BIOL 112 1ST Edition Exam 1 Study Guide Lectures 1 11 Lecture 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 random Views before Darwin 1600 s Aristotle s scala naturae nature ladder Medieval Biblical creationism and young earth ideas 1700 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 floods Hutton slow continuous processes produce geological features ex Grand Canyon Lyell uniformitarianism same as Hutton but believed in an old earth because processes are slow and constant Principles of Geology Erasmus Darwin Life gains complexity Lamark tied evolution to adaptation gave a reason for the rise in complexity Gave 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 Background His 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 Theory 1 All present life is related through descent with modification from common ancestors 2 Natural selection is the mechanism for evolution Observation 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 others Inference adaptations accumulate over time Lecture 3 September 5 What is NOT in Darwin s theory 1 2 3 4 5 6 Origin of life How variation arises How inheritance works Why variation still exists Sudden changes in fossil records Source of totally new characters Evidence in support of his theory 1 Direct observation of natural selection ex balloon flower bug antibiotic resistant bacteria 2 Fossil record a Old fossils may lack present groups or may be extinct 3 Homology similarity in form as a result of a common ancestor a Evolutionary trees are based on shared homologous structures b 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 genomes 4 Convergence natural selection chooses characteristics that are best for environment a Similar structures throughout the world ex cactuses in different deserts b Different ancestors same characteristics ex flying squirrel sugar glider 5 Biogeography distribution of species Lecture 4 September 8 Genes Mutations and Inheritance Darwin Continuous variation in species Accumulation of differences in offspring Mendel DeVries Discrete genetic factors in individuals No blending or accumulation Importance of mutations Sutton Boveri Chromosome theory of inheritance Phenotypic 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 Microevolution The population evolves Population individuals in the same somewhat isolated area breeding and making fertile offspring Populations differ in genetic make up Gene pool all alleles of all genes in the population Fixed alleles are homozygous for everyone Genotypic frequency of each genotype in the population Allelic 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 voyage Lecture 5 September 10 Hardy Weinburg Principle IF there is random sexual reproduction in a large population then the next generation will NOT change Conditions if these are met every generation will have the same genotypic ratios 1 2 3 4 5 NO mutations NO natural selection NO gene flow Large population Random mating p2 2pq q2 1 p q 1 p dominant allele q recessive allele 2 p frequency of homozygous dominant genotype q2 frequency of homozygous recessive genotype 2pq frequency of heterozygous genotype Always 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 maladaptive Lecture 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 therefore there is more genetic drift Reduced heterozygosity The maladaptive genes often survive with the bottleneck effect Gene Flow move alleles in and out of a population Includes migration of adults dispersal of gametes seeds spores and larvae Ex between streams