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anjolie-beard

Evolution - PowerPoint PPT Presentation

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Evolution
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  1. Evolution

  2. Evidence supporting evolution Fossil record shows change over time Anatomical record comparing body structures homology & vestigial structures embryology & development Molecular record comparing protein & DNA sequences Artificial selection human caused evolution

  3. Fossils help decipher life’s history Layers of rock contain fossils new layers cover older ones creates a record over time fossils show evidence for past life over a long period of time Hyracotherium Laetoli

  4. Fossils tell a story… the Earth is old Life is old Life on Earth has changed

  5. Evolution of birds Today’s organisms descended from ancestral species Fossil of Archaeopteryx lived about 150 mya links reptiles & birds

  6. ? ? ? Complete seriesof transitionalfossils ? Whale evolution Land Mammal Where are theintermediate fossils? Ocean Mammal

  7. Vestigial organs Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Hind limb buds Dolphin embryo

  8. Evolution from sea to land • 2006 fossil discovery of early tetrapod • 4 limbs • Missing link from sea to land animals ichthyostega

  9. Anatomical record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

  10. Comparethe bones Homologous Structures

  11. But don’t be fooled by these… • Analogous structures • look similar on the outside • Same function • different structure & development on the inside • different origin • no evolutionary relationship Solving a similar problem with a similar solution

  12. Analogous structures • Dolphins: aquatic mammal • Fish: aquatic vertebrate • both adapted to life in the sea • not closely related

  13. Convergent evolution 3 groups with wings Does this mean they have a recent common ancestor? Flight evolved 3 separate times— evolving similar solutions to similar “problems”

  14. Convergent evolution led to mimicry • Why do these pairs look so similar? Monarch male poisonous Viceroy male edible

  15. Comparative embryology Development of embryo tells an evolutionary story similar structures during development

  16. Dog Human Macaque Bird Frog Lamprey 8 32 45 125 67 0 10 20 30 40 50 60 70 80 90 100 110 120 Molecular record Comparing DNA & protein structure everyone uses the same genetic code! DNA • compare common genes • compare common proteins number of amino acids different from human hemoglobin

  17. Building “family” trees Closely related species are branches on the tree — coming from a common ancestor

  18. Evolution: the source of Earth’s biodiversity Biological evolution: genetic change in populations of organisms across generations Natural selection: reproductive fitness

  19. Understanding evolution is vital • to understand how organisms adapt to their environment and change over time. • It is needed for ecology, a central component of environmental science. • Relevant for agricultural, medicine, pesticide resistance, environmental health

  20. Genetic variation Genes ofbetter-adapted individuals will be more prevalent than those of less well-adapted individuals in future generations. Adaptive trait (adaptation): a trait (characteristic) that promotes reproductive success Mutations: accidental changes in DNA that may be passed on to the next generation Non-lethal mutations provide the genetic variation on which natural selection acts. Sexual reproduction, which involves recombination (the mixing of parental genes), also leads to variation.

  21. Evidence of natural selection is everywhere • functioning: beaks in honeycreepers

  22. Artificial selection • How do we know natural selection can change a population? • we can recreate a similar process • “evolution by human selection” “descendants” of wild mustard

  23. Artificial selection Humans create the change over time “descendants” of the wolf

  24. Artificial selection

  25. Artificial Selection gone bad! Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance

  26. Insecticide resistance Spray the field, but… • insecticide didn’t kill all individuals - variation • resistant survivors reproduce • resistance is inherited • insecticide becomes less & less effective

  27. Evolution generates biodiversity Biological diversity (biodiversity): an area’s sum total of all organisms The diversity of species Their genes Their populations Their communities

  28. Evolution: A Preview Adaptation of a population to a new environment – may lead to a new species Darwin’s Observations More offspring than needed Population size is about the same Individuals differ Some variation is inherited

  29. Evolution: A Preview Adaptation of a population to a new environment – may lead to a new species You won’t see this unless you are prepared to see it Darwin’s Observations More offspring than needed Population size is about the same Individuals differ Some variation is inherited

  30. Expeditions Access to remote places to make biodiversity collections Alfred Wallace Brazil Malay Peninsula 8 years 125,000 animal specimens

  31. Age of the Earth Uniformitarians Present mechanisms hold for the past Erosion & uplifting = mountains Catastrophists A few violent events occur suddenly

  32. Age of the Earth Uniformitarians Earth must be old Catastrophists Earth can be young (Bishop Usher: “October 22, 4004 BC” ) Not an evolutionary question

  33. Malthus & Population Tendency to rise beyond numbers that can be supported by the environment Reduced by disease, war 1776-1834 populationsize time

  34. Evolutionary Questions Do species change? If so, how? Evolution: Change through time

  35. Jean-Baptist Lamarck Outstanding Naturalist Observations Variability within species Trend of increasing complexity in species

  36. Lamarck’s Theory of Evolution Theory of Acquired Characteristics Species change in response to a changed environment Species can change by “use” Changes are passed on Published in 1809

  37. Lamarck’s Giraffe and stretching until neck becomes progressively longer Keeps stretching neck to reach leaves higher up on tree and stretching Original short necked ancestor

  38. Darwin’s Giraffe Natural selection favors longer necks: better chance to get higher leaves. Favored character passed on to next generation Original group exhibits variation in neck length After many, many generations the group is still variable, but shows a general increase in neck length

  39. Lamarck’s Contributions to the Development of Evolutionary Theory • Presented evidence that fossils were the remains of extinct animals. • Occurrence of fossils suggested to Lamarck that profound changes had taken place during the history of life on earth. • Proposed the hypothesis of evolution by the inheritance of acquired characteristics.

  40. Lamarck’s Theory of Evolution Lamarck had good data It is good common sense But it isn’t right

  41. Theories in Lamarck’s time If data support your theory, and You can’t think of an alternative theory Your theory must be right

  42. Theories Today Poor theories are not discarded A poor theory can only be replaced by a better one A subtle but important difference

  43. Darwin (1809-1882) Ground work for the acceptance of evolution already done Many of the main ideas already known But …Darwin relied on his own observations

  44. Darwin: Accomplishment Age 27: 5 year voyage completed Age 30: good travel book written Middle age: natural history expert Age 50: “Origins” published Lifetime = 20 books, 80 papers

  45. Darwin: Attributes Gifted experimentalist Equivalent of a “millionaire” Quiet & modest lifestyle

  46. Darwin: Attributes Tremendous energy Gift of simplicity Courageous Wrote so that the common person could read his works

  47. Darwin: Chronology College, but “sporting set” Active naturalist, collector Beagle as companion to Fitzroy Gone for 5 years

  48. Darwin South America = no rabbits But animals therewere similar to rabbits “Why no rabbits?” Ancestors had to get there or they must have originated there

  49. European Rabbit: Oryctolagus cuniculus