Understanding Evolution: Key Concepts and Perspectives

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Explore the key concepts of Darwinian evolution, including evidence for evolution, Darwin's theory, and the Modern Synthesis. Reflect on the relationship between spiritual and intellectual perspectives, emphasizing that different ways of thinking can complement each other. Discover the diversity in religious affiliations globally and understand that science and religion can coexist harmoniously. Gain insights into preliminary definitions in biology and the overwhelming evidence supporting the process of evolution over time, including historical and morphological evidence.


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  1. Lecture #1 Darwinian Evolution Image of Darwin 1

  2. Key Concepts: Evidence for evolution Darwin s theory The Modern Synthesis 2

  3. Spiritual vs. Intellectual Different, but not necessarily in conflict The human intellectual experience The human emotional experience The Bible tells us how to go to Heaven, not how the heavens go The Bible tells us how to go to Heaven, not how the heavens go Galileo 3

  4. Reality Check: The world s major religions and the dominant religion in the world s four most populous countries Religious Affiliation United States 82 World China India Indonesia 13 77 33 21 14 13 12 6 ~0 Christian 8 6 14 2 Muslim 2 Non- believers 50 12 2 1 73 Hindu ~0 1 3 32 Other 6 1 4 Buddhist 9 1 1 1 Jewish ~0 ~0 2 ~0 4 SOURCE National Geographic, December 2007

  5. There are many equally valid ways to go to Heaven We rely on our religious texts for moral, emotional and spiritual guidance We rely on science and other intellectual pursuits to gain knowledge about the natural world There need be no conflict in these different There need be no conflict in these different ways of thinking and learning ways of thinking and learning 5

  6. Some preliminary definitions Species individual organisms capable of mating and producing fertile offspring Population a group of individuals of a single species Community a group of individuals of different species Images species, population, community 6

  7. Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 7

  8. Historical Evidence: observed character displacement Changes in beak size recorded over about 2 decades after a natural migration event Photographs by B. Rosemary Grant/Science, 2006 Big-beaked invader Image finches on the Galapagos Resident species shifted to smaller beak size 8

  9. All of agriculture is based on human selection events The domestication of grass ~12,000 years ago Led to the first cultural shift in human civilization Nomadic hunter-gather tribes villages based on agricultural production Other plants and animals as well . Image rice 9

  10. Artificial Selection Brassica oleracea in all its forms Image cabbage, kale, cauliflower, broccoli, Brussels sprouts 10

  11. Farm Animals different breeds Images different breeds of cattle and chickens 11

  12. Cats and Dogs A great dane is the same species as a toy poodle! Images different breeds of cats and dogs 12

  13. The development of pesticide resistance Resistance to insecticides, herbicides, antibiotics .. All natural responses to human generated changes in the environment Diagram development of pesticide resistance due to use of insecticides 13

  14. Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 14

  15. The fossil record extends back BILLIONS of years Images fossils of plants and fish 15

  16. Most form in marine sediments Diagram formation of sedimentary rocks with fossils embedded 16

  17. Fossil substrates can you think of others??? Images other fossil substrates 17

  18. Formation of sedimentary rocks is not uniform in time or space Diagram formation of sedimentary rocks with fossils embedded 18

  19. Critical Thinking The formation of sedimentary rocks is not uniform in time or space Why not??? 19

  20. Critical Thinking The formation of sedimentary rocks is not uniform in time or space Why not??? Dynamic processes! Geological activity Climate Depositional environments 20

  21. Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy 21

  22. The earths crust is very dynamic Diagram dynamic geological processes: tectonic movements, mountain building, erosion 22

  23. Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy 23

  24. Climate is naturally dynamic on a geological time scale Graph of benthic carbonates analogous to climate change over the past 5 million years Benthic carbonates parallel atmospheric temperature changes 24

  25. Critical Thinking How could water temperature affect the formation of sedimentary rocks??? 25

  26. Critical Thinking How could water temperature affect the formation of sedimentary rocks??? Limestone is a sedimentary rock that is formed from the tiny shells of marine organisms The abundance of these organisms is partially dependent on water temperature 26

