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Evolution Chapter 13 “A change over time” FT3FU2XOgo FT3FU2XOgo

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Presentation on theme: "Evolution Chapter 13 “A change over time” FT3FU2XOgo FT3FU2XOgo"— Presentation transcript:

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2 Evolution Chapter 13 “A change over time”

3 FT3FU2XOgo FT3FU2XOgo s=expand s=expand

4 The Theory of Evolution Evolution literally means to change over time. A theory is a well supported, testable explanation that observes observations from the natural world

5 Questions that evolution attempts to answer. How do species adapt to changes in the environment? How do new species develop?

6 Charles Darwin Studied to be a doctor and a minister 1831 sailed around the world as a naturalist on the HMS Beagle

7 HMS Beagle

8 Darwin ’ s Voyage

9 Galapagos Islands

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13 15-2 Darwin ’ s Influences

14 James Hutton Geologist Proposed that the earth was millions of years old based on geologic evidence

15 Sir Charles Lyell Geologist Proposed that geologic changes occur slowly over long periods of time. Darwin read his book, Principles of Geology, on the Beagle

16 Jean Baptiste Lamarck French Naturalist Published his ideas on evolution in 1809 in Philosophie zoologique

17 Lamarck ’ s Hypothesis Organisms Strive for Perfection – all individuals are trying to better themselves

18 Lamarck ’ s Hypothesis Use and Disuse – If an individual uses a trait it will be more useful If an individual does not use a trait it will decrease in usefulness

19 Lamarck ’ s Hypothesis Inheritance of Acquired characteristics

20 Analyzing Lamarck ’ s Hypothesis There is no evidence to suggest that plants and animals are trying to improve themselves

21 Analyzing Lamarck ’ s Hypothesis Use and disuse do not change all characteristics Stretching will not make you taller Reading will not make your eyesight better

22 Analyzing Lamarck ’ s Hypothesis Acquired characteristics are not inherited A mouse that loses its tail will still produce offspring with tails

23 Erasmus Darwin Charles Darwin’s Grandfather Physician and Scientist 'All vegetables and animals now living were originally derived from the smallest microscopic ones.'

24 Thomas Malthus – Economist Human Population would be limited Starvation War (Competition) Disease

25 15-3 Darwin Presents His Case

26 Alfred Wallace Developed his own theory of Natural Selection Contacted Darwin This caused Darwin to finally publish his theory with Wallace

27 On Origins of Species After publishing with Wallace, Darwin submitted all of his ideas in a book titled On Origin of Species, By Means of Natural Selection in 1858

28 Artificial Selection Darwin was influenced to believe change was possible because of the humans selecting for traits in plants and animals.

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30 Darwin ’ s Theory Evolution “Change” is driven by natural selection

31 Summary of Darwin ’ s Theory

32 Variation There are differences within a population Mutation and Sexual Reproduction

33 Competition for resources Not all offspring will survive Starvation Overcrowding Predation

34 Fitness Some of the variants will have an advantage over the others, they will survive and produce more offspring

35 Reproduction and Inheritance These advantages will be passed on to the next generations

36 Descent with Modification Species alive today are descended with modification from ancestral species

37 Tree of Life All species are connected on a single tree of life

38 Modern Theory Mendel’s discoveries in genetics explained a great deal in evolution

39 Evidence for Evolution Fossil Record Anatomy Development Molecular Evidence

40 Fossil Record Since most of the “ancestor” species are extinct, fossils are the only evidence that can be examined. Intermediate “missing link” fossils are very informative

41 Archaeopterix A fossil of a bird like creature Has feathers, teeth and claws in its wings

42 Whale Ancestors gKKs gKKs

43 Anatomy Structures similarities in body structure indicates organisms are related

44 Homologous Structures Structures that have common function and design (ancestry)

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46 Vestigial Organs Structures that have reduced size and or function JE

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51 Developmental Evidence Similarities in embryonic development are interpreted to mean closer relationships.

52 Developmental Evidence Similarities in embryonic development are interpreted to mean closer relationships.

53 Molecular Evidence Organisms are considered to be more closely related if DNA sequences in genes are more similar Amino acid sequences in proteins is more similar

54 Molecular Evidence Organisms are considered to be more closely related if DNA sequences in genes are more similar Amino acid sequences in proteins is more similar

55 Strengths of Darwin ’ s Theory Many discoveries in Physics, Geology and Biology have supported and expanded Darwin’s ideas

56 Strengths of Darwin ’ s Theory Many discoveries in Physics, Geology and Biology have supported and expanded Darwin’s ideas

57 Weaknesses of Darwin ’ s Theory Researchers still debate how new species arise and how they become extinct. The origin of life is still very uncertain

58 Evolution of Populations Chapter 14

59 Genes and Variation Variation – differences between individuals of a species Produced by two processes Mutation – random changes in DNA Sexual Reproduction- combining genes from two gametes

60 Single Gene Traits Several traits are controlled by a single gene and are either dominant or recessive.

61 Polygenic Traits Poly-genic means “many genes” Most traits are controlled by several genes and can show up in many different forms.

