Môn Sinh học - Chapter 22: Descent with modification: A darwinian view of life - Part A: darwin & natural selection

Ch. 22 Warm-UpWhat do you remember about Charles Darwin and his scientific ideas?According to Campbell, what is the definition of “evolution”?Chapter 22Descent with Modification:A Darwinian View of LifePart A: Darwin & Natural SelectionWhat you must know:How Lamarck’s view of the mechanism of evolution differed from Darwin’s.The role of adaptations, variation, time, reproductive success, and heritability in evolution.Descent with ModificationTheme:Evolutionary change is based on the interactions between populations & their environment which results in adaptations (inherited characteristics) to increase fitnessEvolution = change over time in the genetic composition of a populationHistorical Process of ScienceAristotle: life-forms arranged on scale on increasing complexity (scala naturae)Aristotle 384-322 B.C. Old Testament - Creationism: Earth ~6000 years old; perfect species individually designed by God Natural theology: discovering Creator’s plan by studying nature; to classify natureLinnaeus: founder of taxonomy; binomial nomenclatureDomain – Kingdom – Phylum – Class – Order – Family - Genus – Species (Dear King Philip Came Over For Good Spaghetti)Domains = Bacteria, Archaea, EukaryaClassification based on anatomy & morphologyCarolus Linnaeus1707-1778Cuvier:Paleontologist – studied fossilsDeeper strata (layers) - very different fossils from current lifeOpposed idea of evolutionCatastrophism – catastrophe destroyed many living species, then repopulated by immigrant speciesGeorge Cuvier(1769-1832)Formation of sedimentary strata with fossilsHutton / Lyell:Gradualism = geologic change results from slow & gradual, continuous process Uniformitarianism = Earth’s processes same rate in past & present  therefore Earth is very oldSlow & subtle changes in organisms  big changeCharles Lyell1797-1875James Hutton1726-1797Lamarck:Published theory of evolution (1809)Use and Disuse: parts of body used  bigger, stronger (eg. giraffe’s neck)Inheritance of Acquired Characteristics: modifications can be passed onImportance: Recognized that species evolve, although explanation was flawedJean-Baptiste Lamarck1744-1829Malthus:More babies born than deathsConsequences of overproducing within environment = war, famine, disease (limits of human pop.)Struggle for existenceThomas Malthus(1766-1834)Charles Darwin (1809-1882)English naturalist1831: joined the HMS Beagle for a 5-year research voyage around the worldCollected and studied plant and animal specimens, bones, fossilsNotable stop: Galapagos IslandsHMS Beagle (1831-1836)15Galapagos Islands16Darwin’s Finch CollectionThe birds were all about the same size, but the shape and size of the beaks of each species were different.18GiantTortoiseThe vice-governor of the Galapagos Islands told Darwin that he could tell which island a particular tortoise came from by looking at its shell.19Darwin waited 30 years before he published his ideas on evolutionAlfred Russell Wallace – published paper on natural selection first (1858)Charles Darwin (1859): On the Origin of Species by Means of Natural SelectionMechanism for evolution is Natural SelectionDarwin didn’t use “evolution”, but rather “descent with modification”“On the Origin of Species by Means of Natural Selection”By Charles Darwin(1859)Adaptations enhance an organism’s ability to survive and reproduceEg. Desert fox - large ears, arctic fox - small earsOverproduction of offspring leads to competition for resourcesTherefore, if humans can create substantial change over short time, nature can over long time.Natural SelectionArtificial SelectionNature decides“Man” decidesWorks on individualSelective breedingInbreeding occurseg. beakseg. dalmationsKey Ideas of Natural Selection:Competition for limited resources results in differential survival.Evolutionary Fitness: Individuals with more favorable phenotypes more likely to survive and produce more offspring, and pass traits to future generationsIf environment changes or individuals move to new environment, new adaptations and new species may arise.Populations evolve, not individuals.Discovery Video: Charles DarwinPBS: What Darwin Never KnewVideo Clip: 20:18 – 31:27