Evolutionary Bio Quiz 2 Study online at https://quizlet.com/_dphgqi Describe how artificial selection reinforces the theory of evolution by natural selection 1. The individuals within a population differ from each other 2. The differences are, at least in part, passed from parents to offspring -Variation is heritable /variable 3. Some individuals are more successful at surviving and reproducing than others -Has to be variation in fitness 4. The successful individuals are not merely lucky; instead they have succeeded because of the variant traits they have inherited and will pass to their offspring - Link between the individuals not having the same # of offspring and the variant traits Explain and recognize each of Darwin's four postulates The force of selection is acted ON the individual but the level of Explain the role of individuals, populations, and time (generations) change is regarded FROM the population. in the process of natural selection For natural selection time (generations) have to pass It is the "currency of natural selection" Describe fitness in the context of natural selection, and how fitness Fitness is the contribution of genes to the next generation (meanis relative ing the ability to survive and reproduce) Fitness is relative because of the reproductive rates Finches are locked into one place and evolution has happened recently making it easy to study evolution. Postulate 1: variation? - Yes the beak depths varied within the population Postulate 2: Heritable? - Yes we can tell if the variation is heritable by determining if the offspring are more likely to resemble their parents than other Use the example of Galápagos finches to explain the process of non-relatives using a midparent-offspring regression. natural selection, with specific references to Darwin's postulates Postulate 3: differences in fitness? - Yes not all finches born will survive and reproduce (Always more offspring produced than survive and reproduce) Postulate 4: variation in fitness NON-RANDOM? - Yes survival and reproduction are non-random. Only large beaked birds could eat the seeds when a drought came in and killed the smaller seeded plants so therefore more large beaked birds survived. Adaptive radiation: Evolutionary process in which ancestral species give rise to a diverse array of descendent species with great ecological, morphological or behavioral diversity Example: Darwin's finches are a example of adaptive radiation, because they went on to evolve a diverse array of species. Define, and provide an example of an adaptive radiation Modern synthesis integrated genetics with Darwin's four postulates and led to a reformulation of the theory of evolution. -Two propositions: The first being that gradual evolution results from small genetic changes that rise and fall in frequency under natural selection. - The second was that the orgion of species and higher taza, or macroevolution can be explained in terms of natural selection acting on individuals or microevolution. Explain the role of the Modern Synthesis in our current understanding of evolution We now think of evolution in terms of changes in the frequencies of the alleles responsible for traits like beak depth and flower color. Heritability fraction of phenotypic variation attributable to genetic differences If all postulates are satisfied does that mean evolution HAS happened? NO -It just means that evolution CAN happen modern synthesis an evolutionary framework that incorporates natural selection, Mendelian inheritance and population genetics 1/5 Evolutionary Bio Quiz 2 Study online at https://quizlet.com/_dphgqi Explain the advantages of using molecular data to reconstruct phylogenies It is relatively easy to build a very large data matrix Which is important because the more sample you have the better for variation purpose - Allows you to avoid homoplasy by using a large data set Describe the importance of DNA sequence alignment for phylogenetics DNA sequence alignment allows us to compare and define homologous characters and creates our character matrix. Transitions are nucleotide substitutions where a purine is replaced with a purine (or pyrimidine with a pyrimidine) Transversions are substitutions where a purine is replaced with a Explain why transitions and transversions may be treated differpyrimidine or visa versa. ently in a model of DNA sequence evolution These may be weighed differently depending on the type of replacement in parsimony you treat each site in sequence as an independent character and look for synapomorphies that identify monophyletic groups. in maximum likelihood: - Uses a model of DNA sequence evolution - If we have a proposed evolutionary tree, with branch lengths measured in expected number of substitutions per site, and a Understand how Parsimony and Maximum Likelihood can both be model of sequence evolution—a set of numbers describing the used to reconstruct a phylogeny from DNA sequence data rates at which the various possible substitutions occur—we can calculate the probability of evolving the particular set of sequences we have found in our data. The probability of the data given a tree, its branch lengths, and a model of evolution is called the likelihood They can both be commonly used L (tree) = P (data|tree, branch length, model) Explain the terms of the Maximum Likelihood function (you do not The probability of the data given the tree and the model is equal need to memorize the function itself, or do any calculations) to the product of the data given the tree and the model for each site in the character matrix Q matrix: From JC (all equal, one rate) to GTR (all varied, 6 rates) Identify the parts of a model of sequence evolution: Q matrix, base DNA base frequencies: assumed to be equal or estimated frequencies, rate variation Rate variation: equal for all sites or allowed to vary between sites (sites are columns aligned in the character matrix) Explain the process of bootstrapping and how it is a measure of confidence in a tree The generation of artificial data sets by random sampling with replaceemnet from the actual data set. Analyzing