Evolution & Evidences of Evolution

• Evolution


  Gradual process of change and development in living organisms over time.
• James Hutton


  Theorize the Theory of Geological Change in 1795
• James Hutton


  Father of Modern Geology
• Theory of Geological Change

  • Forces change Earth's surface shape
  • Changes are slow
  • Earth is much older than thousands of years
• Charles Lyell

  • Book: Principles of Geography
  • Geographical features can be built up or torn down
• Uniformitarianism


  The present is the key to the past
• Darwin thought...


  If earth changed over time, what about life?
• Jean Baptiste Lamarck's Theory of Evolution

  • Tendency toward Perfection (bird's using forearm)
  • Use and Disuse (Giraffe's Neck)
  • Inheritance of Acquired Traits
• First articulated theory of evolution:

  1. Organisms continually arise by spontaneous generation
  2. Organisms develop adaptations to changing environments through the use and disuse of organs
  3. Acquired characteristics are inherited
• Lamarck’s ideas were not widely accepted because they lacked evidence.
• Thomas Malthus

  • 19th century English Economist
  • If population grew --> insufficient living space & food runs out
• Thomas Malthus' Theory


  Darwin applied this theory to animals
• Evolution


  Process by which modern organisms have descended from ancient organisms
• Scientific theory


  Well-supported testable explanation of phenomena that have occurred in the natural world
• Voyage of the Beagle

  • Date: February 12, 1831
  • Captain: Charles Darwin
  • Ship: H.M.S. Beagle
  • Destination: Voyage around the world
  • Findings: Evidence to propose a revolutionary hypothesis about how life changes over time
• The Galapagos Islands


  Darwin's Living Laboratory
• Darwin was fascinated by the land tortoises and marine iguanas in the Galapagos.
• The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.
• Giant tortoises varied in predictable ways from one island to another.
• The smallest, lowest islands in the Galapagos were hot, dry, barren, and had sparse vegetation. Hood Island is an example.
• The higher islands had greater rainfall and a different assortment of plants, and animals, and had rich vegetation. Isabela Island is an example.
• Animals found in the Galapagos

  • Land tortoises
  • Finches
  • Blue-footed booby
  • Marine Iguanas
• Darwin observed that the characteristics of many plants and animals vary greatly among the islands.
• Darwin hypothesized that separate species may have arisen from an original ancestor.
• Russel Wallace's Essay


  Gave Darwin the drive to publish his findings through the book "On the Origin of Species"
• Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia.
• Natural Selection

  • Results in changes in inherited characteristics
  • These changes increase a species' fitness in its environment
• Natural Variation


  Differences among individuals of a species
• Artificial Selection


  Nature provides the variation among different organisms, and humans select those variations they find useful.
• The Struggle for Existence


  Members of each species must compete for food, shelter, and other life necessities.
• Survival of the Fittest

  Some individuals are better suited for the environment.
• • Darwin visited Argentina and Australia which had similar grassland ecosystems
  • These grasslands were inhabited by very different animals
  • Neither Argentina nor Australia was home to the sorts of animals that lived in European grassland
• Darwin collected the preserved remains of ancient organisms, called fossils.
• Some of the fossils resembled organisms that were still alive today.
• Descent with Modification


  Each living organism has descended, with changes from other species over time.
• Common descent


  Were derived from common ancestors
• Fossil Record

  • The layer that shows change.
  • Show extinct species.
  • Show relationships between current and ancient organisms.
• Biogeography


  The study of the geographic distributions of organisms
• Homologous Structures


  Structures that have different mature forms in different organisms, but develop from the same embryonic tissue.
• Homologous Structure


  Structures with similar anatomy but dissimilar functions