Evolution

1. Evolution http://www.youtube.com/watch?v=faRlFsYmkeY http://www.evolution-of-life.com/en/observe/video/fiche/darwin-on-the-evolution-trail.html

2. Important Vocabulary • Slide # 2 • 1. Species: A group of organisms whose individuals can breed together to produce fertile offspring. • 2. Population: A localized group of individuals belonging to the same species. • 3. Evolution: A slow change in a population over time.

3. Slide # 3 • Charles Darwin explained how Natural Selection could cause a population to adapt and change over time. (note he states- a “population” will change -not an “individual”)

4. Old Theories of Evolution:Lamarck’s Theory of Use and Disuse • Slide # 4 • 1801: Theory of Inheritance of Acquired Characteristics • “Theory of inheritance of acquiredcharacteristics” & “Use and disuse” • If an organism changes in order to adapt to its environment, those changes are passed on to offspring. • Said that changes in organisms occur to help organism reach perfection. • Lamarck

5. Example of Lamarck’s Hypothesis • Slide # 5 • Example of Lamarck’s hypothesis: • Male crab uses small front claw to ward off other males • Because it has been used a lot, front claw becomes larger. • Larger claw trait is passed on to offspring. Even though his hypothesis is flawed, he was the first to address the fact that organisms adapt to their environment

6. The Work of Lyell Influenced Darwin’s Ideas • Slide # 6 • Charles Lyell – English geologist • 1830: On the Principles of Geology • Natural forces & processes that shaped ancient Earth are the same forces acting on Earth today. • Earth’s geologic features formed as a result of gradual processes. • Floods, earthquakes, and glaciers of present do not cause greatdestruction (ex: Grand Canyon) of Earth’s surfaces • Must take millions of years to change geography • 2. Darwin read Lyell’s work while on his voyage & agreed with Lyell’s conclusions • Charles Lyell

7. The Work of Malthus Influenced Darwin’s Ideas • Slide # 7 • 1798: Thomas Malthus -- Englishman • Essay on the Principle of Population • Said that humans tend to have more offspring than nature can support • Food production increases at a slower rate than population • Darwin read Malthus’s essay after he returned from his voyage • Darwin concluded that all organisms produce more offspring than the population can support • Thomas Malthus

8. Charles Darwin: An Unlikely Evolutionist • Slide # 8 • Charles Darwin • 1809: English born naturalist • Went on a 5 year voyage on the HMS Beagle as an unpaid scholar • Collected plants & animals during journey • Darwin did not set out to develop a theory of evolution • Observations and specimens collected helped Darwin formulate his theory of evolution. • Charles Darwin

9. Route of Darwin’s 5 Year Trip • Slide # 9 • Galapagos Islands • Darwin spent a lot of time and collected a lot of specimens from the Galapagos Islands.

10. Darwin’s Observations • Slide # 10 • Galapagos penguin • 14 inches tall • 5 lbs • Eat small fish & sardines • Nests in burrows • In Argentina, Darwin saw earthquakes raising the earth several feet • Shells of marine animals found far inland & at great heights in Andes Mts • Fossils of huge sloths & armadillo-like animals (both extinct) – similar to modern forms • Animals on Galapagos were similar but not same as those on mainland S. America & Antarctica • Chinstrap penguin • 28 inches tall • 9-14 pounds • Eat small fish & krill • Build nests out of small stones

11. Darwin’s Observations on the Galapagos Islands • Slide # 11 • Fewer types of organisms on the islands • Island species differ from mainland species & from island to island • Finches on Galapagos resemble mainland finch, but there were more types on the islands

12. Giant Tortoises of the Galapagos Islands • Slide # 12 • Pinta • Tower • Marchena • Pinta IslandIntermediate shell • James • Fernandina • Santa Cruz • Isabela • Santa Fe • Hood Island • Saddle-backed shell • Floreana • Hood • Each island had a variation of tortoise; long & short neck corresponded to type of vegetation. • Isabela Island • Dome-shaped shell

13. Darwin explained Evolution by Natural Selection • Slide # 13 • 1859: Darwin published On the Origin of Species • Proposed that natural selection was the mechanism for evolution. • Individuals vary in one or more traits & there can be slight differences in their ability to survive & reproduce. • Nature selects those individuals w/ favorable traits to leave more offspring that are better suited (FIT) for their environment. • Descent with modification occurs over time • Each living species has descended, with changes, from other species over time • Published 25 years after Darwin wrote it!

