mattebioreview

 

Evolution

Page history last edited by ellenberger_matt@... 1 yr ago

 

 

  • geologic time scale: an organized scale that divides the earth's history into 4 parts
    1. precambrian
    2. paleozoic
    3. mesozoic
    4. cenozoic
  • fossils: evidence that organisms lived long ago preserved in earth's rocks
    • trace fossils- indirect evidence that is left by an organism   ex. footprint
    • casts- when rocks or sediment fill in a space left by a decayed organism
    • molds- organism is buried in sediment and then decays, leaving an empty space
    • petrified- minerals sometimes penetrate and replace the hard parts pf an organism
    • permineralized- void spaces in origional organism infilled by  minerals
    • amber-preserved / frozen- entire organism was quickly trapped in ice or tree sap that has hardened into amber
  • realitive dating: scientists can tell how old a fossil is based on it's location in different layers of rocks. Fossils on the top of sediment are usually younger than the fossils on the bottom of the sediment
  • radiometric dating: scientists use radioactive isotopes to measure the age of fossils (half-life)
  • Charles Darwin:
    • wrote the famous book "On Origins of Species by Means of Natural Selection"
    • believed the result of natural selection was adaption, a feature that gives an organism an advantage from others
    • Theory of Evolution had 4 main points:
      1. every population has a variation within their genes
      2. some species in a population are better suited for survival that others
      3. traits that allow populations to survive tend to spread through the population
      4. evidence suggests that species have evolved from extinct organisms - "descent with modification"
  • Evidence of Evolution:
    1. Fossil Records
      • show patterns of development
    2. Anatomy and Develpoment
      • homologous structures
      • vestigial structures
      • analogous structures
    3. Embryology
      • see similarities within structures
    4. Biochemistry
      • proteins that are created by nucleic acids have fewer differences in their amino acid sequences than with similar creatures
  • Natural Selection: driven by four points
    1. all populations have genetic variation
    2. the environment presents challenges for successful reproduction
    3. individuals tend to produce more offspring than the environment can support
    4. individuals that are better able to cope with the challenges presented in the environment tend to leave more offspring than the those individuals less suited to the environment do
  •   speciation: process by which new species are formed
    • geographic isolation - mechanism of isolating organsims based on physical separation of members of a population
      • colonization - from the develpoment of a new area
      • new barrier - river of highway separates organism
    • reproductive isolation - formerly interbreeding organism can no longer mate of produce offspring
      • different genetic material of each organism makes it impossible for reproduction
      • behavior pattern allows organisms to reproduce at different times
  • Punctuated Equilibrium: Steven Jay Gould in 1972 suggested that speciation occurs quickly, in rapid bursts, with long periods of stability in between . Supported by fossil evidence
  • Gradualism: Darwin suggested that evolution proceeds at a slow rate, and small, adaptive change occurs over time. Supported by fossil evidence

Comments (0)

You don't have permission to comment on this page.

Printable version
 
Anonymous Create an account or Log in