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December 8, 2010

December 8, 2010. Notes - Chapter 15 Evolution HW. – outline Ch. 16 notes Chapter 15 and 16 due Thursday. Definitions. Evolution = change over time The process By Which Modern Organisms Have Descended From Ancient Organisms Theory

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December 8, 2010

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  1. December 8, 2010 Notes - Chapter 15 Evolution HW. – outline Ch. 16 notes Chapter 15 and 16 due Thursday

  2. Definitions • Evolution = change over time • The process By Which Modern Organisms Have Descended From Ancient Organisms • Theory • A Well Supported, Testable Explanation of Phenomena That Have Occurred In The Natural World

  3. 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

  4. Darwin’s Observations • Patterns of Diversity • Unique Adaptations • Species Not Evenly Distributed • Australia, Kangaroos but No Rabbits • S. America, Llamas

  5. Darwin’s Observations • Living Organisms & Fossils • Fossils • Resembled living organisms • Where Had These Species Gone? • How Were They Related To Living Species?

  6. The Galapagos Islands • Small Group of Islands 1000 km West of S. America • 3 Very Different Climates • Animals On Islands Unique to the island • Tortoises • Iguanas • Finches

  7. Who else? An Ancient, Changing Earth: Hutton & Lyell Helped Scientists Recognize That Earth Is Many Millions of Years Old, And The Processes That Changed Earth In The Past Are The Same Processes That Operate In The Present

  8. Hutton’s Theory of Geological Change • James Hutton • Described The Geological Forces That Have Changed The Earth Over Millions of Years • Sedimentary • Volcanic • Displacement • Erosion

  9. Lyell’s Principles of Geology • Explained Geological Processes That Shaped The Earth • Helped Darwin Understand Sea Shells In The Andes Mountains At 12,000+ Feet • Expanded Earth’s Age

  10. Lamarck’s Theory of Evolution • Jean-Baptiste Lamarck • One Of First Scientists To Understand That Change Occurs Over Time • Changes Are Adaptations To Environment • Almost On The Right Track, Almost

  11. Lamarck’s Theory of Evolution • Key Concept • Lamarck 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. Over Time This Led To New Species.

  12. Lamarck’s Theory of Evolution • Tendency Toward Perfection • Organisms Are Continually Changing and Acquiring Features That Help Them Live More Successfully In Their Environment • Bird Ancestors Desired To Fly So They Tried Until Wings Developed

  13. Lamarck’s Theory of Evolution • Use & Disuse • Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them • Giraffe’s Necks

  14. Lamarck’s Theory of Evolution • Inheritance Of Acquired Traits • Traits Acquired During Ones Lifetime Would Be Passed To Offspring (applies to ALL organisms) • Ex. If you spent much of your life building muscles then your offspring would inherit big muscles too!

  15. Lamarck’s Theory of Evolution • Lamarck’s Errors • Did Not Know About Inheritance of Traits • Genes Are Not Changed By Activities In Life • Change Through Mutation, Occurs Before An Organism Is Born

  16. Population Growth • Thomas Malthus • Economist • Observed Babies Being Born Faster Than People Were Dying • Population vs. Food Supply

  17. Population Growth • Key Concept • Malthus Reasoned That If The Human Population Continued To Grow Unchecked, Sooner or Later There Would Be Insufficient Living Space & Food For Everyone

  18. Population Growth • Darwin Realized Malthus’s Principles Were Visible In Nature. • Plants & Animals Produce Far More Offspring Than Can Be Supported. • Most Die • If They Didn’t – Earth Would Be Overrun

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

  20. Publication of “On The Origin of Species” • 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

  21. Publication of “On The Origin of Species” • He Refused To Publish Until He Received An Essay From Alfred Wallace • Fellow Naturalist • Independently Developed The Same Theory

  22. Natural Variation & Artificial Selection • Natural Variation • Differences Among Individuals Of A Species • Artificial Selection • Selective Breeding To Enhance Desired Traits Among Stock or Crops

  23. Natural Variation & Artificial Selection In Artificial Selection, Nature Provided The Variation Among Different Organisms, And Humans Selected Those Variations That They Found Useful

  24. Evolution By Natural Selectionhow does evolution occur? • The Struggle for Existence • Survival of the Fittest • Descent with Modification

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

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

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

  28. Survival of the Fittest • Fitness Is Core To The Process Of Evolution • Individuals With Low Fitness • Die • Produce Few Offspring Survival of the Fittest AKA Natural Selection

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

  30. Descent With Modification • Over Long Periods • Natural Selection Can Be Observed As Changes In • Body Structures • Ecological Niches • Habitats

  31. Descent With Modification • Species Today Look Different From Their Ancestors • Each Living Species Has • Descended • With Changes • From Other Species • Over Time

  32. 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

  33. Evidence of Evolution 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

  34. Fossil Record • Earth is Billions of Years Old • Fossils In Different Layers of Rock Showed Evidence Of Gradual Change Over Time

  35. Geographic Distribution of Living Species • Different Animals On Different Continents But SimilarAdaptations To Shared Environments

  36. Homologous Body Structures • Scientists Noticed Animals With Backbones Had Similar Bone Structure • May Differ In Form or Function • Arms, Wings, Legs, Flippers • Limb Bones Develop In Similar Patterns

  37. Homologous Body Structures • Homologous Structures • Structures That Have Different Mature Forms But Develop From The Same Embryonic Tissues • Shows Strong Evidence of A Common Ancestor

  38. Homologous Body Structures

  39. Homologous Body Structures • Not All homologous structures Serve Important Functions • Vestigial Organs • Appendix In Man • Legs On Skinks (type of lizard)

  40. Similarities In Early Development Chicken Turtle • Embryonic Structures Of Different Species Show Significant Similarities Rat Human

  41. REVIEW: Darwin's Theory • Individual Organisms In Nature Differ From One Another. Some Of This Variation Is Inherited • Organisms In Nature Produce More Offspring Than Can Survive, And Many Of These Offspring Do No Reproduce

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

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

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

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