14. Evidence that Supports Evolution: Fossil Record • Slide # 14 • Fossil: preserved remains (bones, teeth, shells) or evidence (imprint or footprint) of ancient organisms. • Fossils found in sedimentary rock • Younger sediments deposited on top of older sediments • Older sediments contain older, simpler fossils • Younger sediments contain younger, more complex fossils • Fossils found in sediments of organisms that are extinct. • Trilobites are extinct!

15. Evidence that Supports Evolution: Geographic Distribution of Living Species • Slide # 15 • Similar animals on each continent live in similar ecological conditions • They were exposed to similar pressures of natural selection. • Because of similar selection pressures, different animals ended up evolving similar characteristics • Beaver • Beaver • Muskrat • Beaver andMuskrat • Coypu • Capybara • Coypu andCapybara • NORTH AMERICA • Muskrat SOUTH AMERICA • Capybara • Coypu

16. Evidence that Supports Evolution: Homologous Structures • Slide # 16 • Homologous structures: similar structures but different functions • Structures develop from same clump of embryonic cells • Provides evidence that four-limbed vertebrates descended from a common ancestor. • Vestigial structures: structures or organs that are reduced in size; do not seem to serve a useful function • Homologous & vestigial structures imply that common genes are involved. • Homologous structures: forelimbs of vertebrates • Pelvis & femur bones are vestigial in whales

17. F. Analogous Structures • Structures that are similar in function, but not in structure. • Examples—wings of a bird and wings of a butterfly. • The Theory: • Not considered evidence—does not fit in with the Theory.

18. Evidence that Supports Evolution: Similarities in Embryology • Slide # 17 • The embryos of vertebrates are very similar during early development. • The same groups of embryonic cells develop in the same order and in similar patterns to produce tissues & organs. • Common cells & tissues growing in similar ways produce homologous structures. • Implies that common genes are involved. • Embryos of vertebrates develop gill slits and tails.

19. The Theory of Evolution

20. How did life begin?A question still not answered. • A Theory: • 4.5 billion years ago the Earth was a ball of molten rock, then cooled, forming a rocky crust, water vapor condensed to form oceans, chemical reactions produced simple organic molecules, then formed more complex molecules which in turn formed the first living cell. • TIME + CHANCE = LIFE

21. Formation of Life • A Theory: • It has been hypothesized that the Earth’s early atmosphere lacked free oxygen, but was made of nitrogen gas, hydrogen gas, water vapor, ammonia, and methane. • Note: oxygen is required to form the ozone layer which protects the Earth from the harmful UV rays of the sun—without it, life could not exist. • TIME + CHANCE = LIFE

22. Formation of Life • A Theory: • Miller-Urey experiment- simulated the early Earth’s conditions and used electrical sparks, produced organic compounds, including amino acids. (None of which were the 20 amino acids found in living organisms.) • Note: amino acids will not form in the presence of oxygen Note: Miller was the “intelligent designer”—the theory of evolution does not allow for “intelligent design”. Note: Louis Pasteur already disproved “spontaneous generation”—where life comes from nonliving things—in 1864.

23. A thought—a cell is made of a billion nonliving parts. —you have to have proteins to be able to make proteins, you have to have DNA for the instructions to make the proteins— …so “which came 1st –the chicken or the egg?” The probability of an average protein (which has approximately 300 amino acids) would be 1:10191—a cell is made of lots of proteins—so for an entire cell to be put together would be a probability of 1:1040000 for 1 cell. • TIME + CHANCE = LIFE

24. TIME + CHANCE = LIFE

25. Evidence of Evolution

26. A. Fossils • The fossil record indicates that billions more species than those that exist today lived in the past and have become extinct because of mass extinctions—due to worldwide weather and geologic changes (like a Flood).

