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Chapter 15 Evolution. Think About It? What is evolution? What is evolution? Why does it happen? Why does it happen? How does it happen? How does it happen?

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Presentation on theme: "Chapter 15 Evolution. Think About It? What is evolution? What is evolution? Why does it happen? Why does it happen? How does it happen? How does it happen?"— Presentation transcript:

1 Chapter 15 Evolution

2 Think About It? What is evolution? What is evolution? Why does it happen? Why does it happen? How does it happen? How does it happen?

3 What is evolution? Change in a population over time Change in a population over time at genetic level at genetic level mutations mutations

4 Mutations Change in DNA code Change in DNA code can affect phenotype can affect phenotype

5 REVIEW: From Gene to Protein

6 The Darwin Dude 5 year voyage on Beagle (1831-36) 5 year voyage on Beagle (1831-36) Naturalist: surveyed coast of S.A. Naturalist: surveyed coast of S.A. Wrote Origin of Species Wrote Origin of Species

7 Collected: Collected: –Rocks –Fossils –Plants –Animals Charles Lyells Principles of Geology proposed Earth was millions of years old! Charles Lyells Principles of Geology proposed Earth was millions of years old! The Darwin Dude

8 Explained marine life at high elevation in the Andes Explained marine life at high elevation in the Andes Giant fossil versions of smaller living mammals Giant fossil versions of smaller living mammals Earthquakes could lift rocks great distances very quickly. Earthquakes could lift rocks great distances very quickly. Lyell:

9 Galapagos Island Facts Part of Ecuador Part of Ecuador 13 main volcanic islands 13 main volcanic islands Formed between 5 - 10 MYA Formed between 5 - 10 MYA

10 Darwin & Galapagos Organisms adapted to their environment Organisms adapted to their environment Darwins Finches Darwins Finches – Gould (ornithologist) finches were separate species not found any where else. Mechanism for evolution = Natural Selection Mechanism for evolution = Natural Selection

11 Darwin believed new species appear gradually through small changes in ancestral species. Darwin believed new species appear gradually through small changes in ancestral species. Breeders – can promote specific traits by selecting and breeding organisms that have the most exaggerated expressions of those traits. Breeders – can promote specific traits by selecting and breeding organisms that have the most exaggerated expressions of those traits. Known as Artificial Selection! Artificial Selection:

12 If humans could change species by artificial selection, the same process could work in nature! If humans could change species by artificial selection, the same process could work in nature! Given enough time this process could produce new species ! Given enough time this process could produce new species ! Inference:

13 Artificial Selection:

14 Noteworthy Species

15 Darwins Finches Adaptive Morphology

16 Why do species change? Variations & adaptations help organisms survive Variations & adaptations help organisms survive

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18 Camouflage

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20 Human population, if unchecked, would eventually outgrow its food supply, leading to a competitive struggle for existence. Human population, if unchecked, would eventually outgrow its food supply, leading to a competitive struggle for existence. Darwin believed Malthuss ideas could be applied to the natural world. Darwin believed Malthuss ideas could be applied to the natural world. –Some competitors are better equipped for survival than others! Thomas Malthus:

21 Natural Selection Organisms with favorable traits survive & reproduce Organisms with favorable traits survive & reproduce Variation is key Variation is key

22 Natural Selection (cont.) Struggle for existence Struggle for existence Species become better fit for their environment Species become better fit for their environment If not they could DIE! If not they could DIE!

23 Natural Selection (cont.) 4 Main Principles (pg 421): 1. Variation 2. Heritability 3. Overproduction 4. Reproductive Advantage

24 Individuals in a population differ from one another. Individuals in a population differ from one another.Example: 1. Variation:

25 2. Heritability: Variations are inherited from parents. Variations are inherited from parents.Example: X

26 3. Overproduction: Populations produce more offspring than can survive. Populations produce more offspring than can survive.Example: – 48 white tiger litters produces 148 cubs –105 of them died without reproducing71%

27 4. Reproductive Advantage: Some variations allow the organism that possesses them to have more offspring than the organism that does not possess them. Some variations allow the organism that possesses them to have more offspring than the organism that does not possess them.Example: White tigers have powerful jaws & teeth, very strong sense of smell, sharp eyesight, and excellent swimmers!

