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The Evidence for Evolution

The Evidence for Evolution. Evidence #1. Fossil Record. Evidence of Evolution #1 – Fossil Record. Fossils are the preserved remains of once-living organisms Rock fossils are created when three events occur organism buried in sediment calcium in bone or other hard tissue mineralizes

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The Evidence for Evolution

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  1. The Evidence for Evolution

  2. Evidence #1 Fossil Record

  3. Evidence of Evolution #1 – Fossil Record • Fossils are the preserved remains of once-living organisms • Rock fossils are created when three events occur • organism buried in sediment • calcium in bone or other hard tissue mineralizes • surrounding sediment hardens to form rock

  4. Fossil Evidence of Evolution

  5. Fossil Evidence of Evolution Fossil records document the course of life through time

  6. Fossil Evidence of Evolution • Fossils document evolutionary transition • The oldest known bird fossil is the Archaeopteryx • It is intermediate between bird and dinosaur • Possesses some ancestral traits and some traits of present day birds • Archaeopteryx was first found in 1859

  7. Fossil Evidence of Evolution Fossil of Archaeopteryx

  8. Fossil Evidence of Evolution Recent discoveries • Four-legged aquatic mammal • Important link in the evolution of whales and dolphins from land-dwelling, hoofed ancestors • Fossil snake with legs • Tiktaalik: a species that bridged the gap between fish and the first amphibian • Oysters: small curved shells to large flat shells

  9. Fossil Evidence of Evolution Whale “missing links”

  10. Fossil Evidence of Evolution Evolutionary change in body size and toe reduction of horses

  11. Fossil Record Activity • Gradualism – slow gradual change in a population over time • Uniformitarianism; constant, small changes in the environment result in slow changes in the population • Punctuated Equilibrium – fast change in a population in a short period of time (punctuated) followed by little/no change over a long period of time (equilibrium) • Mass extinctions are a cause of the quick change in a population

  12. Adaptive Radiation • A single species has evolved, through natural selection and other processes, into diverse forms that live in different ways • An example is the different varieties of finches that were found on the different islands that Darwin visited. Each variety was perfectly fit for the different islands’ environments. • However, they all descended from a common ancestor

  13. Activities • Fossil Record Activity • Analysis of phylogenetic trees and adaptive radiation

  14. Evidence #2 Morphology

  15. DivergentEvolution • when one species becomes many different species to fill available niches • Adaptive Radiation: periods of evolution in which organisms form new species due to adaptations that allow them to fill different niches in the community. i.e. Darwin’s Finches on the Galapagos Islands • Homologous Structures

  16. Evidence for Evolution #2 – Morphology • Homologous Structures -Similarity in structure due to common decent (had a common ancestor), regardless of the different environments in which they now live; same structure, different function i.e.- human hands, whale fins, bat wings

  17. Evidence for Evolution #2 – Morphology

  18. Evidence for Evolution #2 – Morphology

  19. Convergent Evolution • the appearance of apparently similar structures/ features in organisms of different lines of descent. • Analogous structures • Birds & Bats • Dolphins & Sharks • Penguins & Seals

  20. Evidence for Evolution #2 - Morphology • Analogous Structures - Similar structures based on naturally selected adaptations for the same function in different organisms but that did NOT result from a common ancestor • i.e – wings in birds, bats, insects

  21. Analogous Examples

  22. Convergent Evolution Convergence among fast-swimming predators

  23. Mimicry • A phenomenon in which an individual gains an advantage by looking like the individuals of a different species. • “A mimic is any species that has evolved to appear similar to another successful species in order to dupe predators into avoiding the mimic, or dupe prey into approaching the mimic.”

  24. Monarch Viceroy

  25. Yellow Jacket Sand Wasp

  26. Dronefly Honey Bee

  27. Sryphid Fly Paper Wasp

  28. Coral Snake Colubrid Snake

  29. Mantid Orchid

  30. Catkin (plant) Caterpillar

  31. Evidence for Evolution #2 - Morphology • Vestigial Structures - Remnants of once useful structures (in ancestral species) but that no longer serve a purpose in this specific species (although could still be useful in similar species) i.e. – human appendix, hind limbs of snakes and whales

  32. Vestigial Examples

  33. Vestigial structures of a whale

  34. Blind Salamander

  35. Blind Cave Fish

  36. Feel your gums above your canine teeth • vestigial roots

  37. Activity • Homologous structures coloring assignment and questions

  38. Evidence #3 Embryology

  39. Dolphin Embryo

  40. Human Embryo • Figure 2.4.1. Cat and human embryos in the tailbud stage. A cat embryo is shown on top, a human embryo below. Note the post-anal tail in both, positioned at the lower left below the head of each. The human embryo is about 32 days old. Cat Embryo

  41. OOPS!

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