BCOR 12 1st Edition Lecture 4 Outline of Last Lecture I. Microevolution mechanismsII. Genotypes and allele frequenciesIII. The Hardy-Weinberg PrincipleIV. HW assumptions Outline of Current Lecture I. The Scientific ProcessII. How to Solve an Expected vs. Observed Hardy-Weinberg Problem a. Used to determine if a population is evolvingIII. Mechanisms that affect Allele FrequenciesCurrent LectureThe Scientific ProcessI. Develop hypotheses and generate predictions (expected data)II. Gather data (observed data)III. Compared observed vs. expected dataIV. Analyze results and draw conclusionsProblem: Is this human population evolving at a specific gene locus for an neurodegenerative disorder? 16 people have the genotype DD, 92 people have the genotype Dd, 12 people have the genotype dd. The D allele is the allele for the neurodegenerative disorder.Steps to SolvingI. Determine the total number of each allelesII. Determine allele frequencies (p + q = 1)III. Determine genotype frequencies (Hardy-Weinberg equation: p2+pq+q2=1)IV. Compare expected genotype (what you calculated in step 3) to the observed genotype frequencies.Number of IndividualsGenotype Number of D allelesNumber of d alleles12 DD 24 0These 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.92 Dd 92 9212 dd 0 24Total: 120 124 116*Remember that the number of alleles is doubled for there are two alleles in a genotype. Example: 92 people have genotype Dd so there are 92 D alleles and 92 d alleles in this portion of the populationStep 2: p = (total number of D alleles)/(total number of alleles) p = 124/240 = 0.52q = (total number of d alleles)/(total number of alleles)q = 116/240 = 0.48Step 3: Determine frequency of each genotype using p2+pq+q2=1p2=(0.52)2=0.27 (the frequency of the DD genotype)pq=2(0.52)(0.48)=0.50 (the frequency of the Dd genotype)q2=(0.48)2=0.23 (the frequency of the dd genotype)*multiply these frequencies by the total number of individuals in the population to obtain the number of EXPECTED individuals to have these phenotypes)0.27(120) = 32 0.5(120) = 600.23(120) = 28Step 4: Compare expected vs. observed (observed individuals are the number individuals with the phenotypes given in the problem)Genotype Expected ObservedDD 32 16Dd 60 92dd 28 12Step 5: What does this data mean?Because the observed values are so far from the expected it means that this population is indeed evolving. Mechanisms that Alter Allele Frequencies- Natural Selection, genetic drift (including bottleneck and founder effect), mutations, and gene flow can all alter the allele frequencies in a population- Gene flow – new individuals are coming into the population and reproduce (migration with reproduction)- Genetic drift – random change in allele frequencies in populationo is based on what survives and reproduces- Bottleneck effect – starts with a large population, but it then decreases by a large amount significantly shrinking the alleles/allele frequencies in the populationso Usually caused by natural disasters (i.e. disease, famine,