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Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Breeding Bunnies (Allele Frequency & Evolution) Lab Problem o To model how natural selection affects the allele frequency of a population over several generations. Background Information o Evolution (on a genetic level) can be described as the change in the allele frequencies of a population's gene pool over time. "Selective forces" (ex. breeders, predators, etc.) can select for or against specific phenotypes (traits) and cause a change in the frequencies of the alleles that produce those phenotypes (traits). Changes in allele frequency (and, therefore, evolution), will in turn, affect how often you see a particular phenotype (trait) in a population. o Ex. Breeders of rabbits have long been familiar with a variety of genetic traits that affect the survivability of rabbits in the wild, as well as in breeding populations. One such trait is the trait for furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in the wild because the cold English winters are too harsh for the rabbits and act as a "selective force" against being furless. These rabbits are not well adapted to their environment and, therefore, die before reproducing (and passing on their genes). Vocabulary o allele _________________________________________________________________________________ ______________________________________________________________________________________ o gene pool ______________________________________________________________________________ ______________________________________________________________________________________ o allele frequency _________________________________________________________________________ ______________________________________________________________________________________ o evolution ______________________________________________________________________________ ______________________________________________________________________________________ Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Pre-Lab Questions 1. Let: F (red/brown bean) = furry f (white bean) = NO fur (furless) a. Write the genotype(s) that best fit(s) the description: i. heterozygous __________________________ ii. homozygous dominant __________________________ iii. homozygous recessive __________________________ iv. have fur __________________________ v. furless (NO fur) __________________________ 2. Which phenotype is best adapted for the cold climate of Connecticut? _____________________________ 3. What will happen to the frequency of the genes of bunnies that are not well adapted to survive in the cold? _________________________________________________________________________________ 4. What does each individual bean represent? __________________________________________________ 5. Why do you need to remove two beans for each individual bunny? _______________________________ ______________________________________________________________________________________ 6. What is the shaking of the bag of beans meant to simulate? _____________________________________ 7. What is the best type of graph (bar, circle, line) to show the change in allele frequency over time? ______________________________________________________________________________________ Hypothesis o If rabbits with fur and NO fur (furless) breed randomly over time in Connecticut, then the allele frequency for (fur → F / NO fur → f) will (increase / decrease), because ____________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________. Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Experimental Design o Materials (per group) 50 red/brown beans (to represent the F allele for fur) 50 white beans (to represent the f allele for No fur/furless) 1 paper bag (to represent the countryside where the bunnies randomly mate) 4 cups (labeled FF-furry, Ff-furry, ff-No fur/furless, & “dead bunnies”) (to sort bunnies) Graph paper (for each person) o Procedure 1. Place 50 red/brown and 50 white beans (alleles) in the paper bag. (This may have been done for you). 2. Shake the paper bag (to represent the random mating of the rabbits). 3. WITHOUT looking, select TWO (2) beans from the bag (to represent one offspring). a. The color of the beans will tell you whether you have a homozygous dominant (furry), a heterozygous (furry), or homozygous recessive (furless/NO fur) bunny. 4. Place the "bunny" in the cup (labeled FF-furry, Ff-furry, & ff-furless/NO fur) representing its genotype. 5. Continue until there are no more beans in the bag. 6. For each cup (FF, Ff, & ff), count how many PAIRS of beans you have & write the number of pairs in the correct column (FF, Ff, & ff) in the row next to "generation 1". 