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TAMU BIOL 112 - Exam 1 Study Guide
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BIOL 112 1ST EditionExam # 1 Study Guide Lectures: 1 - 11Lecture 1 (September 1)What is evolution?Change in organisms throughout earth’s history; “descent with modification”Myths about evolution:- Always leads to something better- Organisms can influence their own evolution- Evolution is randomViews before Darwin1600’s: Aristotle’s scala naturae (nature ladder)Medieval: Biblical creationism and young earth ideas1700-1800’s: Linnaeus – modeled his classification system like the church was organized.Cuvier – studied fossil change over time and attributed the strata in sedimentary rocks to large floodsHutton – slow, continuous processes produce geological features (ex: Grand Canyon)Lyell (uniformitarianism) – same as Hutton, but believed in an old earth because processesare slow and constant. “Principles of Geology”Erasmus Darwin – Life gains complexityLamark – tied evolution to adaptation, gave a reason for the rise in complexityGave the mechanism for evolution: “use and disuse” MOSTLY DISPROVEN- It its used more, the trait will be stronger- Inheritance of acquired characteristics Lecture 2 (September 3) Darwin’s BackgroundHis voyage on the HMS Beagle:- Studied local geography, observed geographic adaptations, and collected specimens- Observed same sort of specimens in different places with different adaptations- Returned to England to develop his theory privately (1844)- Wallace wrote Darwin with the same ideas and they published together (1858)His Theory1. All present life is related through descent with modification from common ancestors2. Natural selection is the mechanism for evolutionObservation: Species produce more offspring than environment can support- Many die early, and because of limited recourses Observation: variation is heritable- Artificial selection leads to dramatic differences (ex: wild cabbage)Inference: individuals with helpful traits survive and leave more offspring than othersInference: adaptations accumulate over timeLecture 3 (September 5)What is NOT in Darwin’s theory1. Origin of life2. How variation arises3. How inheritance works4. Why variation still exists5. Sudden changes in fossil records6. Source of totally new charactersEvidence in support of his theory1. Direct observation of natural selection (ex: balloon flower bug, antibiotic resistant bacteria)2. Fossil recorda. Old fossils may lack present groups or may be extinct3. Homology – similarity in form as a result of a common ancestora. Evolutionary trees are based on shared homologous structuresb. Vestigial structures – ancestral homologous structures that aren’t useful anymore(ex: blind salamander)c. Developmental homologies (ex: embryos)d. Cellular/molecular homologies – universal genetic code and similarities of cells, DNA, proteins and genomes4. Convergence – natural selection chooses characteristics that are best for environmenta. Similar structures throughout the world (ex: cactuses in different deserts)b. Different ancestors, same characteristics (ex: flying squirrel/ sugar glider)5. Biogeography – distribution of speciesLecture 4 (September 8)Genes, Mutations, and InheritanceDarwin- Continuous variation in species- Accumulation of differences in offspringMendel & DeVries- Discrete genetic factors in individuals- No blending or accumulation- Importance of mutationsSutton-Boveri- Chromosome theory of inheritancePhenotypic variation is mostly genetic- Discrete variation Single gene locus, 2+ alleles, genotype determines phenotype- Quantitative variation Phenotype made by additive effects of 2+ loci (ex: skin color)- Complex gene interactions make for more heritable variation (epistasis)- Variation can be influenced by environment (epigenetics)Mutation: ultimate source of variation *in cells that make gametes* - Point mutation – makes new alleles- Chromosomal alterations – deletions, duplications, translocation- Duplicated genes can mutate into new alleles (which can expand the genome)Sexual reproduction increases genetic diversity- Sexual recombination – independent assortment, crossing over, fertilization- Recessive alleles (harmful or adaptive) can hide in heterozygotes Hardy-Weinburg and MicroevolutionThe population evolvesPopulation: individuals in the same somewhat isolated area breeding and making fertile offspringPopulations differ in genetic make-upGene pool: all alleles of all genes in the population“Fixed alleles” are homozygous for everyoneGenotypic frequency: % of each genotype in the populationAllelic frequency: % of each allele in the population*Genotypic and Allelic frequencies are usually different for a population*Microevolution – Change in the genetic make- up of a population- Due to natural selection of individual phenotypes- This is what Darwin observed on his voyageLecture 5 (September 10)Hardy-Weinburg Principle – IF there is random sexual reproduction in a large population, then the next generation will NOT changeConditions: (if these are met, every generation will have the same genotypic ratios)1. NO mutations2. NO natural selection3. NO gene flow4. Large population5. Random matingp2 +2pq + q2 =1 p+q=1 p=dominant allele q=recessive allelep2= frequency of homozygous dominant genotypeq2= frequency of homozygous recessive genotype2pq= frequency of heterozygous genotypeAlways check for Hardy-Weinburg, but IF you can assume H-W, then you can determine the genetic make-up of the population.Hardy-Weinburg lets us detect microevolution (used as a null hypothesis)- Compare expected H-W ratios with actual ratios- If H-W does not equal the actual ratios, then the population is evolving- Could be adaptive, adaptively neutral, or maladaptiveLecture 6 (September 12)Mechanisms of Evolution – (natural selection, genetic drift, gene flow)Natural selection – acts non-randomly on the phenotypes of individuals- Changes allelic and genotypic frequencies of the population- Population adapts to environment (ex: DDT resistance)Genetic Drift – changes in gene frequency due to random events- Small population size has more dramatic drifts- Often reduces diversity by eliminating or fixing alleles- Allelic frequency can vary widely with each generation- Founder effect – a few founders start a new isolated population Unrepresentative of the original population Over time there will be significant genetic drift- Bottleneck effect – event that drastically cuts the population size Some alleles may be lost,


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TAMU BIOL 112 - Exam 1 Study Guide

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