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Darwin’s Theory of Evolution Darwin Presents his Case Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006.

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Presentation on theme: "Darwin’s Theory of Evolution Darwin Presents his Case Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006."— Presentation transcript:


2 Darwin’s Theory of Evolution Darwin Presents his Case Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006

3 What do oranges and Butterball turkeys have to do with EVOLUTION? (Answers to come in this slide show!) THINK ABOUT IT

4 EVIDENCE OF EVOLUTION: 1.________________ 2.________________ 3. _______________ 4. _______________ 5. _______________ 6. _______________ 7. _______________ Fossil record Geographic Distribution Homologous structures Embryology DNA See Natural selection happen Artificial selection

5 A theory is a ____________, _______, explanation of phenomena that have occurred in the natural world, like the theory of __________________, ________, and _____________. well-supportedtestable gravitational attraction cell theoryatomic theory Isn’t evolution just a theory?

6 _________________ is found naturally in all populations GENETIC VARIATION

7 7. See Natural Selection Driving force for evolution Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable (genetic variation) During the struggle for resources, strongest survive & reproduce (natural selection) copyright cmassengale

8 Darwins idea from Malthus …….. _____________________ _ means that members of each species must ________ for food, space, and other __________. STRUGGLE FOR EXISTANCE COMPETE RESOURCES

9 WHAT IS DARWIN’S THEORY? Some organisms in a ________ are ________ to survive. Natural Selection population less likely


11 ____________________________ suggests that each species has ___________, with ________, from other species over time. This idea suggests that all living species are ____________________, and that all species, living and extinct, share a _________________. WHAT IS DARWIN’S THEORY? DESCENT WITH MODIFICATION DESCENDEDCHANGES RELATED TO EACH OTHER COMMON ANCESTOR

12 12 Common Descent with Modification Idea that organisms change with time, diverging from a common form This is what Caused evolution of new species

13 13 Descent With Modification Takes Place Over Long Periods of Time Natural Selection Can Be Observed As Changes In –Ecological Niches (their role in society) –Body Structures –Habitats (where they live) copyright cmassengale

14 14 Descent With Modification Species Today Look Different From Their Ancestors Each Living Species Has –Descended –With Changes –From Other Species –Over Time copyright cmassengale

15 15 Descent With Modification copyright cmassengale

16 16 Descent With Modification Implies –All Living Organisms Are Related –Single Tree of Life DNA, Body Structures, Energy Sources Common Descent –All Species, Living & Extinct, Were Derived From Common Ancestors copyright cmassengale

17 17 Natural Variation and Artificial Selection Abandoned The Idea That Species Were Perfect & Unchanging Observed Significant Variation in All Species Observed Observed Farmers Use Variation To Improve Crops & Livestock Called Selective Breeding copyright cmassengale

18 ARTIFICIAL SELECTION WORKS In artificial selection, ____________ provides the _________ through _________ and _________________ and ______________ those traits that they find ______. NATURE variation mutation sexual reproduction humans select useful EX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.

19 Breeds of Dogs Chihuahua – bred from Techichi of Mexico by Mayans, had religious significance Saint Bernard – bred by monks around 1050 A.D. to rescue travelers of mountain passes in the Swiss Alps between Italy and Switzerland Irish Wolfhound – bred in Ireland to hunt wolves and elk Dachshund – bred in Germany as early as the 15 th century to hunt badgers SLIDE FROM: BIOLOGY by Miller and Levine; Prentice Hall Publishing©2006

20 What do oranges and Butterball turkeys have to do with EVOLUTION? THINK ABOUT IT

21 This is what a butterball turkey and a naval orange have in common. They have been artificially selected and sometimes genetically modified.

22 22. Major Problem in Darwin’s Theory No mechanism (the how) to explain natural selection How could favorable variations be transmitted to later generations? With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was found copyright cmassengale

23 23 Evidence of Evolution Key Concept Darwin Argued That Living Things Have Been Evolving On Earth For Millions of Years. Evidence For This Process Could Be Found In: 1.The Fossil Record 2.The Geographical Distribution of Living Species 3.Homologous Structures of Living Organisms 4.Similarities In Early Development

24 How Do We Know Evolution Happens? The Fossil Record – ______ are the _______ _________________ found in layers of rock in the Earth. Fossils of ancient organisms remains

25 How Do We Know Evolution Happens? The layers of rock tell the history of the _____, while the _____ found within the rock tell a history of ___. The fossils are thought to be the ________ as the rock they are found in. Earthfossils life same age

26 Sea level Sedimentary rocks form in horizontal layers. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers. As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. Movement of Earth’s Crust Section 15-2 Fish die in the ocean and are covered in sediment. Over time and under increasing pressure, the remains becomes fossilized Earthquakes and volcanoes cause uplifting of the layers of the Earth, taking the fossils along Fossils of marine fish found on the mountain- sides of southwest Wyoming, which at one time was covered by an inland sea

27 TRANSITIONAL FOSSILS HAVE BEEN FOUND Scientific American; Dec 2005; Vol 293; p

28 Geographic distribution of Fossils of similar species Fossils of similar species have been found in different areas. Body structure is similar enough to suggest they were related and could have once been the same species.