62 Normal Curve Most individuals are intermediate, extremes are less common

63 Microevolution Micro – small Microevolution is change within a species Gene Pool – all of the genes in a population Allele Frequency – how many times a certain allele shows up in the population

64 Microevolution Any change in Allele frequency in a population is considered microevolution

65 English Peppered Moth The English Peppered Moth The moth was usually white with dark spots During the Industrial Revolution (1850’s) soot covered many of the white barked trees More and more dark colored moths appeared at the same time Kettlewell’s experiments suggested this was due to natural selection

66 English Peppered Moth The English Peppered Moth The moth was usually white with dark spots During the Industrial Revolution (1850’s) soot covered many of the white barked trees More and more dark colored moths appeared at the same time Kettlewell’s experiments suggested this was due to natural selection

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68 Microevolution in Humans Sickle Cell Anemia is a recessive (hh) disease found mainly in Africa A carrier (Hh) for the disease has resistance to malaria

69 Delta 32 Mutation Delta 32 mutation occurs in 10-15% of whites of European descent This mutation gave resistance to the plague Most of the people without this allele died of the plague causing the allele frequency to rise The mutation also gives resistance to HIV infection

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76 Selection Selection can be one of 3 forms Directional Stabilizing Disruptive

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78 Stabilizing Selection Both Extremes are selected against The population is stabilized

79 Directional Selection One of the extremes is selected against, the population shifts away

80 Disruptive Selection The most common variation is selected against spitting the species two groups

81 Genetic Drift In small population individuals may pass on more genes by chance. This is called genetic drift. Large populations are not affected by genetic drift

82 Genetic Drift Population 18 9 Heads 9 Tails

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84 Population 18 6 Heads 12 Tails

85 Can a species stop evolving? Hardy Weinberg equilibruim in order for evolution of a species not to occur (all allele frequencies stay the same) 5 evolutionary forces must not act

86 Hardy Weinberg Equilibrium Populations do not evolve if there is Random Mating no movement into or out of the population no genetic drift, large population no natural selection no mutation

87 16-3 The Process of Speciation Speciation –the production of a new species Species – a group of individuals that reproduce in nature and produce fertile offspring Isolation – the factor that prevents the new species from reproducing with the ancestral species

88 Behavioral Isolation Mating songs or rituals are different, so the two species don’t interbreed

89 Behavioral Isolation Groups are not attracted to each other for mating

90 Geographic Isolation Groups are physically separated and no longer interbreed

91 Temporal Isolation Groups reproduce at different times of day or year

92 Mechanical Isolation Structural differences prevent mating between individuals of different groups

93 Ecological Isolation Groups are adapted to different habitats, hybrids aren’t adapted well to either

94 Reproductive Failure Mating between groups fail to produce fertile offspring

95 Speciation Continued Once populations are isolated, different pressures select different traits When the populations will no longer interbreed, new species have been formed

96 Natural Selection - 2 forms Ecological Selection – better suited to survive in the environment Sexual Selection – Males compete for access to females Females select males with “good gene” markers

97 Sexual Dimorphism Dimorphismdi-morph-ism Two forms Males are usually larger Males would have ornaments (antlers, manes, colors)

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99 Patterns of Evolution

100 Macro Evolution Macro – Large Idea that species can split to form new species All life forms are related through a common ancestor

101 Divergent Evolution Similar species develop different adaptations to different environments

102 Convergent Evolution Two species develop similar adaptations to the same environment.

103 Coevolution Two or more species adapting to each other

104 Rate of Evolution Slow and Steady or in Spurts? Gradualism – the idea that small changes build up slowly over time to produce large changes. Expectations – many intermediate “missing link” fossils

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106 Punctuated Equilibrium The idea that populations go through periods of stability followed by short periods of rapid change. Expectations – fewer intermediate fossils

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108 Endosymbiont Theory Endo –inside Symbiont – symbiotic “mutualistic” relationship

109 Endosymbiont Theory This theory suggests that mitochondria and chloroplasts were once independent living organisms These organisms were “eaten” by larger cells, but remained alive

110 Endosymbiont Theory Evidence for endosymbiosis Each mitochondrian has its own circular chromosome of DNA Very similar to a bacteria Reproduce on its own Ribosomes are very similar to bacterial ribosomes


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