the data set gives us an idea of how much the results might change if the study were replicated that many times The rate or amount of evolution (change that occurred In maximum likelihood as the optimality criterion branch length represent - Measure length due to the rate of substitution homologous alignment they all came from the same spot in the ancestor describes the rate of change for each kind of DNA substitution Q-Matrix (Part of model of evolution) T/F all substitutions are equal False - Transitions and transversions are not equal and transitions are observed much more often i real sequence data Reminder A to G = transitions (all gold is pure) 2/5 Evolutionary Bio Quiz 2 Study online at https://quizlet.com/_dphgqi - Purines C to T are transversions Bootstrapping provides a measure of statistical support for each branching point (node) in a tree Bootstrapping This is a example of: Vp=Vg+Ve - Vp: phenotypic variation (expressed variation, things we can see and measure) 1. Genetic (Vg) - Allelic variation Describe, and provide examples of the three types of variation - Ex: pigmnet differences in mice form one allelic difference that underlay phenotypic variation: Genetic, Environmental, and 2. Environmental (Ve) Genotype-by-environment - organisms phenotype can change due to the environment - Ex: Inducible defenses 3. genotype-by-environment (Vgxe) - differences among individuals encoded in the genome in the way the environment influences phenotype - Ex: Heat shocked black caterpillars to see how green they turn Allele: one varsion of a gene Genotype: combination of alleles carried by an individual Understand the relationship between alleles, genotype, and phePhenotype: suit of traits expressed by an individuals notype - Phenotype doesnt always have to be visible (blood type, sensitivity to smell, etc...) in environmental variation phenotypes can Change due to the enviornment Explain the difference between environmental variation and genoIn genotype-by-environment phenotypes are expressed from type-by-environment variation in the context of phenotypic variavarying levels of response to environmental stimulate among the tion genotypes - Phenotype dosen't change just expressed at different levels due to the genotype Mutation can lead to substitution 1. Synonymous substitution - Mutation that Does NOT alter protein - does not change the amino acid and therefore does not change the phenotype Describe the different types of mutations and their relationship to allelic variation and how they may be acted upon by selection 2. Nonsynonymous substitution - Mutation that DOES alter protein - Change the amino acid so possibly changes the phenotype too 3. Nonsense mutation - mutation that introduces premature STOP codon New genes arise - unequal crossing over - retrotransposition Provide examples of how entirely new genes may arise 3/5 Evolutionary Bio Quiz 2 Study online at https://quizlet.com/_dphgqi (Processed mRNA reverse transcribed and integrated into the chromosome) Hardy-Weinberg throrem characterizes the distributions of genotype frequencies in populations that are not evolving and is thus the fundamental null model for population genetics Population Group of interbreeding individuals and their offspring List and understand the principles and assumptions of Hardy-Weinberg equilibrium. - In a large population mating randomly, allele frequencies do not change from 1 generation to the next - In an idealized population (large, random mating), the population does not evolve - Genotypic frequencies can be calculated from allele frequencies T/F The distribution of allele and genotype frequencies will not change from generation to generation if a population is in Hardy-Weinberg equilibrium True Allele frequencies under HWE p+q=1 Genotypic frequencies under HWE p^2+2pq+q^2=1 p:the frequency of A q: the frequency of a Calculate genotype and allele frequencies for populations in Hardy-Weinberg equilibrium. using allele frequencies to predict genotype frequencies example 1. no selection 2. no mutation 3. no migration 4. no drift (chance events) 5. Individuals mate randomly What are the assumptions of Hardy-Weinberg equilibrium? (^all of the above are evolutionary forces) No selection - if no selection is happening then individuals of all genotypes will survive at equal rates and have equal fitness - When we implicit selection (or it occurs) we calculate the frequencies of alells that will make up the ext gen. of gametes - Evolution occurs The final allele frequencies differ from the initial - Results in a change in allele frequencies For each assumption of Hardy-Weinberg equilibrium (no selection, no mutation), explain how violating that assumption results No mutation in change in genotype frequency, allele frequency, or both. - if there is no mutation then one allele cannot convert to the other during meiosis - When mutation occurs during meiosis tehre is a certain rate of mutation that converts A to a (example) - If the mutation rate is 1 in 10,000 then we calculate new allele frequencies - Evolution happens but not much Selection acts on _______ genotypes 4/5 Evolutionary Bio Quiz 2 Study online at https://quizlet.com/_dphgqi Predict the direction and rate of change in allele frequencies when given information about selection and mutation rates. Explain why mutation alone is not a strong evolutionary force. Mutation alone is not a strong evolutionary force because it is important for creating variation but without variation it isn't fast enough to cause a impact Explain how mutation and selection together can produce relatively rapid evolutionary change. Beneficial mutations that arise and are favored by selection deletrious bad Use an example to explain the concept of mutation-selection balance. if deleterious alleles are eliminated at the same rate as new deleterious alleles arise there is mutation selection balance Evolution is a unified theory that explains the origin of biodiversity, from molecules to species Explain why transitions and transversions may be treated differently in a model of DNA sequence evolution 5/5
