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Introduction to Evolution

Introduction to Evolution. Section 5.1. Charles Darwin (1809-1882) a. “Father of Evolution” b. Much of his research comes from the Galapagos Islands, off the coast of South America. What did Darwin’s Travels reveal?.

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Introduction to Evolution

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  1. Introduction to Evolution Section 5.1

  2. Charles Darwin (1809-1882) a. “Father of Evolution”b. Much of his research comes from the Galapagos Islands, off the coast of South America

  3. What did Darwin’s Travels reveal? • The diversity of living species was far greater than anyone had previously known!! • The species, while different, had similarities to one another and to other species found in South America

  4. What Sparked Darwin’s Theory? • Each island had its own type of tortoises and birds that were clearly different from other islands • However, similarities existed between them

  5. Galapagos Tortoises

  6. What is Evolution? • Defined as change in a species over time • It proposes that organisms descended from a common ancestor • Organisms in a population differ slightly in form, function, and/or behavior. • These differences are due to hereditary changes in DNA passed down from parent to offspring.

  7. Darwin’s Theory of Evolution • Darwin proposed that the environment exerts a strong influence over which individuals will survive to produce offspring (“Survival of the Fittest”) • These individuals have certain traits that make them more likely to survive and reproduce. (based on genes) • Over time (many generations), natural selection causes the characteristics of a population to change.

  8. Evolution by Natural Selection • Organisms produce more offspring than can survive. • The environment is hostile and contains limited resources. • Organisms differ in the traits they have. • Some inherited traits provide organisms with an advantage. • Each generation contains proportionately more organisms with advantageous traits.

  9. Other Mechanisms of Biological Evolution: Mutation, Migration, and Genetic Drift Mutation Accidental change in DNA that can give rise to variation among individuals Migration Movement of individuals into (immigration) or out of (emigration) a population

  10. Genetic Drift Evolution that occurs by chance In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals.

  11. Artificial Selection • Nature provides variation- humans select the variations that are useful to them. • Example - a farmer breeds only his best livestock

  12. Speciation • Process by which new species are generated • Can occur in a number of different ways; the most important way is called allopatric speciation • Has resulted in every form of life on Earth-today and in the past

  13. Extinction • The disappearance of species from Earth • Generally occurs gradually, one species at a time, when environmental conditions change more rapidly than the species can adapt • There are 5 known mass extinction events, each of which wiped out a large proportion of Earth’s species.

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