29 Figure 15–14 Geographic Distribution of Living Species Section 15-3 Beaver NORTH AMERICA Muskrat Capybara SOUTH AMERICA Coypu Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara Beaver and capybara are ______________ _______ living in very ________ environments, while beaver and musk-rat are _______________ _______ living in a ______ environment. Differences between beaver and capybara show _________ evolution, while similarities between beaver and muskrat show __________ evolution. Differences between _____________ muskrat and coypu show _________ evolution, while similarities between ______________ capybara and coypu show ___________ evolution. closely-related species different distantly-related species similar divergent convergent closely-related divergent distantly-related convergent

30 If Darwin’s theory is correct you would expect to find ____________ yet _______________ living in a Geographic region as they spread into nearby habitats and evolve. (development of traits suited to their particular environment) different species closely related That’s EXACTLY what we do see!

31 When a single species or small group of species has evolved through ___________________ into diverse forms that live in different ways = _________________________________ ___ natural selection adaptive radiation OR divergent evolution Ex: Galápagos finches It is called Divergent evolution because they all started with a common ancestor and diverged or radiated out into different species from there.

32 REMEMBER THE GALAPAGOS TORTOISES Image from: BIOLOGY by Miller and Levine; Prentice Hall Publisher©2006 Little vegetation Long necks Lots of vegetation Short necks Intermediate vegetation Intermediate necks Tortoises adapted to different habitats as they spread from the mainland to the different islands. = DIVERGENT EVOLUTION = ADAPTIVE RADIATION

33 GALAPAGOS FINCHES The _____ of Galapagos finches have ______ to eating a _____ of _____. beaks adapted varietyfoods

34 If Darwin’s theory is correct you would also expect to find _______________ living in ________ geographic regions but similar habitats becoming ________ as they adapt to ______________. far apart different species more alike That’s EXACTLY what we do see! similar ecosystems

35 Sometimes different organisms evolve in different places or at different times but in ____________________ environments…and end up looking very similar. Process by which unrelated organisms come to resemble each other = _______________________ converge means come together or become more alike. ecologically similar convergent evolution

36 This is the opposite of divergent evolution. In divergent evolution, species were diverging and becoming more different from each other, BUT HERE, they are adapting to similar environments even though they are not living together and become more alike. They LOOK similar because their environments are similar even if they aren’t in the same place!

37 Whales and sharks have a _____ body design even though they are very _______ organisms (one is a fish; the other, a mammal) because they have _________________ to living in a _____ environment. = CONVERGENT EVOLUTION similar different independently adapted similar

38 Whales are closely related to wolves, but don’t look or act much like them = divergent evolution Whales are distantly related to sharks, but look and act more like them = convergent evolution Conclusion: The pressure of the environment drives evolution

39 How fast does evolution operate? fossil.jpg If biological change is at a slow pace, it is called ____________. gradualism Darwin believed evolution happened slowly over a long time

40 Fossil record shows evolution happens more in _____. Pattern of a long stable period interrupted by a brief period of more rapid change =____________ Punctuated Equilibrium bursts

41 Punctuated equilibrium is any sudden, rapid change in a species and can be genetic (mutation) or the result of other causes, such as huge and sudden changes in the environment that result in more rapid changes in the organism changes

42 Gradualism and Punctuated Equilibrium Gradualism and punctuated equilibrium are two ways in which the evolution of a species can occur. A species can evolve by only one of these, or by both. Scientists think that species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.

43 43 Evolutionary Time Scales Long time scale events that create and destroy species. Macroevolution: Long time scale events that create and destroy species. copyright cmassengale

44 44 Microevolution: Short time scale events (generation- to-generation) that change the genotypes and phenotypes of populations Evolutionary Time Scales copyright cmassengale

45 Homologous Body Structures – Structures, like the limbs of vertebrates, look very _______, but are made from the __________, because they are made from the same clump of _____________ cells in the _______. same bones embryo undifferentiated Image from: different

46 4. _____________________ Image from: HOMOLOGOUS Structures

47 47 Homologous Body Structures Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure May Differ In Form or Function Limb Bones Develop In Similar Patterns Arms, Wings, Legs, Flippers

48 48 Homologous Body Structures If you look at these organisms DNA you will see structures That Have Different Mature Forms…. But Develop From The Same Embryonic Tissues Strong Evidence That All Four-Limbed Animals With Backbones Descended, With Modification, From A Common Ancestor Help Scientist Group Animals

