Evolution. Evidence supporting evolution Fossil record shows change over time Anatomical record comparing body structures homology & vestigial structures

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  • Evolution

  • Evidence supporting evolutionFossil recordshows change over timeAnatomical recordcomparing body structureshomology & vestigial structuresembryology & developmentMolecular recordcomparing protein & DNA sequencesArtificial selectionhuman caused evolution

  • Fossils help decipher lifes historyLaetoliHyracotheriumLayers of rock contain fossils new layers cover older onescreates a record over timefossils show evidence for past lifeover a long period of time

  • Fossils tell a storythe Earth is oldLife is oldLife on Earth has changed

  • Evolution of birdsTodays organisms descended from ancestral speciesFossil of Archaeopteryxlived about 150 myalinks reptiles & birds

  • Land MammalWhere are the intermediate fossils?Ocean MammalWhale evolution

  • Vestigial organsHind leg bones on whale fossilsWhy would whales have pelvis & leg bones if they were always sea creatures?Dolphin embryoHind limb buds

  • Evolution from sea to land2006 fossil discovery of early tetrapod4 limbsMissing link from sea to land animalsichthyostega

  • Anatomical recordAnimals with different structures on the surfaceBut when you look under the skinIt tells an evolutionary story of common ancestors

  • Compare the bonesHomologous Structures

  • But dont be fooled by theseAnalogous structureslook similar on the outsideSame functiondifferent structure & developmenton the insidedifferent originno evolutionary relationshipSolving a similar problem with a similar solution

  • Analogous structuresDolphins: aquatic mammalFish: aquatic vertebrateboth adapted to life in the seanot closely related

  • Convergent evolution3 groups with wingsDoes this mean they have a recent common ancestor?Flight evolved 3 separate times evolving similar solutions to similar problems

  • Convergent evolution led to mimicryWhy do these pairs look so similar?Monarch malepoisonousViceroy maleedible

  • Comparative embryologyDevelopment of embryo tells an evolutionary story similar structures during development

  • Molecular recordComparing DNA & protein structureeveryone uses the same genetic code! DNAcompare common genescompare common proteinsnumber of amino acids different from human hemoglobin

  • Building family treesClosely related species are branches on the tree coming from a common ancestor

  • Evolution: the source of Earths biodiversityBiological evolution: genetic change in populations of organisms across generationsNatural selection: reproductive fitness

  • Understanding evolution is vital

    to understand how organisms adapt to their environment and change over time. It is needed for ecology, a central component of environmental science.Relevant for agricultural, medicine, pesticide resistance, environmental health

  • Genetic variationGenes of better-adapted individuals will be more prevalent than those of less well-adapted individuals in future generations.Adaptive trait (adaptation): a trait (characteristic) that promotes reproductive successMutations: accidental changes in DNA that may be passed on to the next generationNon-lethal mutations provide the genetic variation on which natural selection acts.Sexual reproduction, which involves recombination (the mixing of parental genes), also leads to variation.

  • functioning: beaks in honeycreepersEvidence of natural selection is everywhere

  • How do we know natural selection can change a population?we can recreate a similar processevolution by human selectionArtificial selectiondescendants of wild mustard

  • Artificial selectionHumans create the change over timedescendants of the wolf

  • Artificial selection

  • Artificial Selection gone bad!Unexpected consequences of artificial selectionPesticide resistanceAntibiotic resistance

  • Insecticide resistance

    Spray the field, butinsecticide didnt kill all individuals- variationresistant survivors reproduceresistance is inheritedinsecticide becomes less & less effective

  • Evolution generates biodiversityBiological diversity (biodiversity): an areas sum total of all organisms The diversity of species Their genes Their populationsTheir communities

  • Evolution: A PreviewAdaptation of a population to a new environment may lead to a new speciesDarwins ObservationsMore offspring than neededPopulation size is about the sameIndividuals differSome variation is inherited

  • Evolution: A PreviewAdaptation of a population to a new environment may lead to a new speciesDarwins ObservationsMore offspring than neededPopulation size is about the sameIndividuals differSome variation is inheritedYou wont see this unless you are prepared to see it

  • ExpeditionsAlfred Wallace

    Brazil Malay Peninsula 8 years 125,000 animal specimensAccess to remote places to make biodiversity collections