7. IMPORTANT!!! The ff bunnies are born furless. The cold weather kills them before they reach reproductive age, so they can't pass on their genes (alleles). a. Place the beans from the ff container in the “dead bunny” cup before beginning the next round. Do NOT put them back in the bag or mix them with the beans in the Ff or FF cups!!! 8. To figure out the “Surviving # of ‘F’ alleles”: count the remaining red/brown (F) beans (from the FF and Ff cups) and record the number in the chart in the column labeled "Surviving # of ‘’F’ Alleles" (column 4). 9. To figure out the “Surviving # of ‘f’ alleles”: count the remaining white (f) beans (from the Ff cup) and record the number in the chart in the column labeled "Surviving # of ‘f’ Alleles" (column 5) a. REMEMBER; don't count the alleles of the ff bunnies that you put aside since they are “dead”. Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ 10. Add the "Surviving # of ‘’F’ Alleles" (column 4) & "Surviving # of ‘f’ alleles" (column 5) for the first generation. Record this number in (column 6) labeled "Total Number of Surviving Alleles". 11. Place the alleles of the rabbits (FF furry & Ff furry) which have survived, grown, & reached reproductive age back in the paper bag. 12. Repeat steps 2 through 11 for each generation (until you have finished all 10 generations or you were told to stop). a. If working as a team, make sure everyone in the group has a chance to select beans and record results. Nobody should do the same job the entire time. 13. Using the formulas below, determine the allele frequency of F and f for each generation and record them in in DECIMAL form on the chart in the columns labeled "Frequency of F alleles" (column 7) and "Frequency of f alleles" (column 8). a. To find "Frequency of F alleles" (column 7): allele frequency of F = "surviving" # of F alleles from column 4 ________________________________________________ total # of alleles from column 6 b. To find "Frequency of f alleles" (column 8): allele frequency of f = "surviving" # of F alleles from column 5 ________________________________________________ total # of alleles from column 6 c. Express results in decimal form (rounded to the nearest hundredth). d. NOTE: The sum of the frequency of column 7 ‘F' + column 8 ‘f’ should = 1 (for each generation). 14. Graph the frequencies in decimal form (rounded to the nearest hundredth) for both alleles on the same graph. a. *****Don't forget to include ALL the features of a good graph. 15. Complete the "Analysis and Conclusions". Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Observations and Data Table 1 (Note: columns 7 & 8 should = 1.0) column column 2 column column 4 1 3 How to count count count Count all figure out PAIRS PAIRS of PAIRS remaining what to do of red red/white of red F for each beans beans white beans column. → beans (from FF & Ff cups) generation #FF bunnies #Ff bunnies 0 n/a n/a 1 2 3 4 5 6 7 8 9 10 column 5 column 6 column 7 column 8 Count all remaining white beans (from Ff cup) column 4 + column 5 column 4 / column 6 column 5 / column 6 #ff "surviving" "surviving" total # of bunnies # F alleles # f alleles "surviving" (red (white alleles beans) beans) (F + f alleles) frequency of F alleles (decimal rounded to hundredth) frequency of f alleles (decimal rounded to hundredth) 0.50 0.50 n/a 50 50 100 Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Analysis and Conclusions 1. Graph the frequencies in decimal form (to the nearest hundredth) for both alleles on the same graph. a. *****Don't forget to include ALL the features of a good graph. 2. How is this lab simulation a model for evolution? 3. What are some limitations (drawbacks) of this type of model? 4. In real life habitats, animals often move in (immigrate) or move out (emigrate). How might immigration and emigration affect the allele frequencies in a population? 5. In generation 1 on your data table, what was the frequency of “F” alleles? ________ ...of “f” alleles? ________ 6. In your last generation on your data table, what was the frequency of “F” alleles? _______ ...of “f” alleles? ______ 7. Did either of the alleles totally disappear? __________ Why/why not? 8. Describe the trends you observed in your data for the allele frequencies. (Ex. Which allele increased in frequency? Which allele decreased in frequency?) (Refer to your data and graph.) 9. Restate your original hypothesis (from the bottom of page 2). 10. Does the data support or refute your hypothesis? Explain your reasoning by referring to your data. 11. How does natural selection (for beneficial traits/against disadvantageous traits) affect allele frequency? 12. Which evolves, individual organisms OR populations/species? Explain your reasoning. 13. If you were to repeat this lab, how could you represent immigration and emigration using beans? Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Make your graph here. Name _____________________________________ Date _________ Mrs. Geithner-Marron (Biology300) Period ________ Extra graph paper (in case you made a mistake).