27. B. Dating Fossils • Earth has been dated at 4.5 billion years old. • Dating Methods: • Radiometric Dating • Relative Dating

28. 1. Radiometric Dating • This method of dating relies on the decay of radioactive elements (isotopes), such as uranium, potassium, rubidium and carbon. • The rate of decay is called a “half- life”. Radioactive isotopes are atoms with unstable nuclei, which break down over time at a supposed “known” steady rate.

29. 1. Radiometric Dating • Radioactive elements decay gradually into other elements. The original element is called the parent, and the result of the decay process is called the daughter element.

30. 1. Radiometric Dating • 50 grams • 50 grams • 75 grams • 25 grams • 87.5 grams • 12.5 grams • 6.25 grams • 93.75 grams • 3.125 grams • 96.875 grams

31. Radiometric Dating: radioactive elements • Uranium • Lead • r • Potassium • Argon • Rubidium • Serium • Carbon • Nitrogen • Note: Carbon dating can only be used on once living organisms.

32. Carbon Dating • The “half-life” rate of decay for C-14 to convert to N-14 is 5,730 years. • So, in two half-lives, or 11,460 years, only one-quarter will be left. If the amount of C-14 relative to C-12 in a sample is one-quarter of that in living organisms at present, then it has a theoretical age of 11,460 years.

33. Carbon Dating

34. Carbon Dating • Anything over 50,000 years old, should have no detectable C-14 left. That is why carbon dating cannot date fossils with millions of years. • If a sample contains C-14, it is good evidence that it is not millions of years old.

35. Problems with Radiometric Dating • Assumptions: • The starting conditions are known (for example, that there was no daughter isotope present at the start, or that we know how much was there). • Decay rates have always been constant. • Systems were closed or isolated so that no parent or daughter isotopes were lost or added—(did the atmosphere have any effect on the sample?)

36. Problems with Radiometric Dating • With Carbon Dating: • Has the ratio of C-12/C-14 always been the same? • What could affect this ratio? • Industrial revolution, nuclear explosion, decay of the Earth’s ozone—we may have had far less C-14 in the atmosphere 1400 years ago than the present amount make the consumption of C-14 less.

37. Discrepancies with Radiometric Dating

38. 2. Relative Dating: comparison of rock layers • Assumptions: • 1. Fossils are formed in vertical layers of sedimentary rocks. • 2. The oldest fossils are in the lower levels and the youngest are in the upper levels. • 3. The actual age may not be know, but a comparison can be made between the layers.

39. *fossils found in lower strata were typically deposited first and are assumed to be older (this method is also known as superposition). • However, this method doesn't always work, either because the layers weren't deposited horizontally to begin with, or because they have been overturned. “Catch 22”

40. More Evidence

41. C. Endosymbiotic Theory • The mitochondria and chloroplasts are the same size as prokaryotic cells • They contain DNA in a ring and ribosomes. • They reproduce by simple fission. • They have inner membranes. • The Theory: • Proposes that mitochondria and chloroplasts are the descendants of bacteria from the Kingdom Eubacteria.

42. C. Endosymbiotic Theory

43. D. Vertebrate Embryos • The presence of gills and tails in the early stages of all vertebrate embryos. • The Theory: • Appears as though that aquatic, gill-breathing vertebrates preceded air-breathing, terrestrial species.

44. D. Vertebrate Embryos

45. E. Homologous Structures • Modified structures seen among different groups. • Example—the forelimbs of reptiles, birds, and mammals • The Theory: • Appear as though they evolved from a common ancestor. Same structure—different function

46. G. Vestigial Structures • They are body structures that are reduced in function in a living organism. • Examples: penguin wings, snake pelvic girdle, human appendix. • The Theory: • May have been used by ancient ancestors.

47. H. Similar DNA • Organisms with similar characteristics have similarities in their DNA or RNA. • The Theory: • Possibly came from a common ancestor.

48. J. Speciation—the process by which a new species is formed. • Possible Causes: • Reproductive isolation-- Occurs when individuals of a population are unable to interbreed and produce fertile offspring. • Geographic isolation– when two populations can no longer interbreed because of a geographical barrier (mountain, ocean, etc.)

49. Behavioral isolation—when courtship rituals change. • Gametic isolation—when gametes do not fuse or a zygote does not form properly. • Physical mechanisms—when reproductive structures do not fit for mating (plant or animal)

50. Summary • All living things are similar.