2 WHO INFLUENCED DARWIN’S THINKING Figure 22.2Linnaeus (classification)Hutton (gradual geologic change)Lamarck (species can change)Malthus (population limits)Cuvier (fossils, extinction)Lyell (modern geology)Darwin (evolution, nutural selection)Mendel (inheritance)Wallace (evolution, natural selection)1750American RevolutionFrench RevolutionU.S. Civil War1800185019001795Hutton proposes his theory of gradualism.1798Malthus publishes “Essay on the Principle of Population.”1809Lamarck publishes his theory of evolution.1830Lyell publishes Principles of Geology.1831–1836Darwin travels around the world on HMS Beagle.Darwin begins his notebooks on the origin of species.1837Darwin writes his essay on the origin of species.1844Wallace sends his theory to Darwin.1858The Origin of Species is published.1859Mendel publishes inheritance papers.1865Image from: AP BIOLOGY by Campbell and Reece
3 Species are fixed (unchanging) BUT recognized similarities Image from:Aristotle- ( B.C.)Species are fixed (unchanging)BUT recognized similaritiesArranged life forms on a scale of increasing complexityscala natura- “scale of nature”
4 Binomial Nomenclature: Naming system that gives organisms a Image from:Founder of TAXONOMY-1735Science of grouping & namingSought to discover order in the diversity of life “for the greater glory of God”Each creature was special- NO evolutionary linkDevised classification system based on morphology (form and structure)( )Binomial Nomenclature: Naming system that gives organisms atwo part scientific name- Genus speciesStill used today
5 LINNAEUS’S SYSTEM Nested hierarchy Taxon = classification unit to which organisms are assignedEx:Panthera is a taxon at the genus levelMammalia is a taxon at the class level
6 Kidspiration by Riedell Image Sources: see end of show
7 Kingdom Phylum Class Order Family Genus Species Animalia Chordata Kids Prefer Cheese Over Fried Green SpinachKings Play Chess On Fat Green StoolsKing Phillip Cried Oh For Goodness Sake!KingdomPhylumClassOrderFamilyGenus SpeciesAnimaliaChordataMammaliaCarnivoraFelidaePantheraleo
8 GENUS = group of closely related species (Includes many kinds of bears)SPECIES = unique to each kind of bearGENUS = UrsusUrsus arctosUrsus maritimusUrsus americanis
9 Genus and species assignments provide 2 part scientific name Homo sapiensHomo sapiensImage from:
10 Modern Taxonomy has added more Kingdoms AND more levels (DOMAINS) Linneaus only used 2 kingdoms (Plants & Animals)Domains are larger than Kingdoms and are based on the differences in ribosomal RNA
11 Ideas that shaped Darwin’s thinking: George Cuvier – Father of PaleontologyANTI-EVOLUTONISTFossils are remains ofextinct life forms“CATASTROPHISM” -boundaries represent floods, droughts, etc. that destroyed many species living at that time
12 Ideas that shaped Darwin’s thinking: 1795 –James Hutton “GRADUALISM” Profound changes can resultfrom cumulative effect ofslow but continuousprocessesProposed that the Earth was shaped bygeological forces occurring over very longperiods of time, and is MILLIONS notTHOUSANDS of years old.
