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1 Evolution Diversity of Life. 2 Nothing in biology makes sense EXCEPT in the light of evolution. Theodosius Dobzhansky Evolution Charles Darwin in later.

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Presentation on theme: "1 Evolution Diversity of Life. 2 Nothing in biology makes sense EXCEPT in the light of evolution. Theodosius Dobzhansky Evolution Charles Darwin in later."— Presentation transcript:

1 1 Evolution Diversity of Life

2 2 Nothing in biology makes sense EXCEPT in the light of evolution. Theodosius Dobzhansky Evolution Charles Darwin in later years

3 3 History of Evolutionary Thought

4 4 Early Ideas On Earths Organisms Aristotle believed species were fixed creations arranged by their complexity Aristotle believed species were fixed creations arranged by their complexity Idea lasted 2000 years Idea lasted 2000 years

5 5 Early Ideas On Earths Organisms Linnaeus – 1 st to group similar organisms and assign them Latin names Linnaeus – 1 st to group similar organisms and assign them Latin names Two word name (Genus species) Two word name (Genus species) Known as Binomial nomenclature Known as Binomial nomenclature

6 6 : Contributors to Darwins thinking included: Charles Lyell – uniformatarianismCharles Lyell – uniformatarianism Georges Cuvier – species extinction (Catastrophism)Georges Cuvier – species extinction (Catastrophism) Thomas Malthus – struggle for existenceThomas Malthus – struggle for existence

7 7 : Contributors to Darwins thinking included: James Hutton - GradualismJames Hutton - Gradualism John Baptiste Lamarck – Inheritance of acquired Characteristics and Law of Use and DisuseJohn Baptiste Lamarck – Inheritance of acquired Characteristics and Law of Use and Disuse Alfred Russel Wallace – organisms evolved from common ancestorsAlfred Russel Wallace – organisms evolved from common ancestors

8 8 Evolutionary Timeline

9 9 Catastrophism Idea proposed by George Cuvier Idea proposed by George Cuvier Studied fossil in sedimentary rock strata of Paris Studied fossil in sedimentary rock strata of Paris Found some species completely disappeared in more recent layers Found some species completely disappeared in more recent layers

10 10 Catastrophism Stated that species disappear due to a catastrophic event of the earths crust (volcano, earthquake…) Stated that species disappear due to a catastrophic event of the earths crust (volcano, earthquake…)

11 11 Huttons Theory of Geological Change James Hutton, 1795, Scottish geologist James Hutton, 1795, Scottish geologist Studied invertebrate fossils in Paris Museum Studied invertebrate fossils in Paris Museum Described The Geological Forces That Have Changed Life on Earth Over Millions of Years (erosion, earthquakes, volcanoes…) Described The Geological Forces That Have Changed Life on Earth Over Millions of Years (erosion, earthquakes, volcanoes…)

12 12 Huttons Theory of Geological Change Changes in Earths crust due to slow continuous processes Changes in Earths crust due to slow continuous processes Idea Known as Gradualism Idea Known as Gradualism

13 13 Charles Lyell Proposed theory of Uniformitarianism Proposed theory of Uniformitarianism Geological processes at uniform rates building & wearing down Earths crust Geological processes at uniform rates building & wearing down Earths crust Proposed that the Earth was millions of years instead of a few thousand years old Proposed that the Earth was millions of years instead of a few thousand years old

14 14 Principles of Geology Published by Lyell Just Before The Beagle Set Sail & read by Darwin Published by Lyell Just Before The Beagle Set Sail & read by Darwin Explained Geological Processes That Shaped The Earth Explained Geological Processes That Shaped The Earth Helped Darwin Understand Sea Shells In The Andes Mountains At 12,000+ Feet Helped Darwin Understand Sea Shells In The Andes Mountains At 12,000+ Feet –Expanded Earths Age

15 15 Lamarcks Theory of Evolution Jean-Baptiste Lamarck, 1809 Jean-Baptiste Lamarck, 1809 One Of First Scientists To Understand That Change Occurs Over Time One Of First Scientists To Understand That Change Occurs Over Time Stated that Changes Are Adaptations To Environment acquired in an organisms lifetime Stated that Changes Are Adaptations To Environment acquired in an organisms lifetime Said acquired changes were passed to offspring Said acquired changes were passed to offspring

16 16 Lamarcks Theory of Evolution Idea called Law of Use and Disuse Idea called Law of Use and Disuse If a body part were used, it got stronger If a body part were used, it got stronger If body part NOT used, it deteriorated If body part NOT used, it deteriorated

