ZOOL 4133 1nd Edition Lecture 3 Selection, mutation and Hardy-Weinberg 1/22I. Natural selection is a mechanism that drives evolutionII. Evolution requires heritable genetic variationIII. Mutation is the source of new genetic variationIV. Population genetics integrates population variation with geneticsV. gave evolution a mathematical basisWhat processes can cause changes in allele frequencies in a population?I. mutationII. selectionIII. migrationa. gene flow between populationsIV. genetic drifta null model in population geneticsV. model makes the following assumptions:VI.a. no selection b. no mutationc. no migrationd. no genetic drifte. random matingVII. population of micea. calculate allele frequencies in current populationb. predict genotypic frequencies in the next generationcalculating allele frequenciesVIII. count alleles a. i.e. A=120 a=80 total = 200IX. calculate the frequency of each a. always adds up to 1b. A = .6 a=.4X. count genotypes a. AA=.36b. Aa=.48c. aa=.16Predicting genotypic frequenciesXI. allele frequencies in general population a. A = 0.6 a=0.4These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XII. calculate the probability of observing each genotype in offspring generation a.i. Genotypeii. AA .6 x .6 = .36iii. Aa .6x .4 = .48 iv. aA v. aa .4 x.4 = .16b. sum = 1 i. no evolutionXIII. Hardy-Weinberg equilibriumXIV. p^2+2pq=q^2= 1XV. in an idealized population where there is no:XVI.a.i. no selection ii. no mutationiii. no migrationiv. no genetic driftv. random matingXVII. for allele frequencies p and q, the genotype frequencies will be p^2+2pq=q^2= 1 after one generation of random matingXVIII. allele frequencies remain constant from one generation to the nextXIX. the purpose of this is to have a clear numerical prediction for the null hypothesisNo selectionXX. all members ofXXI. Ex:a. B1 = .6 B2=.4b. number of zygotesc. add in selectiond.i. heterozygote - lose 25%ii. homozygote- lose 50%e. # individual/genotypef. X10 gametes/individual combined to gene poolg. final allele frequenciesh.i. smaller #/bigger #XXII. if final #s are not the sameXXIII.a. Hardy-Weinberg does not hold b. allele frequencies do not stay the same from one generation to the nextc. example in notes is extremely strong selectionXXIV. predicting allele frequencies - until frequency = 1XXV.a. chart in notesXXVI. you can vary selectionXXVII.a. it's going to take longer with deeper selectionb.i. over time the frequency of the B1 allele is going to rise above the B2 alleleallele frequency change under selectionXXVIII. example from lab - DrosophilaXXIX.a. start out in a pop of flies - looking at change in frequency of F(allele)b. experimental group - exposed to ethanolc.i. over generation (50 gens) frequency of ADHF allele rises and fixesii.1. presumably does a more efficient job of breaking down alcoholiii. allele frequencies are not constant from generation to generationiv.1. why?2.a. genetic drift (random)b.i. random selection errorXXX. flower beetlesXXXI.a. theres an allele that ____ when it's in the homozygous stateb. double lethal allele = deadc. starting allele frequenciesd.i. .5 of eache. How will the frequency of the lethal allele change across generations?f.i. experimenters are not selecting for anything; letting lethal allele do it's own thingg. one gen of random matingh.i. H-W tells us that: they will all be deadi. each survivor contributes 10 gametes to the gene poolj. decrease in recessive lethal allelek. increase in viable allelel.i. this happens because fewer are dying with each generationii.1. based on the expectations of selectioniii. pop started out will all heterozygotes and they're finem. rare recessive variants are really important in studying human diseasesn.i. what alleles encode these rare variantsXXXII. OverdominaceXXXIII.a. hetero have higher fitness than both classes of homoXXXIV. underdominanceXXXV.a. heterozygote disadvantageb. both classes of homo have higher fitnessXXXVI. frequency-dependent selectionXXXVII. orchidsXXXVIII.a. flower color polymorphismb.i. purple, yellowc. both colors attract beesd. neither one provides a nectar rewarde. Why do both false advertisements persist in nature?f.i. bees looking for nectar alternate between yellow and purple flowersii. whichever color is less common will get more bee visits (pollination)g. H2: color polymorphism maintained by selection by rare phenotypeh. reproductive success of yellow vs purplei.i. H2ii. bees have a slight preference for yellowXXXIX. Allele frequency change with mutationXL. in an idealized population where there is no:XLI.a.i. no selection ii. no mutationiii. no migrationiv. no genetic driftv. random matingXLII. mouse populationXLIII.a. starting with alleles A=.9 and a=.1b.i. no selectionc. what happens with random mating, no selection, but yes to mutationd. H-We.i. .81 for homoii. .18 for heteroiii. .01 for other heterof. add mutation:g.i. 1/10000 in every A alleles mutates to aii. frequencies after mutationiii.1. A =0.9 - (0.9/10000) = 0.899912. a= 0.1+ (0.9/10000) = 0.10009h. it doesn’t do a lot across a few generationsi. across many generations, if same mutation rate, gradually decrease the frequency of big A allelesj.i. slow change isn't the same as no