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29 Types of Natural Selection 1. Stabilizing Selection: Average phenotype favored Ex. Human baby weight

30 Stabilizing Selection

31 Types of Natural Selection 2. Directional Selection: increases extreme versions of traits Ex. Peppered Moth, Darwins finches

32 Peppered Moth: Natural Selection

33 Directional Selection

34 Types of Natural Selection 3. Disruptive Selection: splits populations into 2 groups Both extremes favored Both extremes favored Ex. Marine & Land Iguanas Ex. Marine & Land Iguanas

35 Disruptive Selection

36 V = Variation: All life forms vary genetically within a population. It is this genetic variation upon which selection works. I = Inheritance: Genetic traits are inherited from parents and are passed on to offspring. S = Selection: Organisms with traits that are favorable to their survival get to live and pass on their genes to the next generation. T = Time: Evolution takes time. Evolution can happen in a few generations, but major change, such as speciation, often takes long periods of time.

37 Evidence of Evolution 1. Fossil Record Fossils: preserved evidence Fossils: preserved evidence Found in Sedimentary rock Found in Sedimentary rock

38 Provides record of species that lived long ago. Provides record of species that lived long ago. Some similar to current ones! Some similar to current ones! Some species unchanged! Some species unchanged! Evidence of Evolution

39 Similar fossil forms: Glyptodon & Glyptodon &Armadillos

40 Species unchanged: Horseshoe Crab! Horseshoe Crab!

41 Fossil Record (cont) A. Soft parts dont fossilize B. Specific conditions are needed to form fossils C. Hundreds of transitional fossils found

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43 Classes of Traits: Two major classes of traits while studying transitional fossils: Two major classes of traits while studying transitional fossils: –Derived traits: newly evolved features –Ancestral traits: more primitive features that appear in ancestor forms.

44 2. Homologous Structures: Anatomically similar structures Anatomically similar structures Evidence of common evolutionary origin Evidence of common evolutionary origin Evidence of Evolution

45 Homologous Structures

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49 Analogous Structures: Can be used for same purpose and can be superficially similar in construction but are not inherited from a common ancestor. Can be used for same purpose and can be superficially similar in construction but are not inherited from a common ancestor.

50 Analogous Structures:

51 3.Embryology: similarities in embryos similarities in embryos Evidence of Evolution

52 Embryology: Embryo – early, pre-birth stage of an organisms development. Embryo – early, pre-birth stage of an organisms development. Vertebrate embryos exhibit homologous structures during certain phases of development. Vertebrate embryos exhibit homologous structures during certain phases of development.

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54 4.Compararative Biochemistry: Organisms have similar DNA, genes and enzymes Evidence of Evolution

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56 Comparative Biochemistry: The more closely related the species are, the greater number of amino acid sequences they will share. The more closely related the species are, the greater number of amino acid sequences they will share. –Ex. Chimpanzees and Humans share 96% similar sequences!

57 Humans & Chimpanzees: Human genome is 96% similar to great ape species. Human genome is 96% similar to great ape species. Pan troglodytes (species of chimp) used in study Pan troglodytes (species of chimp) used in study –The number of genetic differences between humans and chimps is ten times smaller than that between mice and rats.

58 Pan troglodytes (common Chimp)

59 5. Vestigial Structures: reduced in size, no longer have function reduced in size, no longer have function Evidence of Evolution

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61 Formation of new species Formation of new species Become genetically different Become genetically different What is Speciation?

62 What are Species? Group of organisms that can interbreed & produce fertile offspring Group of organisms that can interbreed & produce fertile offspring

63 Infertile Species Horse + Donkey = Mule 64 ch. + 62 ch. = sterile

64 Liger http://www.youtube.com/watch?v=WdTl n4QwexQ&feature=related

65 Species Loop Hole Not a perfect definition Not a perfect definition Used for classification Used for classification Some different species can produce fertile offspring Some different species can produce fertile offspring

66 Grizzly Bear & Polar Bear Pizzly or Grolar Pizzly or Grolar

67 Rate of Speciation Gradualism: Evolution occurring at slow rate Gradualism: Evolution occurring at slow rate Punctuated Equilibrium: Evolution occurring at irregular rates Punctuated Equilibrium: Evolution occurring at irregular rates

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69 Cause of Speciation 1. Geographic Barriers Mountains, Rivers, etc. Mountains, Rivers, etc. 2. Environment Changes

70 3. Reproductive Isolation Examples: Examples: –mating at different times –birds mating with others who sing a particular song. Cause of Speciation

71 1. Adaptive radiation (divergent evolution) 2. Coevolution 3. Convergent evolution Patterns of Evolution:

72 Relatively short period of time Relatively short period of time 1 species gives rise to many 1 species gives rise to many Usually occurs after mass extinctions Usually occurs after mass extinctions 1. Adaptive Radiation:

73 Evolution of 1 species affects the evolution of another species. Evolution of 1 species affects the evolution of another species. 2. Coevolution:

74 Unrelated species evolve similar traits Unrelated species evolve similar traits Under same environmental Under same environmental pressures pressures 3. Convergent Evolution:


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