17 17 Lamarcks Theory of Evolution Inheritance of Acquired Characteristics Inheritance of Acquired Characteristics Proposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their Lifetime Proposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their Lifetime These Traits Could Then Be Passed On To Their Offspring These Traits Could Then Be Passed On To Their Offspring Over Time This Led To New Species Over Time This Led To New Species

18 18 Lamarcks Theory of Evolution Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them Blacksmiths & Their Sons (muscular arms) Blacksmiths & Their Sons (muscular arms) Giraffes Necks Longer from stretching) Giraffes Necks Longer from stretching)

19 19

20 20 Lamarcks Theory of Evolution Inheritance Of Acquired Traits Inheritance Of Acquired Traits –Traits Acquired During Ones Lifetime Would Be Passed To Offspring Clipped ears of dogs could be passed to offspring!

21 21 Lamarcks Theory of Evolution Tendency Toward Perfection Tendency Toward Perfection Organisms Are Continually Changing and Acquiring Features That Help Them Live More Successfully In Their Environment Organisms Are Continually Changing and Acquiring Features That Help Them Live More Successfully In Their Environment Example: Bird Ancestors Desired To Fly So They Tried Until Wings Developed Example: Bird Ancestors Desired To Fly So They Tried Until Wings Developed

22 22 Lamarcks Mistakes Lamarck Did NOT Know how traits were inherited (Traits are passed through genes) Lamarck Did NOT Know how traits were inherited (Traits are passed through genes) Genes Are NOT Changed By Activities In Life Genes Are NOT Changed By Activities In Life Change Through Mutation Occurs Before An Organism Is Born Change Through Mutation Occurs Before An Organism Is Born

23 23 Charles Darwin the Naturalist

24 24 Voyage of the Beagle Charles Darwin Born Feb. 12, 1809 Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Joined Crew of HMS Beagle, 1831 Naturalist Naturalist 5 Year Voyage around world 5 Year Voyage around world Avid Collector of Flora & Fauna Avid Collector of Flora & Fauna Astounded By Variety of Life Astounded By Variety of Life

25 25 A reconstruction of the HMS Beagle sailing off Patagonia. Darwins Voyage of Discovery

26 26 Darwin Left England in 1831 Darwin returned 5 years later in 1836

27 27 HMS Beagles Voyage

28 28 The Galapagos Islands Small Group of Islands 1000 km West of South America Small Group of Islands 1000 km West of South America Very Different Climates Very Different Climates Animals On Islands Unique Animals On Islands Unique »Tortoises »Iguanas »Finches

29 29 The Galapagos Islands Volcanic islands off the coast of South America Volcanic islands off the coast of South America Island species varied from mainland species & from island-to- island species Island species varied from mainland species & from island-to- island species Each island had long or short neck tortoises Each island had long or short neck tortoises

30 30

31 31 The Galapagos Islands Finches on the islands resembled a mainland finch Finches on the islands resembled a mainland finch More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had different types of beaks adapted to their type of food gathering Finches had different types of beaks adapted to their type of food gathering

32 32

33 33 Darwins Observations & Conclusions The Struggle for Existence

34 34 Voyage of the Beagle During His Travels, Darwin Made Numerous Observations And Collected Evidence That Led Him To Propose A Revolutionary Hypothesis About The Way Life Changes Over Time

35 35 Darwins Observations Patterns of Diversity were shown Patterns of Diversity were shown Unique Adaptations in organisms Unique Adaptations in organisms Species Not Evenly Distributed Species Not Evenly Distributed »Australia, Kangaroos, but No Rabbits »S. America, Llamas

36 36 Darwins Observations Both Living Organisms & Fossils collected Both Living Organisms & Fossils collected Fossils included: Fossils included: »Trilobites »Giant Ground Sloth of South America This species NO longer existed. What had happened to them?

37 37 Evidence for Evolution – The Fossil Record

38 38 Definition Evolution is the slow, gradual change in a population of organisms over time

39 39 Darwins Observations Left unchecked, the number of organisms of each species will increase exponentially, generation to generation In nature, populations tend to remain stable in size Environmental resources are limited

40 40 Darwins Conclusion Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals Only a fraction of offspring survive each generation Survival of the Fittest

41 41 Darwins Observations Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike. Much of this variation between individuals is inheritable.

