Evolution

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					      Evolution

The cornerstone of modern
         biology
           Charles Darwin
• On the Origin of Species by Means of
  Natural Selection, 1859
• Overproduction
• Competition
• Variation
• Adaptation
• Natural selection
• Speciation
          Natural selection
• Selection based upon pressure from the
  environment; ex. harsh climate, lack of
  food, dark/light tree trunks
Black peppered moth on white
         tree trunk
Variation within the species of
       peppered moths
The long neck of the giraffe

    Height males 4.7-5.3 m; with an
 unusually heavy head (three times the
        weight of a cow’s head)
       Height females 3.9-4.5 m
         Why?

Natural or sexual selection?
          Sexual selection
• Selection based upon a careful choice by
  the opposite sex (often by the females),
  who favours certain traits
Awkward but gorgeous!
Gorgeous(?) but awkward!
       Evidence of evolution
• Fossils
• Living organisms – comparative anatomy
  and molecular similarities
• Chemical evolution – from chemicals to life
• Genetical studies – DNA-fingerprinting of
  species produces phylogenetic trees
                 Fossils
• Fossils in amber, ice and tar – more recent
• Petrified fossils (incl. footprints) in
  sedimentary rocks
• Relative vs. absolute geological dating
    Evidence from Living Organisms
•   Homologous structures
•   Analogous structures
•   Vestigial structures
•   Embryological similarities
•   Molecular similarities
Which geologic period?
Jurassic
Which geologic period?
Permian/Triassic
Which geologic period?
Carboniferous
Which geologic period?
Cambrian
Which geologic period?
Devonian
Which geologic period?
Tertiary/Quartenary

				
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posted:8/28/2012
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