2 17–1 The Fossil Record A. Fossils and Ancient Life The fossil record provides evidence about the history of life on earth. It also shows how different groups of organisms have changed over time
3 17–1 The Fossil Record How Fossils Form Most fossils form in sedimentary rock. It is formed when exposure to rain, heat, wind and cold breaks down clayAs layers of sediment build up over time, dead organisms may also sink to the bottom and become buriedConditions are right, the remains may be kept intact
4 17–1 The Fossil Record C. Interpreting Fossil Evidence 1. Relative Dating- the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock (estimate age of fossils)2. Radioactive Dating- scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains
5 17–1 The Fossil RecordD. Geologic Time ScaleEras2. Periods
6 Comparing Relative and Absolute Dating of Fossils Section 17-1Compare/Contrast TableComparing Relative and Absolute Dating of FossilsCan determineIs performed byDrawbacksRelative DatingAbsolute DatingAge of fossil with respect to another rock or fossil (that is, older or younger)Age of a fossil in yearsComparing depth of a fossil’s source stratum to the position of a reference fossil or rockDetermining the relative amounts of a radioactive isotope and nonradioactive isotope in a specimenImprecision and limitations of age dataDifficulty of radio assay laboratory methodsGo to Section:
7 Figure 17-2 Formation of a Fossil Section 17-1Figure 17-2 Formation of a FossilWater carries small rock particles to lakes and seas.Dead organisms are buried by layers of sediment, which forms new rock.The preserved remains may later be discovered and studied.Go to Section:
8 Figure 17-5 Geologic Time Scale Section 17-1(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTimePermianCarboniferousDevonianSilurianOrdovicianCambrian290 – 245363–290410–363440–410505–440544–505QuarternaryTertiaryCretaceousJurassicTriassic1.8–present65–1.8145–65208–145245–208Vendian650–544Go to Section:
9 Figure 17-5 Geologic Time Scale Section 17-1(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTimePermianCarboniferousDevonianSilurianOrdovicianCambrian290 – 245363–290410–363440–410505–440544–505QuarternaryTertiaryCretaceousJurassicTriassic1.8–present65–1.8145–65208–145245–208Vendian650–544
10 Figure 17-5 Geologic Time Scale Section 17-1(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTime(millions of years ago)EraPeriodTimePermianCarboniferousDevonianSilurianOrdovicianCambrian290 – 245363–290410–363440–410505–440544–505QuarternaryTertiaryCretaceousJurassicTriassic1.8–present65–1.8145–65208–145245–208Vendian650–544
11 17–2 Earth’s Early History A. Formation of EarthEarth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water
12 17–2 Earth’s Early History The First Organic MoleculesOrganic molecules would have been able to be constructed but the oxygen in atmosphere was to reactive and would destroy any organic molecules that formed
13 17–2 Earth’s Early History C. How Did Life Begin?1. Formation of Microspheres- protection that allowed for the growth of organic molecules2. Evolution of RNA and DNA- still unanswered but scientists are searching
14 17–2 Earth’s Early History Free OxygenThe rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration
15 17–2 Earth’s Early History Origin of Eukaryotic CellsThe endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms
16 Figure 17-12 Endosymbiotic Theory ChloroplastPlants and plantlike protistsAerobic bacteriaAncient ProkaryotesNuclear envelope evolvingPhotosynthetic bacteriaMitochondrionPrimitive Photosynthetic EukaryoteAnimals, fungi, and non-plantlike protistsAncient Anaerobic ProkaryotePrimitive Aerobic EukaryoteGo to Section:
17 17–2 Earth’s Early History F. Sexual Reproduction and MulticellularityA few hundred million years after the evolution of sexual reproduction, evolving life forms crossed to developing multicellular organisms from single celled (unicellular) organisms
18 17–3 Evolution of Multicellular Life Precambrian Time- life existed only in the seaB. Paleozoic Era- rich with evidence of many types of marine lifeMesozoic Era- increasing dominance of dinosaurs, appearance of flowering plantsD. Cenozoic Era- mammals evolved adaptations that allowed them to live in various environments, on land, water and air