42 42 Darwins Conclusion Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection

43 43 The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection)The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) New species evolveNew species evolve Darwins Theory of Evolution

44 44 Ideas That Shaped Darwins Thinking Thomas Malthus

45 45 Population Growth Thomas Malthus, 1798 Thomas Malthus, 1798 Economist Economist Observed Babies Being Born Faster Than People Were Dying Observed Babies Being Born Faster Than People Were Dying Population size limited by resources such as the Food Supply Population size limited by resources such as the Food Supply

46 46 The Struggle for Existence Malthus Influence: –High Birth Rates & Limited Resources Would Force Life & Death Competition Each Species Struggles For: –Food –Living Space –Resources

47 47 Population Growth Malthus Reasoned That If The Human Population Continued To Grow Unchecked, Sooner or Later There Would Be Insufficient Living Space & Food For Everyone Malthus Reasoned That If The Human Population Continued To Grow Unchecked, Sooner or Later There Would Be Insufficient Living Space & Food For Everyone Death Rate Will Increase To Balance Population & Food Supply Death Rate Will Increase To Balance Population & Food Supply

48 48 Population Growth Darwin Realized Malthuss Principles Were Visible In Nature Darwin Realized Malthuss Principles Were Visible In Nature Plants & Animals Produce Far More Offspring Than Can Be Supported Plants & Animals Produce Far More Offspring Than Can Be Supported –Most Die –If They Didnt – Earth Would Be Overrun

49 49 Darwins Theory of Evolution Organisms Change OverTime

50 50 Common Descent with Modification Darwin proposed that organisms descended from common ancestors Darwin proposed that organisms descended from common ancestors Idea that organisms change with time, diverging from a common form Idea that organisms change with time, diverging from a common form Caused evolution of new species Caused evolution of new species

51 51. Natural Selection Driving force for evolution Driving force for evolution During the struggle for resources, strongest survive & reproduce During the struggle for resources, strongest survive & reproduce Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable

52 52 Origin of Species Darwin Presents His Case

53 53 Publication of On The Origin of Species Upon His Return To England, Darwin Developed His Observations Into The Theory of Evolution Upon His Return To England, Darwin Developed His Observations Into The Theory of Evolution But He Did Not Publish For 25 Years – But He Did Not Publish For 25 Years –Why?

54 54 Publication of On The Origin of Species Darwin Knew That His Theory Would Be Extremely Controversial And Would Be Attacked Darwin Knew That His Theory Would Be Extremely Controversial And Would Be Attacked His Theory Challenged Established Religious & Scientific Beliefs, Particularly About The Creation Of Man His Theory Challenged Established Religious & Scientific Beliefs, Particularly About The Creation Of Man

55 55 Publication of On The Origin of Species He Refused To Publish Until He Received An Essay From Alfred Wallace He Refused To Publish Until He Received An Essay From Alfred Wallace –Fellow Naturalist –Independently Developed The Same Theory –After 25 Years, Someone Else Had Come To The Same Conclusions From Their Observations Of Nature

56 56 Wallaces Contribution Alfred Russel Wallace Independently came to same Conclusion as Darwin that species changed over time because of their struggle for existenceAlfred Russel Wallace Independently came to same Conclusion as Darwin that species changed over time because of their struggle for existence When Darwin read Wallaces essay, he knew he had to publish his findingsWhen Darwin read Wallaces essay, he knew he had to publish his findings

57 57 Publication of On The Origin of Species Darwin Presented Wallaces Essay & Some Of His Work At A Scientific Conference of the Linnaean Society in July of 1858 Darwin Presented Wallaces Essay & Some Of His Work At A Scientific Conference of the Linnaean Society in July of 1858 Then He Started On his book Origin of Species Then He Started On his book Origin of Species It Took Darwin 18 Months To Complete The Book It Took Darwin 18 Months To Complete The Book

58 58 Natural Variation and Artificial Selection Abandoned The Idea That Species Were Perfect & Unchanging Abandoned The Idea That Species Were Perfect & Unchanging Observed Significant Variation in All Species Observed Observed Significant Variation in All Species Observed Observed Farmers Use Variation To Improve Crops & Livestock Observed Farmers Use Variation To Improve Crops & Livestock Called Selective Breeding Called Selective Breeding

59 59 Natural Variation and Artificial Selection Natural Variation Natural Variation –Differences Among Individuals Of A Species Artificial Selection Artificial Selection –Selective Breeding To Enhance Desired Traits Among Stock or Crops

60 60 Natural Variation and Artificial Selection Key Concept: In Artificial Selection, Nature Provided The Variation Among Different Organisms, And Humans Selected Those Variations That They Found Useful

