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Evolution

Evolution. Change in life on Earth. Evolution. Phylogeny : the evolutionary history of a group of organisms . Often drawn as a tree. Charles Darwin. English naturalist Traveled the world for 5 years on the HMS Beagle

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Evolution

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  1. Evolution Change in life on Earth

  2. Evolution • Phylogeny : the evolutionary history of a group of organisms. • Often drawn as a tree

  3. Charles Darwin • English naturalist • Traveled the world for 5 years on the HMS Beagle • Darwin first produced evidence of evolution of living things from a common ancestor

  4. Charles Darwin • Darwin identified natural selection as the process for evolution. • Natural selection : mechanism for change in populations.

  5. Natural Selection • Natural selection proceeds in steps • 1. In nature, organisms produce more offspring than can survive. (overproduction)

  6. Natural Selection • 2. Individuals have variations. • This may be color, size, or speed

  7. Natural Selection • 3. Individuals with certain useful characteristics (variation) survive in a struggle for existence.

  8. Natural Selection • 4. Over time, the more successful variations are “selected” and the species will gradually change.

  9. Natural Selection • This gradual change in characteristics changes the population’s gene pool. • Gene pool: all available genes for a population

  10. Evidence of Evolution • Fossils provide a record of early life. • Fossils of a species can show change over time.

  11. Evidence of Evolution • Homologous structures: structures with the same evolutionary origin. • Can be the same in arrangement, function or both.

  12. Evidence of Evolution • Embryology : the study of the developing embryo. • The shared features of the young embryos suggest evolution from a common ancestor.

  13. Evidence of Evolution • Vestigial structures: a structure in a present day organism that no longer serves its original purpose. • Probably useful to its ancestor

  14. Evidence of Evolution • Biochemical : nearly all organisms share DNA, ATP and many enzymes. • The code for aminoacids is the same in organisms. • The more similar the DNA between 2 organisms, the more closely related

  15. Results of Natural Selection • Speciation : new species is formed when similar populations no longer interbreed. • Species: group of organisms that can breed and reproduce • Some obstacle may separate populations.

  16. Results of Natural Selection

  17. Results of Natural Selection • Diversity : a large variety of organisms. • The more diversity the healthier the ecosystem.

  18. Results of Natural Selection • Genetic Drift: Change in genefrequency. (how often you see a trait) • Especially in small populations. • Recessive trait is expressed • Results in a decrease in diversity.

  19. Polydactyl

  20. Results of Natural Selection • Divergent evolution: related species become less alike.

  21. Results of Natural Selection • Convergent evolution: unrelated species become more alike.

  22. Results of Natural Selection • Extinction : species may vanish • Can be a mass extinction like dinosaurs.

  23. Paths of Evolution • Gradualism : gradual change over time in a species Which fossils are the oldest?

  24. Paths of Evolution • Punctuated equilibrium: relatively quick evolution followed by long periods of equilibrium. • Big change in environment, or new predator

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