BIOL 3350 Week 5 Notes
BIOL 3350 Week 5 Notes 12050 - BIOL 3350 - 001
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12050 - BIOL 3350 - 001
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This 0 page Class Notes was uploaded by Kennedy Deaver on Friday February 12, 2016. The Class Notes belongs to 12050 - BIOL 3350 - 001 at Clemson University taught by Dr. Michael Sears in Fall 2016. Since its upload, it has received 35 views. For similar materials see Evolutionary Biology in Biological Sciences at Clemson University.
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Date Created: 02/12/16
BIOL 3350 Chapter 5 continued Chromosome Mutations Chromosome inversions radiation or mutation causes chromosomes to break and mistakes are made in binding the broken ends back to the chromosome Linkage genes on chromosome linked physically close together or by function 0 2 genes closer together are more likely to be inherited together Chromosomes cannot line up because of inversions limits crossing over linkage goes up o Super genes inherited together because they can t line up oAre they important in evolution o Geographical pattern in genome duplications in dros o Can track the genomes of animals as they track latitudes o Exact same patterns of inversions in Americas as in Europe Selection may favor certain inversions Genes inherited as super gene are naturally selected o Cline pattern oGenome duplication o Common in plants Can self fertilize Don t get improper cell division Tetrads cannot reproduce with diploids Have a new founder that could potentially start a new population o Yarrow plant Tetrapoid and hexaploid Create neohexads have never experienced nature Hexaploids had lowest survivorship tetraploids had lowest and neo were in between o Animals can do this too Tiger salamander Females have all the power 0 Pick and choose how much male DNA to incorporate into their own Selections works better if there s more genetic variation Rates and Fitness Effects of Mutations 0 Bring into totally benign environment doesn t select for certain individuals o High mutations in virus could help them develop resistance to drugs 0 Mutation is a trait that can evolve Chapt Everyone is a Mutant o Inherit mutations from parents o In US 92 of mutations come from male sperm o In Nigeria more mutations came from female egg oVariation between genders geographically between individuals Sitedirected mutagenesis Pick a base pair and mutate it in bacteria genome 20 were lethal However most didn t do anything didn t in uence tness in any way Some had reduced tness and few increased tness 4 types of mutations Accumulation put yeast in benign environment where it accumulated mutations Did the same thing with plants o Most of the mutation didn t in uence the number of fruits produced o Huge portion that increased tness 4 kinds of mutations lethal deleterious neutral and bene cial o Majority are neutral Balance between mutation and natural selection o C elegans Have control lines natural selection still acting on these Did mutation accumulation experiment surviving to maturity declined by 10 Didn t have natural selection getting rid of bad mutations creates subpar population Put them back together and survival rates back up to the level of the control group o Natural selection acts on random mutations and reduces damaging mutations and preserves advantageous ones OIO er 6 Population Genetics Integrates evolution by Darwin with Mendelian genetics Evolution change in frequency of allele Life cycle of an idealized population o No selection no genetic drift no gene ow no sexual selection random mating Adults choose their mates at random o Gene pool all have certain allele Calculating allele frequencies Gene frequencies have changed due to random chance 0 Population has evolved just due to random chance Punnett square re ects proportion of alleles in gene pool oWhen chance plays no role 0 Can calculate the gene frequency of A using proportions o AA5Aa 0 Have to add to 1 Yule vs Punnett o Punnett proportions stay the same no matter what you start with if no selection p q 1 p q2 p2 2pq q2 1 HardyWeinberg equilibrium oThe allele frequencies in a population will not change o If the allele frequencies in a population are given by p and q the genotype frequencies will be give by p2 2pq and q2 oThere is no selection no mutation no migration no chance events random mating oln nature these things are not true o If population not in equilibrium one of these factors is in uencing genotype Mutation during gamete production 0 Individuals migrate in m M w 1787 3039 1303 Genotype frequencies 17876129 30396129 13036129 029156 049584 021216 Gene frequencies M p 1787 5 x 3039l6129 054 N q 1303 05 x 3039l6129 046 Expected genotype frequencies assuming the population is in Hardy Weinberg equilibrium MM 029104 x 6129 1783 MN 049688 x 6129 3045 NN 021208 x 6129 1299 How well do observed agree with expected Assumptions of HardyWeinberg Equilibrium 1 There is no selection 2 There is no mutation 3 There is no migration 4 There are no chance events in nitely large population size 5 Individuals choose their mates at random Mechanisms of Evolution 0 Mutation Any nucleic acid can change in one direction or another 0 Drift Small population size 0 Selection Pulling out certain alleles Can have selection without evolution 0 Migration Bring in new genetic material 0 How do we know when a population is not in HW equilibrium 0 Chisquare Chisquared test 0 Use test statistic 0 Degrees of freedom How many choices do you have before you have no more meaningful choices Genotype Frequency Expected obs exp2 AA 35 366 Aa 48 447 aa 12 136 P62 q38 AA p2N 0384 95 366 Aa 2qu 2 047 95 447 aa q2N 014 95 133 366 352366 447482447 133 122133 Add them all up 044 Compare to 3841 which is less 0 Selection 0 When individuals with particular phenotypes survive to sexual maturity at higher rates than those with other phenotypes or when individuals with particular phenotypes produce more offspring during reproduction than those with other phenotypes o Takes away particular individuals with certain phenotypes Calculating gene frequencies under selection 0 W tness 0 Genotype with highest number of survivors 1 0 Add up tness of each genotype to nd avg tness 0 Use formulas to predict how gene frequencies may change over time in a population 0 Strong selection vs weak selection Allelic frequencies change by selection 0 Fruit ies attracted to alcohol 0 Fast allele metabolize alcohol more quickly than slow allele 0 By raising ies on different media change allele frequencies Selection can change genotype frequencies so that they cannot be calculated by multiplying the allele frequencies 0 Overdominance heterozygote has advantage over homozygotes o No change in allelic freq no evolution Can human populations evolve in response to HIV 0 Initial frequency is too low for two delta 32 to come together and take off
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