19 Geologic Time Scale with Key Events Section 17-3EraPeriodTime(millions of years ago)Key EventsCenozoicMesozoicPaleozoicPrecambrianTimeQuaternaryTertiaryCretaceousJurassicTriassicPermianCarboniferousDevonianSilurianOrdovicianCambrian1.8–present65–1.8145–65208–145245–208290–245363–290410–363440–410505–440544–505650–544Glaciations; mammals increased; humansMammals diversified; grassesAquatic reptiles diversified; flowering plants; mass extinctionDinosaurs diversified; birdsDinosaurs; small mammals; cone-bearing plantsReptiles diversified; seed plants; mass extinctionReptiles; winged insects diversified; coal swampsFishes diversified; land vertebrates (primitive amphibians)Land plants; land animals (arthropods)Aquatic arthropods; mollusks; vertebrates (jawless fishes)Marine invertebrates diversified; most animal phyla evolvedAnaerobic, then photosynthetic prokaryotes; eukaryotes, then multicellular life
20 17–4 Patterns of Evolution A. Mass Extinctions- dinosaursB. Adaptive Radiation- species evolved into several different forms that live in different waysC. Convergent Evolution- unrelated organisms come to resemble one another
21 17–4 Patterns of Evolution D. Coevolution- process by which two species evolve in response to changes in each other over timeE. Punctuated Equilibrium- patterns of long, stable periods interrupted by brief periods of more rapid changeGradualism- patterns of slow, gradual change
22 17–4 Patterns of Evolution F. Developmental Genes and Body Plans- changes in developmental genes, revealing major news about evolution of life
23 Flowchart Species Go to Section: that are Unrelated Related form in underunderininInter-relationshiopsSimilar environmentsIntense environmental pressureSmall populationsDifferent environmentscan undergocan undergocan undergocan undergocan undergoCoevolutionConvergent evolutionExtinctionPunctuated equilibriumAdaptive radiationGo to Section:
24 Section 15-1A Trip Around the WorldWhile on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises.
25 1. On a sheet of paper, list five animals that you have encountered in the past two days. 2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.)3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.
26 B. Darwin’s Observations 1. Patterns of Diversity 15–1 The Puzzle of Life’s DiversitySection 15-1A. Voyage of the BeagleB. Darwin’s Observations1. Patterns of Diversity2. Living Organisms and Fossils3. The Galápagos IslandsC. The Journey Home
27 Giant Tortoises of the Galápagos Islands Pinta Island Intermediate shellHood IslandSaddle-backed shellPinta Island Intermediate shell
29 My, How You’ve Changed!Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about.
30 1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.
31 2. In the second column, list your acquired characteristics 2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument.3. Which of the items in your lists do you think you might pass on to your children? Explain your answer
32 A. An Ancient, Changing Earth 1. Hutton’s Theory of Geological Change 15–2 Ideas That Shaped Darwin’s ThinkingA. An Ancient, Changing Earth1. Hutton’s Theory of Geological Change2. Lyell’s Principles of Geology
33 15–2 Ideas That Shaped Darwin’s Thinking B.Lamarck’s Theory of Evolution1. Tendency Toward Perfection2. Use and Disuse3. Inheritance of Acquired Traits4. Evaluating Lamarck’s TheoryC.Population Growth
34 Hutton’s Theory of Geological Change In 1975, geologist James Hutton proposed that layers of rock form very slowly. Some rocks are moved up by forces beneath the Earth’s surface, others are buried. Resulting rocks, mountains, and valleys are then shaped by a variety of natural forces-including rain, heat and cold temperatures
35 Lyell’s Principles of Geology Lyell’s work explained how awesome geological features could be built up or torn down over long periods of time.His work influenced Darwin in two ways:If the earth could change overtime, might life change as well?He realized that it must have taken many, many years, earth must be very old
36 Movement of Earth’s Crust As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed.When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers.New sediment is then deposited above the exposed older rock surface.Sedimentary rocks form in horizontal layers
37 Lamarck’s Theory of Evolution 1. Tendency Toward Perfection He proposed that all organisms are continually changing and acquiring features that help them live more successfully in their environment
38 2. Use and DisuseHe proposed that organisms could alter the size or shape of particular organs by using their bodies in new ways.Conversely, if a winged animal did not use its wings (ex. of disuse) the wings would decrease in size over generations and finally disappear
39 3. Inheritance of Acquired Traits Lamarck thought that acquired characteristics could be inheritedBy this reasoning, if you spent much of your life lifting weights to build muscles, your children would inherit big muscles, too.