49 TurtleAlligatorBirdMammal Ancient lobe-finned fish Homologous Body Structures Section 15-3

50 4. Homologous Body Structures – Some _______________________ are _______ and have no useful function even though they are still present, like ________in whales and boa constrictors, or a ____ and ________________in humans. homologous body structures vestigial hipbones tail cecum (appendix)

51 Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a _____. In humans the cecum is shrunken and unused. It is our _________ appendix cecum

52 Why grow a tail and then lose it? HUMAN EMBRYO _________________ Tail disappears at has a tail at 4 weeks about 8 weeks tail

53 WHY DOES EVOLUTION MATTER NOW? There is a natural variation in populations of peppered moths. ________________ ___________________ 7.____________________________ EX: Peppered Moths Can see Natural selection happen Typica form - lighter Carbonaria form - darker Typica Carbonaria

54 Skinks are a type of lizard. In some species, legs have become so small they _______ ______ in walking. Why would an organism possess organs ___ ________________? One explanation: The ________ is present to make the organ, but _________________ through ______________. If the organ is not vital to survival, then natural selection would cause its elimination. no longer function gene code change over timefunction has been lost little or no function with

55 55 Homologous Body Structures Not All Serve Important Functions –Vestigial Organs Appendix In Man Legs On Skinks

56 Humans have many other nonfunctional vestigial genes called ________________. EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are ___________. PSEUDOGENES nonfunctional

57 57 Similarities In Early Development Embryonic Structures Of Different Species Show Significant Similarities Embryo – early stages of vertebrate development

58 5. _____________________ ________ of many animals with back- bones are very similar. Similarities in Embryology Embryos Image from:

59 It is clear that the same groups of _____________ cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all _______ from a _______________. undifferentiated evolved common ancestor Image from:

60 The ___________ form was the predominant form in England _____________________________. Around the middle of the 19 th century the ______ form began to appear. It was first reported in By % of the moths in Manchester were the ____ variety. In recent years, the burning of cleaner fuels and Clean Air regulations has reduced the pollution there and the ______ colored moths have increased in numbers. light colored prior to the Industrial Revolution darker dark lighter

61 ____________________________ EX: Changes in disease-causing microbes that produce new organisms and __________. _______ ___ __________________________ You Can see Natural selection happen Bird flu Antibiotic-resistant tuberculosis HIV new diseases

62 62 Evolution of pesticide resistance in response to selection

63 63 Evidence for Evolution – Evolution Observed Evolution of drug-resistance in HIV

64 Types of Selection Disruptive- P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Disruptive Selection.wmv P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Disruptive Selection.wmv Stabilizing- P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Stabilizing Selection.wmv P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Stabilizing Selection.wmv Directional- P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Directional Selection.wmv P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Directional Selection.wmv

65 TODAY we can understand how evolution works better than Darwin ever could because of our knowledge about ____________ and ________ genes DNA

66 Because members of a population interbreed, they share a common group of genes called a ___________ A gene pool consists of ____________ present in a population, including all the different _________. GENE POOL ALL the genes alleles

67 Sample Population 48% heterozygous black 36% homozygous brown 16% homozygous black Frequency of Alleles allele for brown fur allele for black fur The ____________________ is the number of times that an allele occurs in the gene pool compared to the occurrence of other alleles in the gene pool. relative frequency Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006

68 RELATIVE FREQUENCY is often expressed as a __________________. EX: In this population Dominant B allele (black) = 40% Recessive b allele (brown) = 60% percentage Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006

69 RELATIVE FREQUENCY has _________ to do with whether an allele is ______________ or _____________ In this population, the recessive allele is more frequent. DOMINANT RECESSIVE Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006 NOTHING

70 IN GENETIC TERMS __________________ is any change in the relative frequency of alleles in a population If the relative frequency of the B allele in this mouse population changed over time to 30%, the population is evolving. EVOLUTION Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006

71 _______________________IS THE MAJOR SOURCE OF VARIATION IN POPULATIONS, but it does _______ change the __________________ of alleles in population! SEXUAL REPRODUCTION NOT relative frequency Shuffling a deck of cards can shuffle to produce many different hands, but doesn’t change the number of kings or queens in the deck.

72 EX: A population of normally brown lizards. Mutations produce new color choices. If red lizards are more visible to predators, they might be less likely to survive. ____________________ on single-gene frequencies can lead to changes in ____________________ and thus to EVOLUTON NATURAL SELECTION Bird image from: Chart from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006 ALLELE FREQUENCIES

73 Natural selection can affect the distribution of phenotypes in 3 ways: ______________________ DIRECTIONAL selection STABILIZING selection DISRUPTIVE selection

74 DIRECTIONAL SELECTION Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006 Individuals at _____________ of the curve have higher fitness than individuals in middle or at other end. Graph shifts as some individuals fail to survive at one end and succeed and reproduce at other ONE END Low mortality, high fitness High mortality, low fitness KEY Food becomes scarce.

