Biol 3350 1st Edition Lecture 11Outline of Last Lecture I. Evolution: the change in allele frequencies over timeII. Hardy-Weinberg Equilibriuma. Consequencesb. Assumptionsc. Implications of HWEd. Using HWE as a test for evolutionOutline of Current Lecture I. What is natural selection?II. Deviations from Hardy-Weinberg EquilibriumIII. Measuring natural selectionIV. Differential survivalV. Differentiation fecundityVI. Absolute fitnessVII. Relative fitnessVIII. Change in allele frequency due to selectionCurrent LectureI. What is natural selection?a. Non-random differential proliferation of phenotypes within a generationb. Differential proliferation is a relative term à more favorable ones become more common in the next generationc. Natural selection interacts with the organisms interface to the environment à aka the phenotyped. Natural selection works within generations, but changes are seen between generations which is evolutione. Natural selection can also favor the mean phenotype which would mean changesaren’t occurring from generation to generation so evolution doesn’t always occurwith natural selectionThese 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.II. Deviations from Hardy-Weinberg Equilibriumi. Particular properties of populations or phenotypes can be used to infer evolutionary forceii. Mechanisms of change: mutation, migration, genetic drift and inbreeding,natural selection and sexual selectionb. If population is not is HWE, conclude that some kind of force of evolution is acting on itc. The differences in survival change the strength in selection and the rate at which allele frequencies changed. Very little differences – rate of change is very slow and selection is weake. Very large differences – fast rate and selection is acting to rapidly change the nextgenerationsIII. Measuring natural selectiona. Fitness is the currency of natural selectionb. Absolute fitness = W = probability of survival x reproductive outputi. Contribution of phenotype to the next generationIV. Differential survivala. V = viability = probability of individual survivalb. Zygote à adultV. Differentiation fecunditya. M = fertility = number of gametes released per indivudalVI. Absolute fitnessa. W = v * m = viability * fertilityb. Natural selection – measure of relative fitness rather than absolute fitnessVII. Relative fitnessa. w = absolute fitness of phenotype / absolute fitness of “most fit” phenotypeb. Relative fitness – compares everyone in the population to the one who does the bestc. selection coefficient = s = 1 – wi. a measure of the strength of selection against a phenotypeii. Selection coefficient measure how poorly a phenotype does against the best phenotypeiii. The higher number the selection coefficient is, the worst it is doingVIII. Change in allele frequency due to selectiona. ∆p = change in frequency of A1 allele in response to natural selectionb. ∆q = change in frequency of A2 in response to natural selectionc. If ∆p = 0 then locus is in HWE and no evolution is occurring d. If ∆p > 0 then the relative frequency of A1 is increasinge. If ∆p < 0 then the relative frequency of A1 is
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