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Evolution

Evolution. The Earth has been home to living things for about 3.8 billion years. Evidence. Fossils – the remains of once living organisms preserved in the Earth Types of fossils: Hard Body parts (such as bones, teeth, shells ) Imprints in Sedimentary Rock. W hich rock layer is the oldest?.

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Evolution

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  1. Evolution The Earth has been home to living things for about 3.8 billion years.

  2. Evidence • Fossils– the remains of once living organisms preserved in the Earth • Types of fossils: • Hard Body parts (such as bones, teeth, shells) • Imprints in Sedimentary Rock

  3. Which rock layer is the oldest?

  4. Mass Extinction • A period when large number of species became extinct at nearly the same time. • Permian Era- 225 mya: 90% of marine life when extinct • Cretaceous Era – 65 mya. Disappearance of dinosaurs

  5. How did new species arise on Earth? • Evolution- the change of a species over a LONG period of time.

  6. We know today that the changes arise from genetic mutations or variations that are passed down from generation to generation. • But where did this idea come from?

  7. 2 Theories of Evolution • 1. Theory of Acquired Characteristics • The idea that a species can “get” a trait by passing it on to the next generation. • Lamarck!

  8. Lamarck thought that if an animal acquired a characteristic during its lifetime, it could pass it onto its offspring.

  9. Charles Darwin • Naturalists who published The Origin of Species after studying a variety of species on his voyage.

  10. 2. Theory of Natural Selection • Natural Selection – the best trait that is suited for the environment will allow a species to survive and reproduce at a higher rate

  11. The Beagle

  12. Darwin’s Voyage1831-1836

  13. The Galapagos Island (just read…) • Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos. • Giant tortoises varied in predictable ways from one island to another. • The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.

  14. The Galapagos Islands • Darwin collected the preserved remains of ancient organisms, called fossils. • Some of those fossils resembled organisms that were still alive today.

  15. The Journey Home • Darwin Observed that characteristics of many plants and animals vary greatly among the islands • Hypothesis: Separate species may have arose from an original ancestor

  16. Discovery of Genetics?!?!? • From 1856-63, a monk called Gregor • Mendel cultivated 29,000 pea plants • to investigate how evolution worked • i.e., how characteristics were passed • down the generations. • He figured out the basic principles of • genetics. He showed that offspring • received characteristics from both • parents, but only the dominant • characteristic trait was expressed. • Mendel’s work only came to light in • 1900, long after his death Mendel and his peas

  17. Four Factors that support Natural Selection • Adaptation- trait that allows species to survive and reproduce in a particular environment. • Selection– organisms with particular adaptations are most likely to survive and reproduce. • Overproduction– an abundance of offspring are produced, but not all survive. • Variation- results from mutations and increases the variety of traits in a species

  18. Evolution by Natural Selection • The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities • Survival of the Fittest-Some individuals better suited for the environment • Where food was limited, competition meant that only the fittest would survive. • This would lead to the natural selection of the best adapted individuals and eventually the evolution of a new species.

  19. Welcome to Shark Tank! • Which shark is the fittest?

  20. Natural Selection • Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment

  21. Evidence of Evolution • Fossilized Evidence • Similarities in Early Embryonic Development • Geographic Distribution of Living Things • Homologous Body Structures

  22. FossilizedEvidence

  23. Similarities in Early Development(look @ colorsheet)

  24. Evidence for Evolution • Vestigial organs - physical structures that were fully developed and functional in an ancestral group of organisms, but is reduced and unused in the later species. • So basically… organs that serve no useful function in an organism • i.e.) appendix, miniature legs, arms

  25. Homologous Structures • Similar structures that are related species have inherited from a common ancestor. • Ex- the bones in a bird’s wing, dolphin’s flipper, dog’s leg, human’s arm

  26. GENETIC EVIDENCE!!!

  27. Works Cited • http://www.pbs.org/wgbh/evolution/change/family/index.html • http://www.ucmp.berkeley.edu/education/explorations/tours/Trex/index.html • What did T-Rex taste like? • http://www.the-brights.net/images/TeacherRequest%20Form.pdf • http://www.nclark.net/Evolution#Activities

  28. Activity Natural Selection in the Peppered Moth

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