13 Ideas that shaped Darwin’s thinking: 1833-Charles Lyell Incorporated Hutton’s ideas into“UNIFORMITARIANISM”Geological processes thatshaped Earth are stilloperating at same rate.Darwin read his book on the Beagle voyage
15 Ideas that shaped Darwin’s thinking: Thomas Malthus (1798) Ideas that shaped Darwin’s thinking:Thomas Malthus (1798)wrote essay on population growthHuman suffering (disease, famine, homelessness, and war) are consequences to human population increasing faster than food and other resources
16 Ideas that shaped Darwin’s thinking: Jean Baptiste Lamarck (1744-1829) Ideas that shaped Darwin’s thinking:Jean Baptiste Lamarck ( )One of first scientists to recognizethat living things changed over timeand that all species were descendedfrom other species.1809- Published his ideas about “Inheritance of Acquired Characteristics” the year Darwin was born
17 INHERITANCE OF ACQUIRED CHARACTERISTICS The male fiddler crab uses itsfront claw to attract mates andward off predators.“USE or DISUSE” = Use it or lose itThrough repeated use, the frontclaw becomes larger.The fiddler passes on this acquired characteristic to its offspring
18 What’s wrong with Lamarck’s hypothesis? Lamarck didn’t know aboutgenes and how traits are inherited.Acquired traits are not passed on to offspringOr are they? New field of EPIGENETICS is exploring this
19 What’s right with Lamarck’s hypothesis? Lamarck was first todevelop a scientifichypothesis aboutevolution and recognizethat organisms areadapted to theirenvironment
20 Slide by Kim Foglia@ http://www.explorebiology.com/
21 Who Was Charles Darwin?In 1831, 22-year old Charles Darwin left England as naturalist aboard the HMS Beagle for 5 year voyage around the world.Mission: Chart the South American coastlineDarwin noticed plantsand animals were differentfrom those he knew in EuropeWrote thousands of pagesof observations andcollected vast number ofspecimens
23 Who Was Charles Darwin? Although animals on Galapagos resemble species on theSouth American mainland,many species were found nowhere else in the world = ENDEMIC
24 DARWIN’SFINCHESDarwin collected 14 species of finches and hypothesized that the Galapagos had be colonized by organisms from the mainland that had then diversified on the various
25 Who Was Charles Darwin?After Darwin returned to England in 1836, he spent years examining specimens he brought back from voyage and filling notebooks with his ideas.He did not rush to publish his ideas because theydisagreed with the fundamental scientific views of hisday.In 1844 he wrote an essay describing his ideas andasked his wife to publish it if he died.
26 In 1858 Alfred Russel Wallace, another Naturalist working in the West Indies,wrote an essay describing his work thatsummarized the same ideas Darwin hadbeen thinking about for 25 years!
27 Suddenly Darwin had incentive to publish the results of his work! On the Origin of Species by Means of Natural Selectionpresented evidenceand proposed amechanism for evolutionthat he calledNATURAL SELECTION
29 Isn’t evolution “just a theory”? In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence.The formal scientific definition of “theory” is quite different from the every day meaning.It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.
30 Isn’t evolution just a theory? In Science a theory is a well supported, testable explanation of phenomena that have occurred in the natural world.Example:Cell theoryAtomic theoryGravitational theory
31 VOCABADAPTATION- Any inherited characteristic that increases an organism’s chance of survival
32 WHAT IS DARWIN’S THEORY? OVERPRODUCTION of OFFSPRINGCapacity to over-reproduce seems characteristic of all species.
33 WHAT IS DARWIN’S THEORY? STRUGGLE FOR EXISTANCE meansthat members of each species mustcompete for food, space, andother resources.
34 WHAT IS DARWIN’S THEORY? GENETIC VARIATION is found naturally in all populationsImage from
35 WHAT IS DARWIN’S THEORY? Some organisms in a population are less likely to survive.
36 VOCABAbility of an individual to survive and reproduce in its specific environment = FITNESS
37 WHAT IS DARWIN’S THEORY? SURVIVAL OF THE FITTEST =Organisms which are better adaptedto their environment tend to producemore offspring than organisms withoutthose traits.
38 results in changes in the inherited characteristics of a population. WHAT IS DARWIN’S THEORY?Over time,NATURAL SELECTIONresults in changes in theinherited characteristics of a population.These changes increase aspecies’ fitness in its environment.How Does Evolution Really Work?
39 IMPORTANT TO REMEMBER ! POPULATIONS evolve NOT INDIVIDUALS. NATURAL SELECTION only works on heritable traits.A trait that is favorable in one environment may be useless or detrimental in another.
40 DESCENT WITH MODIFICATION WHAT IS DARWIN’S THEORY?DESCENT WITH MODIFICATIONsuggests that each species hasdescended with changesfrom other species over time.This idea suggests that all livingspecies are related to each otherand that all species, living and extinct,share a common ancestor.
41 What do oranges, broccoli and Butterball turkeys have to do What do oranges, broccoli andButterball turkeys have to dowith EVOLUTION?(Answers to come in this slide show!)THINK ABOUT IT
42 EVIDENCE OF EVOLUTION: ________________3. _______________4. _______________5. _______________6. _________________7. _______________Artificial selectionFossil recordGeographic DistributionAnatomical homologiesEmbryologyMolecular homologiesCan see Natural selection happen
43 ARTIFICIAL SELECTION WORKS Nature provides the variation through mutation and sexual reproduction andhumans select those traits that they findusefulEX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.