75 Beak size varies in a population Birds with bigger beaks can feed more easily on harder, thicker shelled seeds. Suppose a food shortage causes small and medium size seeds to run low. Birds with bigger beaks would be selected for and increase in numbers in population. EXAMPLE OF DIRECTIONAL SELECTION

76 STABILIZING SELECTION Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006 Individuals in _____________ of the curve have higher fitness than individuals at either end Graph stays in same place but narrows as more organisms in middle are produced. CENTER

77 Key Percentage of Population Brightness of Feather Color Selection against both extremes keep curve narrow and in same place. Section 16-2 Low mortality, high fitness High mortality, low fitness Stabilizing Selection Male birds use their plumage to attract mates. Male birds in the population with less brilliant and showy plumage are less likely to attract a mate, while male birds with showy plumage are more likely to attract a mate. Male birds with showier, brightly- colored plumage also attract predators, and are less likely to live long enough to find a mate. The most fit, then, is the male bird in the middle-- showy, but not too showy. STABILIZING SELECTION Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006

78 Human babies born with low birth weight are less likely to survive. Babies born too large have difficulty being born. Average size babies are selected for. EXAMPLE OF STABILIZING SELECTION

79 DISRUPTIVE SELECTION Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006 Individuals at _____________ of the curve have higher fitness than individuals in middle. Can cause graph to split into two. Selection creates __________________PHENOTYPES EXTREMES TWO DISTINCT

80 Suppose bird population lives in area where climate change causes medium size seeds become scarce while large and small seeds are still plentiful. Birds with bigger or smaller beaks would have greater fitness and the population may split into TWO GROUPS. One that eats small seeds and one that eats large seeds. EXAMPLE OF DISRUPTIVE SELECTION

81 In a small population this random change in allele frequency based on chance is called _________________ GENETIC DRIFT Genetic drift can occur when a _______ group of individuals colonizes a _____habitat. small new

82 Individuals may carry alleles in ______________ relative frequencies than in the larger population. The population they “found” will be different from the parent population... not through natural selection but by _________ different chance

83 A situation in which allele frequencies change as a result of the migration of a small subgroup of the population = _________________ FOUNDER EFFECT Graph from BIOLOGY by Miller and Levine; Prentice Hall Publshing©2006

84 HARDY-WEINBERG PRINCIPLE states that allele frequency in a population will remain __________ unless one or more ________ cause the frequency to __________. In a situation in which allele frequencies remain constant ( = _________________ ) populations will NOT EVOLVE! constant Genetic equilibrium factors change

85 5 CONDITIONS REQUIRED TO MAINTAIN GENETIC EQUILIBRIUM FROM GENERATION TO GENERATION 1. _________________________ 2. _________________________ 3. _________________________ 4. _________________________ 5. _________________________ Must be random mating Population must be large No movement in or out No mutations No natural selection

86 86 Review copyright cmassengale

87 87 Darwin's Theory 1.Individual Organisms In Nature Differ From One Another. Some Of This Variation Is Inherited 2.Organisms In Nature Produce More Offspring Than Can Survive, And Many Of These Offspring Do No Reproduce copyright cmassengale

88 88 Darwin's Theory 3.Because More Organisms Are Produced Than Can Survive, Members Of Each Species Must Compete For Limited Resources 4.Because Each Organism Is Unique, Each Has Different Advantages & Disadvantages In The Struggle For Existence copyright cmassengale

89 89 Darwin's Theory 5.Individuals Best Suited To Their Environment Survive & Reproduce Successfully – Passing Their Traits To Their Offspring, maximizing their fitness. 6.Species Change Over Time and become increasingly adapted over long periods. Natural Selection Causes Changes That May Eventually Lead To New Species copyright cmassengale

90 90 Darwin's Theory 7.Species Alive Today Have Descended With Modifications From Species That Lived In The Past 8.All Organisms On Earth Are United Into A Single Tree Of Life By Common Descent copyright cmassengale

91 Concept Map Section 15-3 includes Evidence of Evolution Physical remains of organisms Common ancestral species Similar genes which is composed ofwhich indicateswhich implies The fossil record Geographic distribution of living species Homologous body structures Similarities in early development

92 PBS EVOLUTION VIDEO CLIPS Isn’t Evolution Just a Theory? QuickTime Who was Charles Darwin? QuickTime How Do we Know Evolution Happens? QuickTime How Does Evolution Really Work? QuickTime |QuickTime Why Does Evolution Matter Now? QuickTime Why is Evolution Controversial Anyway? QuickTime

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