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Evolution

Evolution . Chapter 15: Darwin’s Theory of Evolution Chapter 16: Evolution of populations. Standard 5: Evolution and Biodiversity Central Concepts: Evolution is the result of genetic changes that occur in constantly changing environments. Over many generations, changes in

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Evolution

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  1. Evolution • Chapter 15: Darwin’s Theory of Evolution • Chapter 16: Evolution of populations

  2. Standard 5: Evolution and Biodiversity Central Concepts: Evolution is the result of genetic changes that occur in constantly changing environments. Over many generations, changes in the genetic make-up of populations may affect biodiversity through speciation and extinction. 5.1 Explain how evolution is demonstrated by evidence from the fossil record, comparative anatomy, genetics, molecular biology, and examples of natural selection. 5.2 Describe species as reproductively distinct groups of organisms. Recognizethat species are further classified into a hierarchical taxonomic system (kingdom, phylum, class, order, family, genus, species) based on morphological, behavioral, and molecular similarities. Describe the role that geographic isolation can play in speciation. 5.3. Explain how evolution through natural selection can result in changes in biodiversity through the increase or decrease of genetic diversity within a population

  3. 15.1 Life’s Diversity * In 1831, Charles Darwin set sail on a voyage around the world to observe the natural world. HMS Beagle. * He observed many samples of plants & animals and noticed a lot of variation. • It was during this voyage that Darwin developed the the ideas leading to his “hypothesis of evolution” - as a way leading to the change of life over time. The Voyage

  4. The Theory of Evolution started out as a hypothesis. • As more research, testing, and data were collected, Darwin’s hypothesis about change became the Theory of Evolution. * theory: well-supported & testable explanation of a phenomenon that occurs in the natural world. evolutionary theory • Evolution, or change over time, is the process by which modern organisms have changed and become more diverse and stem from common ancestors

  5. * Observations that Darwin made on his journey which helped to shape his theory: A. Diversity: - Many types of organisms. - Each well adapted to live in their environment. - Some organisms were missing from similar ecosystems in different parts of world. Why?

  6. B. Fossils: - organisms not around now but similar to modern organisms. - other fossils looked nothing like anything he had seen • fossils on D's voyage

  7. Galapagos Islands: - Darwin observed that the Galápagos Islands were close together but had very different climates - organisms (finches) varied from island to island

  8. Darwin wondered if animals living on different islands had once been members of the same species. These separate species would have evolved from an original South American ancestor species.

  9. Giant Tortoises of the Galapagos Islands Section 15-1 Pinta Tower Pinta IslandIntermediate shell James Fernandina Santa Cruz Santa Fe Hood Island Saddle-backed shell Isabela Island Dome-shaped shell Different shells on tortoises from neighboring islands

  10. 15.2 More ideas that shaped Darwin’s thinking A. James Hutton & Charles Lyell earth is older than thought changing constantly. B. Jean Baptiste Lamarck (1744 – 1829) Thought organisms changed in response to enviromnent * organisms acquired a trait in it’s lifetime if it was helpful for it’s survival & lost it if it was not necessary for survival. A body part might get smaller and disappear if not used. * once acquired, the trait could then be passed on to offspring. * the change occurred by using a body part in a new way

  11. Lamarck’s idea of “use & disuse” • Male uses his claw to attract mates & defend • Because it used, it slowly grows larger • This acquired trait is passed on to his offspring We know that this idea was found to be incorrect

  12. giraffes

  13. Thomas Malthus (1798) – Population Growth * Human birthrate is higher than the death rate. * Eventually we will run out of living space and food. * Famine , disease, and war control populations. PBS Malthus/Darwin Darwin & Malthus Darwin wondered : Plants & animals have more offspring than humans and yet don’t take over the world. So…….. What causes the death of so many plant & animal offspring ? What determines which ones survive to reproduce and which ones don’t?

  14. 15.3 Darwin’s Theory of Evolution • In 1858, Darwin received a short essay from naturalist Alfred Wallace. • The essay summarized Darwin’s thoughts on evolutionary change. • Later that year, Wallace’s essay was presented with some of Darwin’s work. • In 1859, Darwin published his book, On the Origin of Species.

  15. Evolution – the basic concept…….. Survival of the Fittest 1. Organisms with in species have variations. 2. Organisms must compete for resources (food/mates) 3. In an effort to survive, organisms with beneficial adaptations or characteristics for that environment are considered “fit”. 4. These individuals will survive to reproduce and pass on the genes for these beneficial adaptations. Adaptations: A million different possibilities, depending on what is needed to be fit in that particular environment

  16. Adaptations bee & orchid = mimicry eyes Hair Mating calls Find more examples Examples where environment changes

  17. Darwin developed his idea of “natural selection” after observing farmers “artificially select” the “best” plant and animals for breeding. Examples: redder tomatoes, milkier cows disease resistant foods He thought that maybe nature could “select” organisms based on their “fitness” too. Peppered Moths

  18. Descent with Modification Over long periods of time, natural selection produces organisms with different structures, niches, habitats, and behaviors. As a result, species today look different from their Ancestors = EVOLUTION Common Descent A single tree of life connects all living organisms

  19. Evidence for Evolution • Fossils remains of living organisms. The “fossil record” shows life has changed over time.

  20. B. Geographic distribution of organisms individuals in different geographical places – like islands, have same species with slight differences. Galapagos finches.

  21. Homologous body structures Body parts that have different functions but are similar in structure and have similar embryonic development.

  22. Embryonic Development similarities in structure and development of embryos gives evidence of a common ancestor • NOVA Online/Odyssey of Life/Morphing Embryos

  23. Comparative Embryology

  24. E. Vestigial organs: appendix hind legs in whales human tailbone the blind fish wisdom teeth F. Biochemistry & DNA Similar DNA indicates a relatedness and common ancestors

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