45 WE’VE DONE IT WITH ANIMALS If humans canselect forbeneficial traits,why can’t nature?If artificial selectioncan achieve so muchchange in relativelyshort time, why can’t major changes happen over thousands ofgenerations?
46 Now you know what broccoli and Butterball turkeys have to do with evolution!(Answers about oranges to come in this slide show!)THINK ABOUT IT
47 How Do We Know Evolution Happens? The Fossil Recordprovides evidence thatorganisms have changedover time.
48 If evolution has happened, we should be able to find evidence of evolution in the fossil record AND WE HAVE !BBC Tiktaalik video
49 Lots of TRANSITIONAL FOSSILS have been found Scientific American; Dec 2005; Vol 293; p
50 TIK-TAALIK Intermediate between fish and early tetrapods TIK-TAALIKIntermediate between fish and early tetrapodsFins have basic wrist bones and simple fingersEarliest fish with a neckDiscovered by Neil Shubin and Ted Daeschler in 2004
51 GEOGRAPHIC DISTRIBUTION = BIOGEOGRAPHY If Darwin’s theory is correct you would expect to find closely related yet different species living in ageographic region as they spread into nearby habitats and evolve.That’s EXACTLY what we do see!
52 The beaks of Galapagos finches have GALAPAGOS FINCHESThe beaks of Galapagos finches haveadapted to eating a variety of foods
54 If Darwin’s theory is correct you would also expect to find different species living in far apart geographic regionsbut similar habitats becoming more alike as they adapt to similar environments.That’s EXACTLY what we do see!
55 BOTH LIVE IN FOREST ECOSYSTEMS Adapted to similar environments, but evolved independently from different ancestors.SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North AmericanFLYING SQUIRRELS because its ancestors were marsupials.
56 Whales and sharks have a similar body design Whales and sharks have a similar body designeven though they are very different organisms(one is a fish; the other, a mammal)because they have independently adapted to living in a similar environment.= CONVERGENT EVOLUTION
58 EVOLUTION explains why certain characteristics in related species have anunderlying similarity.Section 15-3TurtleAlligatorBirdMammalAncient lobe-finned fish
59 amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid
60 VESTIGIAL ORGANSSome homologous structures are vestigial and have no useful function even though they are still present.Examples:Hipbones and pelvis in whales and boa constrictorsCecum (appendix) in humans Skink legs
61 Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a cecum.In humans the cecumis shrunken and unused.It is our appendix
62 EMBRYOLOGY Development of vertebrate embryos follows same path Image from:
63 Same groups of undifferentiated cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all evolved from a common ancestor.Image from:
64 Why grow a tail and then lose it? HUMAN EMBRYO has a tail at 4 weeks which disappears at 8 weeksPharyngeal pouchesbecome gills in fish,parts of throat/ears in humans
65 Nonfunctional legs in skinks Why would an organism possess organs without function?Why would an organism grow a part and then discard it?If organisms evolved from ancestors in which thatpart functioned, the gene code to make the part would still be there even though it doesn’t work.If the organ is not vital to survival, thennatural selection would not cause its elimination.
66 MOLECULAR HOMOLOGIESAll life forms share same genetic machinery (DNA & RNA)Universal genetic codeImportant genes share highly conserved sequences
67 Similarities in protein sequences suggests similarities in DNA Image from: Modern Biology by Holt, Rinehart, and Winston
69 Similarities in karyotypes suggest an evolutionary relationship Human- 46 chromosomes Chimpanzee- 48 chromosomesSimilarities in karyotypessuggest an evolutionary relationshipHuman:Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
70 Even differences show relatedness Human- 46 chromosomes Chimpanzee- 48 chromosomesEven differences show relatednessChimpanzees have 2 smaller chromosome pairs we don’t haveHumans have 1 larger chromosome pair (#2) they don’t have.Human:Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
71 PSEUDOGENES are vestigial genes. EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are nonfunctional.
72 Slide by Kim Foglia@ http://www.explorebiology.com/
73 Why does evolution matter now? EX: Changes in disease-causing microbes that produce new organisms and new diseases.____________________________________Can see Natural selection happenBird fluHIVAntibiotic-resistant tuberculosisWhy does evolution matter now?
74 Researchers have developed numerous drugs to combat HIV But using these medications selects for viruses resistant to the drugsPatientNo. 1Patient No. 2Percent of HIV resistant to 3TCPatient No. 3WeeksGraph from BIOLOGY by Campbell and Reece