40 4. Evaluating Lamarck’s Theory He was incorrect in many waysLamarck, like Darwin, did not know how traits are inherited or that behavior has no effect on its inheritable characteristicsOne of first to develop scientific theory of evolution and realize that organisms are adapted to their environment
42 15–3 Darwin Presents His Case A. Publication of On the Origin of SpeciesDarwin(1859)proposed a mechanism for evolution called natural selectionContinuous for millions of years and continues in all living thingsOthers strongly opposed
43 15–3 Darwin Presents His Case B. Natural Variation and Artificial SelectionNatural variation is the differences among individuals of a species, is found in all types of organismsArtificial Selection occurs through a technique called selective breeding, that would determine which individuals to use for breeding based on the natural variation that was found
44 15–3 Darwin Presents His Case C.Evolution by Natural SelectionThe Struggle for Existence- means that members of each species compete regularly to obtain food, living space, an other necessities of life
45 15–3 Darwin Presents His Case C. Evolution by Natural Selection2. Survival of the FittestFitness- the ability of an individual to survive and reproduce in its specific environmentAdaptation- is any inherited characteristics that increase an organism’s chance of survival
46 15–3 Darwin Presents His Case C. Evolution by Natural Selection2. Survival of the FittestIndividuals that are better suited to their environment-that is, with high levels of fitness-survive and reproduce most successfully
47 15–3 Darwin Presents His Case C. Evolution by Natural Selection2. Survival of the FittestOver time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in it’s environment
48 15–3 Darwin Presents His Case C. Evolution by Natural SelectionDescent With ModificationEach living species has descended, with changes, from other species over time
49 15–3 Darwin Presents His Case D. Evidence of Evolution1. The Fossil Recordprovided evidence that living things have been evolving for millions of years.Sometimes fossil records includes similar, intermediate forms of a group of organisms that together suggest gradual modification over time
50 Evidence of Evolution includes The fossil record Geographic distribution of living speciesHomologous body structuresSimilarities in early developmentwhich is composed ofwhich indicateswhich implieswhich impliesPhysical remains of organismsCommon ancestral speciesSimilar genes
51 D. Evidence of Evolution 2. Geographic Distribution of Living SpeciesAnimals living under similar ecological conditions, were exposed to similar pressures of natural selectionBecause of these similar selection pressures, different animals ended up evolving certain striking features in common
52 Figure 15–14 Geographic Distribution of Living Species BeaverMuskratBeaver and MuskratCoypuCapybaraCoypu and Capybara
53 D. Evidence of Evolution 3. Homologous Body Structuresstructures that have different mature forms and functions but develop from the same embryonic tissues
54 Figure 15–15 Homologous Body Structures TurtleAlligatorBirdMammalsTypical primitive fish
55 D. Evidence of Evolution 4. Similarities in Early Developmentearly stages, or embryos, of many animals with backbones are so similar that they can be hard to tell apart
56 E. Summary of Darwin’s Theory Organisms in nature differ, some variation is inheritedSurvival of the fittestNatural SelectionVariation
57 1. Make a list of physical traits that you think are influenced by genes. Then, write next to each trait whether you have the trait or not (e.g., a widow’s peak) or whether there are many variations of the trait (e.g., hair color).
58 2. Are most of the traits you listed clear-cut or are they mostly traits that have many variations? Which traits in your list are difficult to categorize?
59 3. Compare your list with that of another student 3. Compare your list with that of another student. Did he or she think of any traits that you missed? Why do you think some traits are clear-cut, while others are not?
60 16–1 Genes and Variation A. Darwin’s Ideas Revisited Without an understanding of heredity, Darwin was unable to explain two important factors. First, he did not know the source of the variation that was so central to his theory. Second, he could not explain how inheritable traits were passed from one generation to the next.
