. (Two white beans = ff; two black beans = FF; one black and one white bean = Ff) 4. Place the pairs of beans in the appropriate spot on the counting area worksheet. Two white beans go on the white bunny marked ff. Two black beans go on the gray bunny marked FF and one black bean and one white bean go on the gray bunny marked Ff. 5. When you have selected all individuals, count the number of each genotype: ff, FF, and Ff. Write these totals in the first three columns of the data table. 6. Count the alleles from the FF, Ff, and ff bunnies and record it on your data sheet. 7. Place the alleles of the surviving rabbits (which have grown, survived, and reached reproductive age) back into the cup, and then mate them again to get the next generation. 8. Repeat steps 2-7 to obtain information until you have data for at least 5 generations. 9. Determine the allele frequencies of F and f for each generation and record them in the chart. POPULATION #2: Selection Follow the same procedure as population #1, but this time, imagine conditions have been altered; because furless bunnies are truly at a disadvantage in the cold weather and die before they reach reproductive age, any offspring that are homozygous recessive “ff” will not survive. For this simulation make an “x” over the number of individuals in the “ff” column to show that they have died. Rather than put the ff alleles (beans) back into the cup, place them aside since these bunnies did not survive to reproduce. Repeat mating, taking out the “ff” bunny alleles at each generation until you have 5 generations of data. Data Collection: Population #1: Equilibrium FF Generation 1 Generation 2 Generation 3 Generation 4 Generation 5 5 5 6 8 6 # of Individuals Ff 10 10 8 6 6 ff 5 5 6 6 8 F # of Alleles f 20 20 20 20 20 20 20 20 20 20 F # of Alleles f 20 17 20 10 20 20 15 16 4 4 Total # of Allele Frequencies Alleles Frequency of F: Frequency of f: F/(F+f) f/(F+f) 40 40 40 40 40 .5 .5 .5 .5 .5 .5 .5 .5 .5 .5 Population #2: Selection FF Generation 1 Generation 2 Generation 3 Generation 4 Generation 5 7 3 8 8 8 # of Individuals Ff 7 14 4 4 4 6 3 1 0 0 ff Total # of Allele Frequencies Alleles Frequency of F: Frequency of f: F/(F+f) f/(F+f) 40 32 36 24 24 .5 .48 .5555555 .4 .4 .5 .46875 .444444 .6 .6 Data Analysis: Answer the following questions in COMPLETE SENTENCES. 1. Describe the trends in the frequencies of the three genotypes. How did they change over generations in each of the following population conditions: -Under equilibrium conditions? (Pop. 1) 20 -With natural selection? (Pop. 2) 0 2. Describe the trends in the frequencies of the two phenotypes. How did they change over generations in each of the following population conditions: -Under equilibrium conditions? (Pop. 1) the white bunnies were increasing in population -With natural selection? (Pop. 2) the white bunnies died in 5 generations 3. In Population #2, furlessness was selected against through the process of natural selection. It is often said that natural selection acts on phenotype, not on genotype. Explain why this is in the context of our model for Population #2.The reson it is said is the white bunnies have phentoypes not genotypes in them so selection will slowly get rid of them over time. the furless ones were not fit to survive in the cold 4. In Population #2, do you think the allele for furlessness (f) will remain in the rabbit population forever? Explain why/why not.it will not remain in the population since they all died out and they probably weren’t able to breed a healthy offspring to pass on their traits. it will no because they will keep mating and the the mixed turned into grey ones over time CHALLENGE! 1. Following the same procedure as population #1, but this time, after generation 1, a disease affects the bunny population and kills half of the entire population. Without looking, randomly remove half of the bunnies regardless of the alleles. Analyze the remaining bunnies, how do these numbers differ in comparison to Population #1 and #2? How do you think this will affect the future generations? FF Generation 1 Generation 2 6 4 # of Individuals Ff 8 2 F # of Alleles f 10 10 10 10 ff 6 4 Total # of Allele Frequencies Alleles Frequency of F: Frequency of f: F/(F+f) f/(F+f) 20 20 .5 .5 .5 .5 2. Restart your procedure again. This time, humans have discovered a deserted island with no bunnies. They’ve decided to bring over a random group of bunnies to the island, with no specific interest in their fur color. Without looking, randomly choose only half of the population to take to the new island. Analyze the island bunny population. How do these numbers differ in comparison to Population #1 and #2? How do you think this will affect the future generations? FF Generation 1 Generation 2 3 1 # of Individuals Ff 5 7 2 2 ff F 9 9 # of Alleles f 11 11 Total # of Allele Frequencies Alleles Frequency of F: Frequency of f: F/(F+f) f/(F+f) 20 20 .45 .45 .55 .55