History of Evolutionary ThoughtPowerPoint PresentationSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27The Wallace LineSlide 29Slide 30History of Evolutionary ThoughtI. Early Ideas in Evolutionary BiologyA. Plato’s notion of the type1. Existence of an ideal form—’’eidos”- Still the basis of naming and classification-visible world was a manifestation of that form with imperfections2. “fixity of species” -ideal form does not change -very prevalent way of thinking early in time-idea that change did not happen-species were created the way we see them.B. Scala Naturae or the Great Chain of Being-Aristotle1. Progression from most complex to least complex-every organism is ordered in relation to man2. Organisms are unchanging since they were created in perfect form-change would imply imperfection in the original creation3. Impossible for new forms to have arisen since creation or existing forms to have gone extinct.C. Early Natural Science focused on cataloging and describing species1. Carolus Linnaeus published Systema Naturae in 1735-developed modern classification scheme that we still use today-strict believer in the Fixity of forms -binomial namesHistory of Evolutionary ThoughtII. Discovering a World in Flux (late 18th century)A. Comparative Biology--Georges Cuvier 1. “Unity of Structure”-each species had its own harmony of parts-species are discrete entities2. Groups of species have common harmonies-common harmonies extended to extinct species-first scientist to acknowledge extinct speciesB. Organic Mutability1. Evidence that plants and animals were not constant in form-species could change through artificial selection-tremendous amount of variation could be harbored in a single stock.2. Gilbert White (1780) -different breeds of pigeons traced back to Rock Dove-many diverse forms can arise from a single stock-artificial selection can be used to create different breedsC. Principles of Geology-Lyell in 18341. Calculated extinction rates from fossil record-extinction rates were relatively constant from layer to layer-why aren’t all species found today not represented in oldest strata?-extinction is a fact -different kinds of organisms lived on earth at different times.-Changes in earth’s geology caused some extinctions2. Periods of major extinctions correlated with -process of “selection” was obviously eliminating species that were unfit for new environmental conditionsD. Jean-Baptiste de Lamarck (1744-1829)1. Philosophie Zoologique in 18092. Inheritance of acquired characters-Use and disuse alter form during an individual’s life-Organisms changeform in response to changing environment. -Such acquired charactersare passed on to offspring. Earliest explanationof evolutionary changeE. Species selection versus Individual Selection1. Selection among species-more fit species survived, less fit species went extinct. THIS IS WRONG. More fit individuals are more likely to go one and pass the traits. 2. Evolution was a differential sorting of chance variations among species3. Idea of selection operating on the INDIVIDUAL - One of the key contributions made by Darwin’s evolutionary theoryHistory of Evolutionary ThoughtIII. Charles Darwin (1809-1882)-Born February 12th-British, educated at Cambridge-Naturalist on British navyexpedition on the Beagle1831-1836-published On the OriginOf Species by Means ofNatural Selection in 1859A. Voyage of the Beagle1. Observations made in the Galápagos Islands-mockingbirds fromdifferent islands lookedlike different species-same was true for tortoises and finches-bills were adapted to fitwell with foods availableGalapágos Islands--Giant tortoisesCactus finchLarge ground finchSharp beaked ground finchSharp beaked ground finchdrinking booby bloodWoodpecker finchMedium ground finch -- Geospiza fortisMolecular phylogeny of Darwin’s Finches (Petren et al. 2005)Ancestral finchB. Darwin’s Evolutionary Theory1. Individuals within species are variable.2. Certain of these variants are passed on to offspring.3. In every generation, more offspring are produced than can survive.(Thomas Malphus’s idea) 4. Differential survival and reproduction-only those individuals with favorable variations live to reproduce and contribute offspring to the next generation-These individuals are NATURALLY SELECTEDHence, the mechanism of evolutionary change.C. Darwinian Fitness1. Fitness is the currency of natural selection-the ability of an individual to survive and reproduce in its environment-traits that confer higher fitness are ADAPTATIONSimages.fws.govHistory of Evolutionary ThoughtIV. Alfred Russel Wallace (1823-1913)A. Wallace also proposed Natural Selection as the mechanism for evolutionary change1. Sent his paper to Darwin in June of 1858-paper by Wallace and paper by Darwin were both read at annual meeting of Linnean Society in London later that year-Darwin published The Origin of Species in November 18592. Wallace had formulated his ideas of natural selection based upon variation he observed among animals and plants on different islands in Malay archipelagoThe Wallace LineSeparation of Asian and Australian flora and fauna in as little at 15 miles!History of Evolutionary ThoughtV. Darwin & Wallace’s ContributionsA. Effects on our view of change1. Selection among individuals, not species2. Gradual change- fueled by the idea that Earth is billions of years old). Provided enough time for the evolution of species. -Selection works on small differences among individuals.3. Role of ecological differentiation (differences in habitat shape color)4. Role of sexual selection5. Natural selection could result in new species-as the frequency of new forms increases, this could lead to the formation of a very different new species.Lamarck’s view -species arise independently Complexity increases through timeDarwin’s view-species arise through common ancestry Complexity increases through timescala naturaeDescent with