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Theories and Patterns of Evolution

Theories and Patterns of Evolution. Chapter 15. Theories of Evolution. Biological Evolution: the change of populations of organisms over time New life forms are really modified versions of older ones in same geographic area 2 Explanations: Lamarck’s Darwin’s. Jean Baptiste Lamarck.

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Theories and Patterns of Evolution

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  1. Theories and Patterns of Evolution Chapter 15

  2. Theories of Evolution Biological Evolution: the change of populations of organisms over time • New life forms are really modified versions of older ones in same geographic area • 2 Explanations: • Lamarck’s • Darwin’s

  3. Jean Baptiste Lamarck • Thought acquired traits (learned, not inherited) could be passed to offspring • Not True!!

  4. Charles Darwin Spent 5 years aboard H.M.S. Beagle traveling world & recording observations • Animal adaptations and geographic changes required VERY LONG periods of time to occur

  5. Modern Evolutionary Thought • Natural Selection: organisms best suited to their environments will reproduce more successfully • Over time, # organisms with favorable traits increases within a population Artificial Selection: Breeding organisms with specific traits to produce desired offspring

  6. Modification by Natural Selection The Process: • 1) Organisms better equipped to survive environment will produce more offspring • 2) Eventually, popltn made up of only successful members • 3) Over time, an entirely new species may form!!

  7. Descent with Modification • “Newer forms appearing in fossil record are actually modified descendants of older species” • Implies that ALL species descended from only a few ancient organisms

  8. Adaptation • Populations adapt as their # of favorable traits increases • The types of traits that are favorable depends on the environment • Examples: • Mimicry:a harmless species resembles a dangerous one; both are avoided by predators • Camouflage:enables species to blend with surroundings • Penicillin-resistant bacteria, rose thorns, etc. • As genetic makeup of popltn changes, evolution occurs

  9. CAMOUFLAGE MIMICRY

  10. Patterns of Evolution • The pattern & speed with which organisms adapt is dependent upon their environment • 3 Patterns: • 1) Coevolution • 2) Convergent Evolution • 3) Divergent Evolution

  11. Coevolution • Coevolution: the change of 2 or more species in close association • i.e. predator/prey; parasite/host; plants/herbivores

  12. Convergent Evolution • Convergent Evolution:occurs when environment selects phenotype • Results in similar phenotypes of different organisms • i.e.: body shape of dolphin (mammal) & shark (fish)

  13. Divergent Evolution • Divergent Evolution:when 2 related species become more dissimilar • Adaptive Radiation: when different species evolve from common ancestor • i.e.: Galapagos finches

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