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Evolution Outline

  • Word Count: 1436
  • Approx Pages: 6

             • Geographic distribution of living things
             • Homologous structures of organisms
             • Similarities in early development
             • Darwin proposed that Earth was millions of years old, not thousands.
             • During those millions of years, many different forms of species appeared, lived for a time, and then vanished leaving behind remains, or fossils.
             • One can examine fossils and view the changes of each one; observe the changes in offspring.
             • Each species is slightly different on Island A. Far away, on Island B, the species were also slightly different.
             • The species had changed over time as the populations in different places adapted to local environments.
             • The species had descended with modifications from a mainland ancestor – when Island A and Island B were combined as a contiguous land mass.
             • Different species exist on Island C and Island D. Similar structure and behavior were found in different animals which roamed similar environments.
             • As a result, one can conclude that the species now living on different islands had descended from different ancestors.
             • Some species, however, are similar because they were living under similar ecological conditions and thus exposed to similar pressures of natural selection.
             - Different animals ended up evolving certain striking features in common.
             • Look at mammals, reptiles, and birds; each of those creatures has backbones. There are striking similarities, like limbs.
             - Some limbs are arms, some are legs; they can also be wings, or even flippers. Each limb has a different form and function, but all are composed of the same basic bones.
             • Each limb had adapted in ways so the organism can survive in different conditions.
             • Despite the different functions, limb bones all developed from the same clumps of cells in growing embryos; these are called homologous structures.
             - Homologous structures provide evidence that all four-limbed animals with ba...

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Evolution Outline. (1969, December 31). In MegaEssays.com. Retrieved 02:42, August 24, 2016, from http://www.megaessays.com/viewpaper/22587.html