2WHO 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
3Species 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”
4Binomial 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
5LINNAEUS’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
6Kidspiration by Riedell Image Sources: see end of show
7Kingdom 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
8GENUS = group of closely related species (Includes many kinds of bears)SPECIES = unique to each kind of bearGENUS = UrsusUrsus arctosUrsus maritimusUrsus americanis
9Genus and species assignments provide 2 part scientific name Homo sapiensHomo sapiensImage from:
10Modern 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
11Ideas 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
12Ideas 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.
13Ideas 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
15Ideas 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
16Ideas 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
17INHERITANCE 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
18What’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
19What’s right with Lamarck’s hypothesis? Lamarck was first todevelop a scientifichypothesis aboutevolution and recognizethat organisms areadapted to theirenvironment
20Slide by Kim Foglia@ http://www.explorebiology.com/
21Who 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
23Who Was Charles Darwin? Although animals on Galapagos resemble species on theSouth American mainland,many species were found nowhere else in the world = ENDEMIC
24DARWIN’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
25Who 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.
26In 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!
27Suddenly 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
29Isn’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.
30Isn’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
31VOCABADAPTATION- Any inherited characteristic that increases an organism’s chance of survival
32WHAT IS DARWIN’S THEORY? OVERPRODUCTION of OFFSPRINGCapacity to over-reproduce seems characteristic of all species.
33WHAT IS DARWIN’S THEORY? STRUGGLE FOR EXISTANCE meansthat members of each species mustcompete for food, space, andother resources.
34WHAT IS DARWIN’S THEORY? GENETIC VARIATION is found naturally in all populationsImage from
35WHAT IS DARWIN’S THEORY? Some organisms in a population are less likely to survive.
36VOCABAbility of an individual to survive and reproduce in its specific environment = FITNESS
37WHAT IS DARWIN’S THEORY? SURVIVAL OF THE FITTEST =Organisms which are better adaptedto their environment tend to producemore offspring than organisms withoutthose traits.
38results 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?
39IMPORTANT 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.
40DESCENT 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.
41What 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
42EVIDENCE OF EVOLUTION: ________________3. _______________4. _______________5. _______________6. _________________7. _______________Artificial selectionFossil recordGeographic DistributionAnatomical homologiesEmbryologyMolecular homologiesCan see Natural selection happen
43ARTIFICIAL 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.
45WE’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?
46Now you know what broccoli and Butterball turkeys have to do with evolution!(Answers about oranges to come in this slide show!)THINK ABOUT IT
47How Do We Know Evolution Happens? The Fossil Recordprovides evidence thatorganisms have changedover time.
48If evolution has happened, we should be able to find evidence of evolution in the fossil record AND WE HAVE !BBC Tiktaalik video
49Lots of TRANSITIONAL FOSSILS have been found Scientific American; Dec 2005; Vol 293; p
50TIK-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
51GEOGRAPHIC 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!
52The beaks of Galapagos finches have GALAPAGOS FINCHESThe beaks of Galapagos finches haveadapted to eating a variety of foods
54If 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!
55BOTH 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.
56Whales 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
58EVOLUTION explains why certain characteristics in related species have anunderlying similarity.Section 15-3TurtleAlligatorBirdMammalAncient lobe-finned fish
59amnion /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
60VESTIGIAL 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
61Most 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
62EMBRYOLOGY Development of vertebrate embryos follows same path Image from:
63Same 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:
64Why 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
65Nonfunctional 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.
66MOLECULAR HOMOLOGIESAll life forms share same genetic machinery (DNA & RNA)Universal genetic codeImportant genes share highly conserved sequences
67Similarities in protein sequences suggests similarities in DNA Image from: Modern Biology by Holt, Rinehart, and Winston
69Similarities 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.
70Even 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.
71PSEUDOGENES are vestigial genes. EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are nonfunctional.
72Slide by Kim Foglia@ http://www.explorebiology.com/
73Why 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?
74Researchers 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