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Theory of evolution

Theory of evolution. Chapter 15. Evolution . Development of new organisms from pre-existing ones Heritable change in the characteristics within a population from one generation to the next Charles Darwin published “ O n the Origin of the Species ” in 1859

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Theory of evolution

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  1. Theory of evolution Chapter 15

  2. Evolution • Development of new organisms from pre-existing ones • Heritable change in the characteristics within a population from one generation to the next • Charles Darwin published “On the Origin of the Species” in 1859 • descent with modification (DwM)

  3. Descent with modification (DwM) • Every species must have descended by reproduction from preexisting species • Species must be able to change over time

  4. Natural selection • Mechanism for DwM • Four main parts of Darwin’s reasoning • Overproduction: more offspring produced than can survive • Genetic variation: individual within a population have different traits • Struggle to survive: individuals compete • Some variations improve chance for survival and reproduction • Adaptation: trait that makes an individual successful in its environment

  5. Natural selection 4. Differential reproduction: organisms with best adaptations are most likely to survive and reproduce • Through inheritance, adaptations become more frequent in a population • This leads to change in a population • Fitness: measure of an individual’s heredity contribution to the next generation • More than survival • Must reproduce offspring that will reproduce in turn • Notebook assignment: See page 300

  6. Contributors to Darwin • Before Darwin’s time, most scientist thought the earth and it’s organisms were permanent and unchanging • Earth was thought to only be thousands of years old • How old is it actually? • About 4.5 Billion years old • Geologists started to identify the actual age of the earth by looking at the rock strata: rock layers • Oldest layers on bottom

  7. Contributors • French anatomist Georges Cuvier • Reconstructed fossils • Some organisms in the past differed greatly form any living species • “sudden changes” result of catastrophism >> caused extinction • English geologist Charles Lyell • Uniformitarianism • the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes • French biologist Jean Baptiste Lamarck • INHERITANCE OF ACQUIRED CHARACTERISTICS • is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring

  8. Inheritance of Acquired Characteristics

  9. Fossil record • Fossil: remains or traces of past life • Fossils show that different organisms have appeared at different times and places on Earth • Superposition: oldest rocks on the bottom

  10. How old is it? • Relative vs absolute age • Which is older: A fossil at A or F? • If a radioactive isotope has a half-life of 50 years, how much is left after 250 years if the original amount was 5,000 mg?

  11. Transitional species • Intermediate species between ancestral species and later descendants • Page 304

  12. Biogeography • Studies why living things are found where they are • Unrelated organisms with similar features

  13. Comparative anatomy • Homologous structures: found in related species that share a common ancestor • May have different functions but similar structure • Analogous structures: related functions, but different structure

  14. Vestigial structures • Structures with no current function • May have been functional in ancestral species

  15. Evolution in action • Evolution is continuous and ongoing • Scientists can study evolutionary patterns today • Case study: anole lizards • Page 308

  16. Convergent evolution • Process by which different species evolve similar traits

  17. Divergence and radiation • Divergent evolution: process in which descendants of a single ancestor diversify into species that each fit into different parts of their environment

  18. Adaptive radiation • Many species evolve from a single ancestral species

  19. Artificial selection • Selective breeding of organisms for specific traits • DONE BY HUMANS!!! • This is in contrast to natural selection in which the environment places pressure on certain traits

  20. Coevolution • When two or more species have evolved adaptations to each other’s influence • Why are flowers different colors? • Why do they have different scents? • Why are flowers shaped differently? • Why do we keep having to develop new antibiotics? • Methicillin Resistant Staphylococcus aureus • MRSA

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