Evolutionary Bio Test 2 Week 2
Evolutionary Bio Test 2 Week 2 12050 - BIOL 3350 - 001
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This 6 page Class Notes was uploaded by Adam Rodenberg on Friday February 5, 2016. The Class Notes belongs to 12050 - BIOL 3350 - 001 at Clemson University taught by Dr. Michael Sears in Spring 2016. Since its upload, it has received 176 views. For similar materials see Evolutionary Biology in Biological Sciences at Clemson University.
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Date Created: 02/05/16
Evolutionary Bio Test 2 Week 2 This set of notes includes everything Dr. Sears covered in class plus all of the vocabulary and major notes from the textbook from this week. 2/9/16 Chromosome mutations Chromosomal inversions through radiation, etc. both ends of a chromosome can break, mistakes can be made. Inversions suppress crossing over, resulting in ‘super genes’. Are these^ important in evolution? selection might favor certain chromosomal inversions to help maintain combinations of alleles across nearby loci. Genome duplications duplications of the entire genome are an important mechanism of speciation especially in plants It can be used as a mechanism for adaptation changes in ploidy can alter phenotypes in a way that makes individuals better adapted to new environments Gene duplications in tiger salamander female chooses how much of the males genetic material she passes on. Females incorporate male genes, but increase ploidy levels. Female replaces some of her genetic material with that of the males from clipping his out. Rates and fitness effects of mutations mutation accumulation experiments demonstrate that mutation rate evolves. gene duplications can be more common than mutations Gene duplication is more common than a point mutation The distribution of fitness of new mutations many of the mutations accumulation lines carried beneficial mutations Types of mutations lethal, deleterious, neutral, beneficial Lethal and deleterious mutation outnumber neutral and beneficial mutations Balance btwn mutation and natural selection it’s the action of natural selsection, culling damaging mutations and preserving the advantageous on, that saves the populations from the inexorable decline. (they used nematodes to experiment on; forcing mutations on them, and seeing how natural selectin effects the following populations. In the experiment, natural selection almost immediately returned to the original genome) Population genetics**** marries Mendelian genetics with Darwin’s theories of natural selection from a population geneticists’ perspective, evolution can be defined as change across generations in the frequencies of alleles. From a geneticists’ perspective, evolution can be defined as change across generations in the frequencies of alleles By random chance alone, populations evolve due to slight changes in allele frequencies Calculating allele frequencies HardyWeinberg principle (p + q) = p + 2pq + q = 1 HW conclusion1 the allele frequencies in a population will not change, generation after generation HW conclusion 2 If the allele frequencies in a population are given by p and q, the genotype frequencies will be given by p2, 2pq, and q2. 2/11/16 Reaction norm Cline HW assumptions no selection, no mutation, no migration, no chance events, random mating Mechanisms of evolution mutation, drift, selection, migration(organisms come in from dif populations) How to know when a population is not in HW equilibrium Chisquared test Chi squared test x⌃2= E(observed expected)2/(expected) Degrees of freedom df= k1m Expected for AA = (P^2)N Expected for Aa= 2PQN Expected for aa= (Q^2)N N=total Selection happens when individuals with particular phenotypes survive to sexual maturity(or reproduce) at a higher rate than organisms with other phenotypes. Strong selection vs weak selection strongquick change weak slower change Fruit flies differentiate when grown in different media Can humans evolve in response to HIV/AIDS? certain alleles occurs in humans that Textbook Vocab Ch. 5 Genetic variation diversity in gene frequencies Environmental variation genetic variation resulting from environmental influences Genotypebyenvironment when two different genotypes respond to environmental variation in different ways Genome the corpus of genetic instructions carried by an individual Alleles different versions of a gene Genotype the combination of alleles an individual carries Phenotype the suite of an individual exhibits Inducible defense growth of armor in response to phantom midge kairomone Expression production of proteins Epigenetic marks Features not directly governed by the genetic code Phenotypic plasticitya characteristic of organisms who develop different phenotypes in different environments Mutations changes in the genome Premutations alterations to DNA due to chemical degradation and replication errors must evade correction to become persistent mutations Point mutation the substitution of one base for another (the smallest possible mutation) Transition substitution of a purine for a purine or a pyramidine for a pyramidine Transversion substitution of a purine for a pyramidine or vice versa Synonymous(silent) mutation a mutation that leaves the protein unaltered Nonsynonymous(replacement) substitution a mutation that changes the amino acid specified by a codon Nonsense mutation a mutation that introduces a premature stop codon Introns noncoding sequences Exons coding sequences Indels point mutations, insertions, and deletions Gene duplications unequal crossing over, retroposition, or retroduplication Pseudogenes a nonfunctional gene that lacks regulatory sequences thata cause it to be transcribed Paralogous genes that are located in a genome and later diverge in function Orthologous genes derived from a common ancestral sequence and separated by a speciation event Inversions a chromosome rearrangement in which a segment of a chromosome is reversed end to end Linkage the tendency for alleles of different alleles of different genes to assort together at meiosis Polymorphic chromosomes with and without specific inversions exist Cline regular change in the frequency of an allele or an inversion over a geographic area Polyploid organisms with more than two chromosome sets Mutation accumulation the evolutionary effect of adverse events declines following the age at which an organism is initially capable of reproduction Ch. 6 Population genetics integrates evolution by natural selection with Mendelian genetics Population a group of interbreeding animals and their offspring Gene pool all the eggs and sperm produced by all the adults in the population, dumped into a (figurative) barrel Genetic drift the fact that blind luck can cause a population to evolve unpredictably Selection what happens when individuals with particular phenotypes survive to sexual maturity to produce offspring than those with other phenotypes Heterozygote superiority/Overdominance a hypothesis in which heterozygotes have higher fitness than either homozygote Underdominance the selection against the mean of a population distribution, causing disruptive selection and divergent genotypes Frequencydependent selection when selection favors one character until it becomes too common, then switches to favor another character Mutationselection balance when the rate at which copies of deleterious allele are being eliminated by selection is equal to the rate at which new copies are being created by mutation, the frequency of the allele is at equilibrium
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