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Evolution

Learn about the different types of evidence supporting evolution, including the fossil record, anatomical comparisons, embryology, and molecular records. Discover how artificial selection and vestigial structures contribute to human-caused evolution. Explore the importance of understanding evolution in various fields, from ecology to agriculture and medicine.

richardstevens
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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. Wallace Darwin

  29. 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

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

  31. Lamarck's Giraffes Acquired characteristics are passed on to the next generation. French Naturalist 1744-1829

  32. 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

  33. SpeciesVariability? Rock Dove

  34. Artificial Selection I liked breeding pigeons!

  35. Darwin’s Observations & Conclusions O1: Organisms produce more offspring than are needed for replacement O2: Population size stays about the same C1: There is competition for survival

  36. Darwin’s Observations & Conclusions O3: Natural resources are limited C2: Most adapted individuals leave more offspring (= natural selection)

  37. Darwin’s Observations & Conclusions O4: Within a population, individuals exhibit variation in their characteristics O5: Some variation is inherited (genetic)

  38. Darwin’s Observations & Conclusions C3: Some organisms exhibit heritable characteristics that make them more likely to survive and produce offspring .

  39. Evolution by Natural Selection Variability in the population Changed environment Isolation of the population Time Genetic Change Result: adaptation leading to a new species

  40. Evolution Variabilityin thepopulation Transport to a differentenvironment Isolation & time Adapted to wind Adapted to calm & shade

  41. Genetic Variation in Giraffe Population Giraffokeryx (extinct- giraffe ancestor 27 mya)

  42. Genetic Variation in Giraffe Population

  43. Giraffes

  44. The HMS Beagle

  45. Darwin’s Voyage 1831-1836

  46. Galapagos

  47. Galapagos

  48. Blue footed boobie Galapagos Tortoises

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