APLabFishyFrequencies
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School
El Segundo High**We aren't endorsed by this school
Course
MATH AP
Subject
Biology
Date
Jan 9, 2025
Pages
3
Uploaded by CommodoreSardine4800
AP Lab 8 Fishy Frequencies 2011 Modified by Lee Ferguson, Allen High School, from a lab by Judith Jones and Judith Stanhope Page 1 of 3 AP Lab 8: Fishy Frequencies (Hardy-Weinberg Equilibrium) OBJECTIVES: After completing this lab activity, you will be able to 1.Use data from mathematical models based on the Hardy-Weinberg equilibrium to analyze genetic drift and effects of selection in the evolution of specific populations. 2.Justify data from mathematical models based on the Hardy-Weinberg equilibrium to analyze genetic drift and effects of selection in the evolution of specific populations. 3.Predict what the effects of genetic drift, migration and artificial selection on the genetic makeup of a population will be.Introduction: Understanding natural selection can be confusing and difficult. People often think that animals consciously adapt to their environments—that the peppered moth can change its color, the giraffe can permanently stretch its neck, the polar bear can turn itself white - all so that they can better survive in their environments. It is also believed by many that unfavorable genes tend to disappear from a population entirely. By performing a simulation in which you prey on goldfish crackers of two different phenotypes, you will learn that the previously mentioned misconceptions are incorrect. You will also use a mathematical model to determine whether or not evolution is occurring in your population of goldfish crackers. Background: Facts about the 'Fish' 1.These little fish are the natural prey of the terrible fish-eating sharks - YOU! 2.Fish come with two phenotypes: gold and brown: a.Gold: this is a recessive trait (f); these fish taste yummy and are easy to catch. b.Brown: this is a dominant trait (F); these fish taste salty, are sneaky and hard to catch. 3.You, the terrible fish-eating sharks, much prefer to eat the yummy gold fish; you eat ONLY gold fish unless none are available in which case you resort to eating brown fish in order to stay alive. 4.New fish are born every 'year'; the birth rate equals the death rate. You simulate births by reaching into the container of 'spare fish' and selecting randomly. 5.Since the gold trait is recessive, the gold fish are homozygous recessive (ff). Because the brown trait is dominant, the brown fish are either homozygous or heterozygous dominant (FF or Ff). Hardy-Weinberg: G. H. Hardy, an English mathematician, and W.R. Weinberg, a German physician, both independently worked out the effects of random mating in successive generations on the frequencies of alleles in a population. This is important for biologists because it is the basis of hypothetical stability from which real change can be measured. For fish crackers, you assume that in the total population, you have the following genotypes, FF, Ff, and ff. You also assume that mating is random so that ff could mate with ff, Ff, or FF; or Ff could mate with ff, Ff, or FF, etc. In addition, you assume that for the gold and brown traits there are only two alleles in the population - F and f. If you counted all the alleles for these traits, the fraction of 'f' alleles plus the fraction of 'F' alleles would add up to 1. The Hardy-Weinberg equation states that: p2+ 2pq + q2 = 1. This means that the fraction of pp (or FF) individuals plus the fraction of pq (or Ff) individuals plus the fraction of qq (ff) individuals equals 1. The pq is multiplied by 2 because there are two ways to get that combination. You can get F from the male and f from the female OR f from the male and F from the female.
AP Lab 8 Fishy Frequencies 2011 Modified by Lee Ferguson, Allen High School, from a lab by Judith Jones and Judith Stanhope Page 2 of 3 If you know that you have 16% recessive fish (ff), then your qq or q2value is .16 and q = the square root of .16 or .4; thus the frequency of your f allele is .4 and since the sum of the f and F alleles must be 1, the frequency of your F allele must be .6 Using Hardy Weinberg, you can assume that in your population you have .36 FF (.6 x .6) and .48 Ff (2 x .4 x .6) as well as the original .16 ff that you counted. Procedure: 1.Using a small Dixie cup, get a random population of 10 fish from the 'ocean.' Be sure your hands are clean first!2.Count gold and brown fish and record in your chart; you can calculate frequencies later. 3.Eat 3 gold fish; if you do not have 3 gold fish, fill in the missing number by eating brown fish. 4.Add 3 fish from the 'ocean.' (One fish for each one that died.) Be random. Do NOTuse artificial selection. 5.Record the number of gold and brown fish. 6.Again eat 3 fish, all gold if possible. 7.Add 3 randomly selected fish, one for each death. 8.Count and record. 9.Repeat steps 6, 7, and 8 until you have collected 10 generations’ worth of data. 10.Fill in the class results on your chart. 11.Fill in your data chart and calculation, prepare your graph, and answer the questions. Analysis: Answer these in your BILL. 1.Prepare a graph of your data and the class results. Your graph should plot change in allele frequency over generations. What generalizations would you make about your results? How do they compare to the class results? 2.According to Hardy-Weinberg, what conditions would have to exist for the gene frequencies to stay the same over time? 3.In our lab, we collected 10 generations’ worth of data. Do you think 10 generations an adequate amount to determine whether or not evolution is occurring in the population we are studying? Explain why or why not. 4.Explain which phenotype is NOT favorable to the fish and why? 5.What would happen if it were more advantageous to be heterozygous (Ff)? Would there still be homozygous fish? Explain. 6.What happens to the recessive genes over successive generations and why? 7.Why doesn't the recessive gene disappear from the population? 8.How would each of the following affect allele frequencies over several generations? a.migration b.isolation c.no selection d.non-random mating e.very small population f.mutations noselectionnomutationnomigrationlargepopulationrandommutatingIdothinkitisenoughtimebecausewewerableto848159496amofnaturalselectionstuff.lafffffesfoehomoygousratebecausetheheterozygoteswillhavetherecessivegenewillcontinueappearinginheterozygousindividualtda1fftpfffuhfILp.is9IetnaY.iEaEreaItadaptationallelefreqfgesepfeegchequllit.invaluesavgfrequenciesacrossthemetapopulationcauseslossofgeneticdiversitymorequicklyaddnewallelestogenepoolgenotypesof0989iiiiiiiiiiiiiiiiiiiiiiii
AP Lab 8 Fishy Frequencies 2011 Modified by Lee Ferguson, Allen High School, from a lab by Judith Jones and Judith Stanhope Page 3 of 3 Data Charts: We will also save these as a spreadsheet in Google Drive. Individual Results Generation # of Gold fish # of Brown fish p q P22pq q21 2 3 4 5 6 7 8 9 10 Class Results Generation # of Gold fish # of Brown fish p q P22pq q21 2 3 4 5 6 7 8 9 10 6I0.60.40.360.480.16s0.50.50.140.50.25A80.40.60.160.480.363A0.30.70.90.420.49280.20,80.10,320.6428000.80.40.320.64280.20.80.40.320.64280.10.80.40.320.449882I000.80.40.20.64