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UNC-Chapel Hill BIOL 201 - Exam 1 Study Guide

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BIOL 201 1st EditionExam # 1 Study Guide Lectures: 1 – 9- Bring calculator- Bring scantron- Exam is Tuesday Feb. 10th. Lecture 1I. Myths of Evolutiona. scientific theory: statement of what are known to be the general laws and principles of something known or observed; based on evidence; NOT just a guess/belief; is set of factsb. Evolution: descent with modification and often diversification; observable and testablei. Also can be defined as a change in the properties of groups of organisms over the course of generationsii. NOT a theory about the origin of life. It occurs at the level of populations. Populations evolve NOT individuals.iii. And individual canNOT be born as one species and evolve into another.iv. Mutations are NOT always detrimental.v. Evolution doesn’t always proceed from more simple to more complex.vi. Not like a ladder; more like a tree. Climbing up is not like climbing a ladder of progress with organisms getting better as you go up.c. Natural selection does NOT give organisms what they need. It doesn’t give you what you need.II. Phenotype vs. Genotypea. The environment can affect the phenotype more than the genotypei. Ex: dying hair or not eating enough causing growth to be stunted even if you have the gene for being tallb. environment + genes = phenotypeIII. Discrete Traitsa. Without this idea of discrete traits we’d have blending inheritance so a tall dad and a short mom the kids would be medium heightb. Would lead to the entire population starting to look the same and would be little to no phenotypic variation and no natural selectionc. Mendelian inheritance keeps all of the phenotypic variationIV. Genotype and Allele Frequencya. Genotype frequency: # of individuals with particular genotype divided by total number of individuals observedb. Allele frequency (of A): # of individuals with AA + ½ (# individuals with Aa)Lecture 2I. Hardy-Weinberg Equilibrium: If a population is free from evolution (microevolutionary forceslike mutation, migration, and natural selection) then allele frequencies won’t change. The proportions  f(AA) = p2 f(Aa) = 2pq and f(aa) = q2 where p = f(A) and q = f(a) will occur for genotype frequencies.i. In normal population, HW proportions are always present after random mating until something else happens  evolutionii. Equilibrium is reached if you magically stop evolutioniii. Can use departure from HW equilibrium to prove that evolutionary forces are actingb. Assumptionsi. Infinite population size (no genetic drift), no selection, no mutation, no migration, and random mating which means no sexual selection. II. MHC Loci Example: Do genotype frequencies at the MHC loci of humans conform to the HW model?i. MHC is part of immune system and locus is used in pathogen regulationii. Shows way more heterozygotes at both loci studied than expected which shows that some kind of evolutionary force is actingiii. Can’t tell from this what specific force that isb. Possible Explanationsi. Non-random mating  humans may be able to sense MHC and therefore chose mates based on which they haveii. Natural selectioniii. Can’t tell which explanation it is though. The first step is to determine if HW proportions are present in detecting evolution.III. Heterozygosity: average of how many heterozygotes there are arounda. Heterozygotes have one type while there are two homozygote types (AA and aa).b. Low heterozygosity indicates a very small population that is usually under genetic driftIV. Continuous Traits – like height, weight, or length of a tail, shows normal distribution bell curve, and more people leads to a more normal distributiona. Meanb. Variance: determines how fast a population can respond to evolutionary change and is a departure from the meanc. Coefficient of Variation: makes variance unitless so that you can compare objects/things of different sizesd. Correlation: measures how 2 related variables are to one anotherV. Variation  evolution requires genetic variation but not all variation is important for evolution.a. Phenotypic = genetic variation + environmental variationi. VP = VG + VE b. Genotypic = (also called genetic) additive genetic variation + dominance or non-additive genetic variation; is important for evolutioni. VG = VA + VDii. Additive variation is important part of equation because it describes the variance that is actually passed from parent to offspringiii. Natural selection can only act on variation that is phenotypically apparent and if there’s no evolution then additive variation doesn’t change.iv. Genetic variation can be lost due to selection when one particular side of distribution is favored/unflavored; it’s generated by mutation and recombination.VI. Heritability a. Broad sense vs. Narrow sensei. Broad sense = VG/VPii. Narrow sense  h2 = VA/Vp *h is not squared, just written that wayiii. Evolution is really only affected by narrow sense heritability, it determine the relationship btwn the parent and the offspring generationiv. If there’s no relationship then there’s no heritability. If can perfectly predict thenheritability is 1.v. Narrow-sense heritability is the slope of a graph of midparent phenotype vs. midoffspring phenotypevi. Midparent and midoffspring just means average of the phenotype between bothparents or all offspringVII. Brief history of evolutionary thoughta. Greeks  pre-evolutionary thoughti. Plato: didn’t think things changed at all or were related at allii. Aristotle: linear scale of life like a factory; everything is put together to look the same but there are slight differences due to errorsb. Christian Theologyi. John Ray: idea that living things could be classified logically, evolutionary theorist, believed it was all God’s thought, early naturalist and systematistii. Carl Linnaeus: came up with system of classification with genus, species, etc., creationists, species made by God and others come from cross-breeding iii. Louis Agassiz: believed that world was NOT static so there were ice ages and things like that , big Darwin critic and staunch creationistc. Pre-Darwinian evolutioni. George-Louis Leclerc de Buffon: alterations of animals over time but not over the lifespan of one animalii. Believed that species classification is human invention and merely a way to organize thingsiii. Thought changes were degradationsiv. Homology: same components with different functions show relationship between organismsv. Jean-Baptist Lamark: Philosophie


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