1 Evolution Diversity of Life

Evolution biological change by which descendants come to differ from their ancestors. biological change by which descendants come to differ from their ancestors. Central theme in all fields of Biology Central theme in all fields of Biology 2

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

4 History of Evolutionary Thought

5 Early Ideas On Earth’s Organisms Linnaeus – 1 st to group similar organisms – classification system Linnaeus – 1 st to group similar organisms – classification system This system reflected evolutionary relationships among species. This system reflected evolutionary relationships among species. Species- Group of organisms that are closely related Species- Group of organisms that are closely related

Theories of Geological Change 6

Age of Earth was a key issue in early debates of evolution. Age of Earth was a key issue in early debates of evolution. Common view- neither Earth nor species that lived on it had changed. Common view- neither Earth nor species that lived on it had changed. 7

8 Catastrophism Stated that species disappear due to a catastrophic event of the earth’s crust (volcano, earthquake…) Stated that species disappear due to a catastrophic event of the earth’s crust (volcano, earthquake…)

9 Hutton’s Theory of Geological Change Changes in Earth’s crust due to slow continuous processes Changes in Earth’s crust due to slow continuous processes Idea Known as Gradualism Idea Known as Gradualism

10 Charles Lyell Proposed theory of Uniformitarianism Proposed theory of Uniformitarianism Geological processes at uniform rates building & wearing down Earth’s crust Geological processes at uniform rates building & wearing down Earth’s 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

11 Charles Darwin the Naturalist

12 Lamarck’s Mistakes Lamarck Did NOT Know how traits were inherited Lamarck Did NOT Know how traits were inherited 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

13 Voyage of the Beagle Charles Darwin Joined Crew of HMS Beagle, 1831 Joined Crew of HMS Beagle, 1831 Naturalist Naturalist 5 Year Voyage around world 5 Year Voyage around world

Charles Darwin Astounded By Variety of Life Astounded By Variety of Life First person to present evidence that species changed over time.-Lots of data First person to present evidence that species changed over time.-Lots of data 14

15 A reconstruction of the HMS Beagle sailing off Patagonia. Darwin’s Voyage of Discovery

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

17 The Galapagos Islands Volcanic islands off the coast of South America- different climates Volcanic islands off the coast of South America- different climates Island species varied from mainland species & from island-to- island species Island species varied from mainland species & from island-to- island species

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Adaptation The variation among species on the islands made Darwin realize species may be able to adapt to their surroundings. The variation among species on the islands made Darwin realize species may be able to adapt to their surroundings. A feature that allows an organism to better survive and reproduce in it’s environment. A feature that allows an organism to better survive and reproduce in it’s environment. 19

20 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

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Darwin Found fossil evidence of species changing over time Found fossil evidence of species changing over time Found fossils of marine organisms up in the mountains- Evidence of gradualism. Found fossils of marine organisms up in the mountains- Evidence of gradualism. 22

23 Evidence for Evolution – The Fossil Record

Origin of Species Darwin’s ideas of natural selection being the driving force of evolution. Darwin’s ideas of natural selection being the driving force of evolution. Published in 1856 Published in

25 Darwin’s Conclusion Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection

26 Natural Variation and Artificial Selection Artificial Selection Artificial Selection –Selective Breeding To Enhance Desired Traits Among Stock or Crops

27 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)

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

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

30 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

31 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

32 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

33 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

34 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

35 Descent With Modification

36 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

37. Major Problem in Darwin’s Theory No mechanism 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

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

39 Theory of Evolution Today Supporting Evidence

40 Homologous Structures

41 Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development

42 Similarities in DNA Sequence

43 Evolution of pesticide resistance in response to selection

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

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

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

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

48 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

49 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

50 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

51 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

52 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

53 Homologous Body Structures

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

55 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

56 Human Fetus – 5 weeks

57 ChickenTurtle Rat

58 Review

59 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

60 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

61 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

62 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

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