61 61

62 62 Origin of Species Concepts and Controversy

63 63 Evolution By Natural Selection Concepts The Struggle for Existence (compete for food, mates, space, water, etc.) The Struggle for Existence (compete for food, mates, space, water, etc.) Survival of the Fittest (strongest able to survive and reproduce) Survival of the Fittest (strongest able to survive and reproduce) Descent with Modification (new species arise from common ancestor replacing less fit species) Descent with Modification (new species arise from common ancestor replacing less fit species)

64 64 Survival of the Fittest Fitness –Ability of an Individual To Survive & Reproduce Adaptation –Inherited Characteristic That Increases an Organisms Chance for Survival

65 65 Survival of the Fittest Adaptations Can Be: – –Physical »Speed, Camouflage, Claws, Quills, etc. –Behavioral »Solitary, Herds, Packs, Activity, etc.

66 66 Survival of the Fittest Is Central To The Process Of Evolution Fitness Is Central To The Process Of Evolution Individuals With Low Fitness Individuals With Low Fitness –Die –Produce Few Offspring Survival of the Fittest AKA AKA Natural Selection

67 67 Survival of the Fittest Key Concept Over Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment

68 68 Natural Selection Cannot Be Seen Directly Cannot Be Seen Directly It Can Only Be Observed As Changes In A Population Over Many Successive Generations It Can Only Be Observed As Changes In A Population Over Many Successive Generations –Radiation –Fossil Record

69 69 Descent With Modification Takes Place Over of Time Takes Place Over Long Periods of Time Natural Selection Can Be As Changes In Natural Selection Can Be Observed As Changes In –Body Structures –Ecological Niches –Habitats

70 70 Descent With Modification Species From Their Ancestors Species Today Look Different From Their Ancestors Each Living Species Has Each Living Species Has –Descended –With Changes –From Other Species –Over Time

71 71 Descent With Modification

72 72 Descent With Modification Implies 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

73 73. Major Problem in Darwins Theory No mechanism to explain natural selection How could favorable variations be transmitted to later generations? With the rediscovery of Mendels work in the first half of the 20th century, the missing link in evolutionary theory was found

74 74 Opposition to Evolution The upheaval surrounding evolution began with Darwins publication of On the Origin of Species By Means of Natural Selection The debate continues nearly 150 years later

75 75 Theory of Evolution Today Supporting Evidence

76 76 Homologous Structures

77 77 Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development

78 78 Similarities in DNA Sequence

79 79 Evolution of pesticide resistance in response to selection

80 80 Evidence for Evolution – Evolution Observed Evolution of drug-resistance in HIV

81 81 Evidence for Evolution – Evolution Observed Selection against small guppies results in an increase in average size

82 82 Evolutionary Time Scales Long time scale events that create and destroy species. Macroevolution: Long time scale events that create and destroy species.

83 83 Microevolution: Short time scale events (generation- to-generation) that change the genotypes and phenotypes of populations Evolutionary Time Scales

84 84 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: –The Fossil Record –The Geographical Distribution of Living Species –Homologous Structures of Living Organisms –Similarities In Early Development

85 85 Fossil Record Earth is Billions of Years Old Earth is Billions of Years Old Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time

86 86 Geographic Distribution of Living Species Different Animals On Different Continents But Similar Adaptations To Shared Environments Different Animals On Different Continents But Similar Adaptations To Shared Environments

87 87 Homologous Body Structures Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure May Differ In Form or Function May Differ In Form or Function Limb Bones Develop In Similar Patterns Limb Bones Develop In Similar Patterns »Arms, Wings, Legs, Flippers

88 88 Homologous Body Structures Structures That Have Different Mature Forms But Develop From The Same Embryonic Tissues 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 Strong Evidence That All Four- Limbed Animals With Backbones Descended, With Modification, From A Common Ancestor Help Scientist Group Animals Help Scientist Group Animals

89 89 Homologous Body Structures

90 90 Homologous Body Structures Not All Serve Important Functions Not All Serve Important Functions –Vestigial Organs »Appendix In Man »Legs On Skinks

91 91 Similarities In Early Development Embryonic Structures Of Different Species Show Significant Similarities Embryonic Structures Of Different Species Show Significant Similarities Embryo – early stages of vertebrate development Embryo – early stages of vertebrate development

92 92 Human Fetus – 5 weeks

93 93 ChickenTurtle Rat

94 94 Review

95 95 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

96 96 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

97 97 Darwin's Theory 5. Individuals Best Suited To Their Environment Survive & Reproduce Successfully – Passing Their Traits To Their Offspring. 6. Species Change Over Time. Over Long Periods, Natural Selection Causes Changes That May Eventually Lead To New Species

98 98 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

99 99


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