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Evolution:

Evolution:. Why Are There So Many Living Things?. Where Did the Idea of Evolution Come From?. Middle Ages: “Ladder of Life” Complex organisms found at highest rungs Less complex at lower rungs 1800’s Georges Cuvier brought study of fossils to the level of science.

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Evolution:

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  1. Evolution: Why Are There So Many Living Things?

  2. Where Did the Idea of Evolution Come From? • Middle Ages: • “Ladder of Life” • Complex organisms found at highest rungs • Less complex at lower rungs • 1800’s • Georges Cuvier brought study of fossils to the level of science.

  3. Where Did the Idea of Evolution Come From? • Charles Lyell • Proposed theory of uniformitarianism. • Jean-Baptiste Lamarck • Published theory of the inheritance of acquired characteristics.

  4. Charles Darwin • Loved nature • Studied medicine • Struggled with the inhumane operating procedures • Switched to religion • Offered position as naturalist on British survey ship, TheBeagle.

  5. Voyage around the World • Studied animals and fauna. • Noticed South American fossils differed from contemporaries. • Collected data for 27 years to support his mechanism for evolution.

  6. Fathers of Evolution • Alfred Wallace studied in Brazil and East Indies. • Developed mechanism of evolution independently of Darwin. • Sent a copy of it to Darwin. • Contained same conclusions as Darwin • Both presented their data at Linnaean Society of London in July 1858.

  7. How Did Darwin Account for Species? • In Origin of Species, he developed two main concepts • Evidence that evolutions has occurred. • Mechanism for evolution :natural selection.

  8. Major points of Darwin’s theories of evolution and natural selection • First observation: • Populations have the potential to increase exponentially. • Based on thoughts by Thomas Malthus

  9. Major points of Darwin’s theories of evolution and natural selection • Second observation: • Populations are fairly constant in size.

  10. Major points of Darwin’s theories of evolution and natural selection • Third observation: • Natural resources are limited. • Limited amount of space, nutrients, shelter • Results in competition for resources to survive.

  11. Major points of Darwin’s theories of evolution and natural selection • Deduction one: • Only some organisms survive. There is a struggle for existence among individuals in a population. • Organisms posses characteristics that enhance survival • Called adaptations.

  12. Three Types of Adaptations • Morphological-anatomical: modifications in form and structure that enhance survival. • Biochemical-physiological: modifications in the production and use of chemicals by organisms. • Behavioral Adaptations: Modifications in animal interactions with others and environment.

  13. Major points of Darwin’s theories of evolution and natural selection • Fourth observation: • There is variation within individuals of a population and variations are inherited.

  14. Major points of Darwin’s theories of evolution and natural selection • Deduction two: • Individuals with favorable variations are more likely to survive and reproduce. • Natural Selection: • “preservation of favorable variations and the rejection of injurious variations”

  15. Major points of Darwin’s theories of evolution and natural selection • Deduction three: • Accumulation of inheritable variation over many generations is evolution. • If changes within a species become great enough, a new species can result.

  16. What is a species? • Species are considered extinct if they do not interbreed in nature. • Implies offspring must also be able to reproduce.

  17. Evidence supporting Theory of Evolution • Selective breeding practices used by farmers result in: • “improved” domesticated plants and animals. • Darwin wondered if nature could do the same.

  18. Evidence supporting theory of evolution • Fossil record • Comparing fossils from ancestors with today’s species demonstrates species have evolved.

  19. Evidence supporting theory of evolution • Homologous structures • Structures dissimilar in form and function. • but share underlying structural similarities • Similarity due to a common ancestor?

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