Darwin

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Darwins Theory of Evolution

• The Puzzle of Lifes Diversity

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Evolution Change over time

• Charles Darwin Voyage of the HMSBeagle
• Darwin was a naturalist
• In his voyage around the world he made
  observations of living things.
• These observations led him to question why there
  were so many organisms that appeared to be of the
  same species but, very different.
• His observations led to his theory of evolution
  about how living things change over time.

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Darwins Observations

• Diverse species of organisms appeared to be well
  suited to their environments
• There are different ways of reproducing.
• He determined that there were patterns of
  diversity.
• Why were there no rabbits in Australian
  grasslands and no Kangaroos in European
  grasslands.

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Living Organisms and Fossils

• Darwin realized that fossils also contributed to
  the earths diverse species.
• Fossil preserved remains of ancient organisms
• Darwin studied fossils
• Some resembled living organism
• Some looked like nothing that he had ever seen
• Why had they disappeared?
• How are they related?

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Galapagos Islands

• The Galapagos are a chain of volcanic islands
  found 500 miles off of the coast of Ecuador.
• The Islands are close together yet had very
  different climates, terrain and vegetation.
• Because of the environmental differences there
  were diverse yet related species found.

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Galapagos Tortoises
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Galapagos Finches
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Geological Support for Evolution

• Geologist Hutton and Lyle helped to contribute
  to Darwins theory because
• They were the first to question the age of the
  earth
• Hutton proposed that layers of rock are formed
  over long periods of time by geological forces
  for example, plate tectonics and rain, heat and
  cold.
• The earth must be millions of years old and not
  thousands as once believed

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Geology continued

• Lyells Principles of Geology
• Earths past processes that shaped the earth are
  no different from present processes.
• Volcanoes, earthquakes, and erosion

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Lamarcks theory of Evolution

• First evolutionist to theorize that living things
  change over time.
• Proposed that selective use or disuse of an organ
  leads to the organism acquiring or losing traits
  during their lifetime that could be passed on to
  their offspring.

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Lamarck

• Tendency toward perfection
• Organisms continually change and acquire new
  traits to be better suited to their environments
• The more birds fly the bigger their wings get
• Use/Disuse
• Birds could transform forelimbs into wings for
  flying or if they didnt use their wings they
  would eventually become smaller until they
  disappeared.
• Inheritance of acquired traits
• Lamarck thought that all of these acquisitions
  could be passed on to offspring

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Population Growth

• Reproduction has a significant role in evolution
• Thomas Malthus reasoned that unchecked human
  population growth would result in famine and
  disease

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Darwin and Malthus

• Darwin realized that Malthus was correct in his
  reasoning and suggested that his idea applied
  more to plants and animals more so than humans.
• Darwin theorized that organisms reproduce in
  large numbers because only a few survive and
  reproduce.
• Organisms must compete for resources.
• There is a struggle for existence to obtain food,
  living space and other necessities of life.

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Artificial Selection vs. Natural Selection

• Selective breeding based on natural variation is
  artificial selection.
• Farmers and breeders select the best
  characteristics of species and breed new species
  carrying the best traits of both parents.
• Natural selection takes place without human
  interference.

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Natural Selection and Adaptation

• The ability of an organism to survive and
  reproduce in its environment describe its
  fitness.
• Fitness is a result of adaptations, any inherited
  characteristic that increases the chance for
  survival.
• Adaptations can be physical or behavioral.
• Organisms that have characteristics that are not
  suited to their environment are unable to
  survive. Survival of the Fittest

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