61 16–1 Genes and Variation B. Gene Pools is the combined genetic information of all the members of a particular population
62 16–1 Genes and Variation C. Sources of Genetic Variation Mutations- is any change in a sequence of DNAGene Shuffling- occurs during the production of gametes (23 chromosomes in sperm and 23 in egg=46 Zygote)Crossing over- exchange of genetic material between chromosomes
63 16–2 Evolution as Genetic Change C. Genetic DriftIn small, populations, individuals that carry a particular allele may leave more descendants than other individuals, just by chance. Over time, a series of chance occurrences of this type can cause an allele to become common in a population
64 16–2 Evolution as Genetic Change D. Evolution Versus Genetic EquilibriumRandom MatingEnsures that each individual has an equal chance of passing on it’s alleles
65 16–2 Evolution as Genetic Change D. Evolution Versus Genetic EquilibriumLarge PopulationImportant in maintaining genetic equilibriumGenetic drift has less effect on large populations
66 16–2 Evolution as Genetic Change D. Evolution Versus Genetic EquilibriumNo Movement Into or Out of the PopulationKeep gene pool together and separate of other populations
67 16–2 Evolution as Genetic Change D. Evolution Versus Genetic EquilibriumNo Mutations
68 16–2 Evolution as Genetic Change D. Evolution Versus Genetic Equilibrium5. No Natural Selection
70 Sample of Original Population Founding Population AFounding Population B
71 Sample of Original Population Descendants Founding Population AFounding Population B
72 Country Cousin/City Cousin What happens when a population or group of living things is divided into two separate groups in two separate environments? To understand what goes on, think about someone who lives in another part of the United States or in another country.
73 1. Make a list of everyday things that this person encounters that you don’t. For example, does he or she eat different kinds of food? Does he or she live in a climate different from yours?2. All humans are the same species. What might happen if groups of humans were separated for millions of years in very different environments, such as those you have just described?
74 16–3 The Process of Speciation A. Isolating MechanismsAs new species evolve, populations become reproductively isolated from each other1. Behavioral Isolation- two populations are capable of interbreeding, but differences in courtship rituals
75 2. Geographic Isolation- two populations are separated by geographic barriers such as rivers, mountains, or bodies of water3. Temporal Isolation- two or more species reproduce at different times (orchid in the rainforest)
76 16–3 The Process of Speciation B. Testing Natural Selection in Nature1. Variation- Grant’s concluded that there is a great deal of variation of inheritable traits among the Galopagos finches2. Natural Selection- when food for finches was scarce, individuals with the largest beaks were more likely to survive3. Rapid Evolution- changes in beaks occurred over decades instead of thousands of years
77 16–3 The Process of Speciation C. Speciation of Darwin’s Finches1. Founders Arrive2. Separation of Populations3. Changes in the Gene Pool4. Reproductive Isolation5. Ecological Competition6. Continued Evolution
78 16–3 The Process of Speciation C. Speciation of Darwin’s Finches1. Founders ArriveOnce they arrived on one of the island, they managed to survive and reproduce
79 16–3 The Process of Speciation C. Speciation of Darwin’s Finches2. Separation of PopulationsSpecies crossed islands
80 16–3 The Process of Speciation C. Speciation of Darwin’s FinchesChanges in the Gene PoolOver time natural selection would have caused that population to evolve larger beaks, forming a separate population
81 16–3 The Process of Speciation C. Speciation of Darwin’s FinchesReproductive IsolationGene pools of the two bird populations remain isolated from each other
82 16–3 The Process of Speciation C. Speciation of Darwin’s FinchesEcological CompetitionOvertime, species evolve in a way that increases the differences between them
83 16–3 The Process of Speciation C. Speciation of Darwin’s FinchesContinued EvolutionOver many generations, it produced the 13 finch species found there today
84 Reproductive Isolation results fromIsolating mechanismswhich includeBehavioral isolationTemporal isolationGeographic isolationproduced byproduced byproduced byBehavioral differencesDifferent mating timesPhysical separationwhich result inIndependently evolving populationswhich result inFormation of new species