  27. Formation of sedimentary rocks is highly dynamic Varies with geological activity Tectonic movements, mountain building, erosion Varies with climate Rain, wind, freeze/thaw cycles, water temperature all affect erosion and sedimentation Varies with the depositional environment Finer sediments in still water, coarser sediments with more wave action or other energy WHY??? 27

  28. Play with the ocean In high energy environments (waves) only the heaviest sediments can settle Coastal environments produce sandstones In off-shore environments (no waves) finer sediments can settle Off-shore environments produce siltstones, slates, limestones 28

  29. Sediment size depends on the energy level at the site of deposition Diagram of different depositional environments 29

  30. Formation of sedimentary rocks is highly dynamic THUS sediments tend to be deposited in identifiable layers THUS organisms trapped in sediments form a time sequence The earliest organisms are in the bottom layers and the most recent organisms in the upper layers 30

  31. The Grand Canyon a time sequence Image the Grand Canyon showing layers of sedimentary rock 31

  32. Formation of sedimentary rocks is highly dynamic THUS sediments tend to be deposited in identifiable layers THUS organisms trapped in sediments form a time sequence The earliest organisms are in the bottom layers and the most recent organisms in the upper layers Dating these fossils reveals the history of change 32

  33. Study the geological time scale it s the history of life on earth! The geological time scale Use a search engine to find the geological time scale 33

  34. Of course the fossil record is incomplete! Organisms must be trapped in the right place under the right conditions a rare event Fossils must survive geological processes such as subduction, metamorphosis and erosion Fossils must be found! Have you ever found a fossil??? But what we do have is irrefutable evidence of change over time 34

  35. Fossil Evidence Shows Progression Over Time new species . Diagram evolution of elephant lineages 35

  36. .new traits. Diagram limbs developing from bony fins in tetrapods 36

  37. .transitional forms. Diagram transition from bony fins to limbs 37

  38. Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 38

  39. Comparative morphology homologous structures are derived from a common ancestor Diagram forelimbs of various mammals showing identical bone structure with variation in bone size 39

  40. Fish SalamanderTortoise Chicken Pig Cow Rabbit Human Stage of Development Early Diagram similarities in the embryos of a wide variety of vertebrates Later 40 Strickberger, 1996

  41. Images orchid floral structure 41

  42. Comparative morphology vestigial traits Structures that are physically or functionally reduced but clearly similar to functional structures in related organisms Tiny limb bones in some snakes and aquatic mammals Non-flying wings in ostriches emus, kiwis, penguins Blind eyes in cave-dwelling animals Vestigial tails in humans 42

  43. Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 43

  44. Biogeography Darwin observed patterns of species distribution during his voyage on the Beagle Diagram the voyage of the Beagle 44

  45. Sloths found only in South America, even though similar habitats exist on other continents Image modern and fossil sloths 45

  46. Marsupials almost restricted to Australia though convergent evolution has resulted in many similar eutherian mammals on other continents Diagram of marsupial and eutherian mammals showing similar forms Convergent evolution similar traits in unrelated organisms that evolved under similar selection pressures .more later 46

  47. The Galpagos and other volcanic islands Many closely related endemic species .that are similar to those found on the closest mainland Darwin s conclusion species migrated and evolved new adaptations in their new home Diagram of Darwin s finch lineages 47

  48. Defining Evolution: A process of change over time Cannot deny that this occurs Evidence is overwhelming: Historical within the span of recorded human history Fossils the very long term geological record Comparative morphology and anatomy Biogeography the geographic distribution of species The unity of life 48

  49. Uniformity and Diversity: same DNA, same ATP, same amino acids, same membranes, same aerobic respiration . Image frog in the center of a bromeliad 49

  50. Critical Thinking What is the implication of this uniformity in the basic building blocks of life, even though there are many millions of organisms both extant and extinct??? 50

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