jimtrue.com : school : BSC2011L : Lab 12: Principles of Evolution

Posted by Jim True on November 30, 2004 2:17 PM. Last Updated October 22, 2006 9:23 PM

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Lab 12: Principles of Evolution

Darwin's Concept - Natural Selection Drives Evolution

  1. All populations of organisms (all members of ONE species in ONE place at ONE time) exhibit variations that may be passed on.
  2. Growth of any population mathmatically can be shown to grow faster than that of available resources. If all offspring survive then resources are overwhelmed THEREFORE not all offspring can survive. Struggle for survival results.
  3. Some individuals in a population have variations that allow them to survive better in current environment. They exhibit fitness (innate ability or combination of factors that help the organisms to survive within the environment); the variations have adapted them for survival.
  4. The fitter individuals survive and pass their fitness to succeeding generations --> Descent with modification.
  5. Variations are largely induced by environment (nature). Since survivors of particular environment exhibit fitness, environment (nature) "selects" survivors --> Natural Selection.
  6. Over time (long periods of time), accumulated variations change organism into new and different forms (species).

Examples of the evidence for evolution

  1. the fossil record - when fossils are arrayed in the order of their age, a progressive series of changes are seen.
  2. The molecular record - The longer organisms have been separated according to the fossil record, the more difference are seen in the structure of their DNAs and proteins.
  3. Homology - All vertebrates contain a similar pattern of organs, arguing that they are related to one another.
  4. Development - During intrauterine development, human embryos and fetuses exhibit characteristics of other vertebrates, which suggests that humans are related to the other forms.
  5. Vestigial structures - many vertebrates contain structures with no function, but which resemble functional structures of other vetebrates, suggesting that the structures are inherited from a common ancestor.
  6. Parallel adaptation - The marsupials in Australia closely resemble the placental mammals of the rest of the world, which argues that parallel selection has occurred.
  7. Patterns of distribution - Inhabitants of oceanic islands resemble forms of the nearest mainland but show some differences, which suggests that they have evolved from mainland migrants.

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