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Modern Evolution

Modern Evolution. History of Life on Earth. The Earth is thought to be about 4.6 billion years old. The oldest rocks on Earth have been dated at 3.9 – 4.28 billion years old. Rock’s located on the Canadian Shield, in Hudson’s Bay. So How Do We Know How Old The Earth Is?.

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Modern Evolution

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  1. Modern Evolution

  2. History of Life on Earth • The Earth is thought to be about 4.6 billion years old. • The oldest rocks on Earth have been dated at 3.9 – 4.28 billion years old. • Rock’s located on the Canadian Shield, in Hudson’s Bay.

  3. So How Do We Know How Old The Earth Is? • Using radioactive decay analysis, you can find out the age of rocks on Earth. • Unstable radioisotopes lose atomic particles and become a new isotope. • Every isotope has a specific half-life which tells you how old the sample is.

  4. Carbon-14: 5, 714 years • Uranium-234: 80, 000 years • Potassium-40: 1.3 billion years • Rubidium-87: 50 billion years

  5. Modern Evolutionary Synthesis • Combination of evolutionary theories incorporating all fields of biology. • Mutations are the Source of the Variation • Changes in DNA create variation • Could be extra/lost copies of chromosomes or genes

  6. Paleontology • Better understanding of plate tectonics, leading to continental drift, formation of mountains, volcanoes, etc.

  7. Better dated fossils show the basic pattern that organisms get more complex over time.

  8. So What Was The Earliest Life? • First known cells from stromatolites (ancient fossils) in Australia, constructed from anaerobic cyanobacteria~3.5 b.y.a. • Played a large role filling our atmosphere with usable oxygen.

  9. Another influence isEndosymbiosis; a single celled organism absorbs and incorporates another organism (e.g. inclusion of chloroplast and mitochondria in plant cells).

  10. As the environmental conditions changed, organisms are forced to adapt or die. • Evidence of mass extinctions worldwide, have traditionally triggered a change in the diversity of life on Earth.

  11. How Fast Is Evolution?? • Punctuated equilibrium– rapid changes followed by little change • Gradualism– many small ongoing changes occur

  12. Depending on the amount of time separating evolution between two species, the differences between the species will be more or less noticeable. • A phylogenic treecan show this:

  13. What Affects Changing Species • The formation of new species is called speciation. • Some factors that can affect species change: • Reproductive isolation – prevents interspecies mating due to: • Isolation (locations, mating times) • Behaviours • Physical/Genetic incompatability

  14. Genetic Drift • Random change in alleles for a trait in the population.

  15. Bottleneck / Founder Effect • Drastic drop in population that is re-built by a limited number of individuals • Decreased variety

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