  • Age of the EarthUniformitariansPresent mechanisms hold for the pastErosion & uplifting = mountainsCatastrophistsA few violent events occur suddenly

  • Age of the EarthUniformitariansEarth must be oldCatastrophistsEarth can be youngNot an evolutionary question(Bishop Usher: October 22, 4004 BC )

  • Malthus & Populationpopulation sizetimeTendency to rise beyond numbers that can be supported by the environment

    Reduced by disease, war1776-1834

  • Evolutionary QuestionsDo species change?If so, how?Evolution: Change through time

  • Jean-Baptist LamarckVariability within species

    Trend of increasing complexity in speciesOutstanding NaturalistObservations

  • Lamarcks Theory of EvolutionSpecies change in response to a changed environmentSpecies can change by useChanges are passed onTheory of Acquired CharacteristicsPublished in 1809

  • Lamarcks GiraffeOriginal short necked ancestorKeeps stretching neck to reach leaves higher up on treeand stretchingand stretching until neck becomes progressively longer

  • Darwins GiraffeOriginal group exhibits variation in neck lengthNatural selection favors longer necks: better chance to get higher leaves.

    Favored character passed on to next generationAfter many, many generations the group is still variable, but shows a general increase in neck length

  • Lamarcks Contributions to the Development of Evolutionary TheoryPresented evidence that fossils were the remains of extinct animals.Occurrence of fossils suggested to Lamarck that profound changes had taken place during the history of life on earth.Proposed the hypothesis of evolution by the inheritance of acquired characteristics.

  • Lamarcks Theory of EvolutionLamarck had good dataIt is good common senseBut it isnt right

  • Theories in Lamarcks timeIf data support your theory, andYou cant think of an alternative theoryYour theory must be right

  • Theories TodayPoor theories are not discardedA poor theory can only be replaced by a better oneA subtle but important difference

  • Darwin (1809-1882)But Darwin relied on his own observationsGround work for the acceptance of evolution already done

    Many of the main ideas already known

  • Darwin: AccomplishmentAge 27: 5 year voyage completedAge 30: good travel book writtenMiddle age: natural history expertAge 50: Origins publishedLifetime = 20 books, 80 papers

  • Darwin: AttributesGifted experimentalistEquivalent of a millionaireQuiet & modest lifestyle

  • Darwin: AttributesTremendous energyGift of simplicityCourageousWrote so that the common person could read his works

  • Darwin: ChronologyCollege, but sporting setActive naturalist, collectorBeagle as companion to FitzroyGone for 5 years

  • DarwinSouth America = no rabbitsBut animals there were similar to rabbitsWhy no rabbits?Ancestors had to get there or they must have originated there

  • European Rabbit: Oryctolagus cuniculus

  • Mara:Dolichotis patagonum

  • DarwinStruck by similarities between the types of animals (Europe vs. South America)Found evidence of change in collections of fossils

  • Returned to EnglandMarried, ill healthDarwinLondon

  • Species in Darwins TimeWhat is a species?Each species created as a unique entitySpecies characteristics do not change

  • Species Variability?Rock Dove

  • Artificial SelectionI liked breeding pigeons!

  • Darwin's Ideas1837: Outline of ideas1842: Full set of notes1844: Book length manuscriptBut he didnt publish this ...

  • Why Did Darwin Wait?160 pages not enough?Another book, Vestiges of the History of Creation1856: Nagged by Lyell (geologist)1857: Wrote to Wallace (to get some facts)

  • Alfred Russel Wallace1823 - 1913

  • Wallace12 pages same basic conclusion as Darwin1858: Wrote sketch of his theory of evolutionSent to Darwin to be published

  • DarwinLinnean Society Presentation5 page summary of eventsPrevious Darwin letterWallaces 12 page letter

  • Result?No noticeDarwin produced book by 1859All copies sold on the first day10 years later: most scientists believe Darwins theory

  • Darwins Natural SelectionA few serious challengesIdeas languishedMid-20th century revivalWhy so long?Needed a mechanism: modern genetics

  • Darwins Observations & ConclusionsO1:Organisms produce more offspring than are needed for replacement

    O2:Population size stays about the same

    C1:There is competition for survival

  • Darwins Observations & ConclusionsO3:Natural resources are limited

    C2:Most adapted individuals leave mor