Evolution

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Evolution into the protista

• Modern Protista represent the first eukaryotes
• First eukaryotes evolved from prokaryote
  ancestors
• Modern Prokaryotes represent those ancestors
• How?

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Evolution of First Eukaryote(s)

• Forces leading to eukaryote
• Increases in size
• Increases in complexity

• Mechanisms
• Infolding of cell membrane
• Serial endosymbiosis of membrane-bound organelles
• Combination of the two

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Evolution of multicellularity

• Multicellularity evolved several times among the
  protista
• Complex, differentiated bodies evolved fewer
  times among the protista
• Brown, green and red seaweeds
• Slime molds (to be covered in the future)

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Multicellularity -colonies

• All cells the same
• Little or no differentiation in function
• Cooperation
• Volvox
• Filaments are a kind of colony
• May provide buoyancy

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Multicellularity -complex bodies

• Differentiation of tissues, organs
• Allows larger bodies
• Division of labor
• Requires more complex development
• Several times
• Seaweeds 3 lines, one to plants
• Fungi
• Animals

Kelp forest
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Evolution out of the protista

• Three exclusively multicellular kingdoms evolved
  from protistan lines (some multicellular, some
  not)
• Plants (from green algae)
• Animals (from flagellated protozoa
  choanoflagellates)
• Fungi (from flagellated protozoa
  choanoflagellates)
• When? Just before the Cambrian period
• Fungi 1100-800 mya (in sea, later joined plants
  on land)
• Animals 1100-800 mya (in sea)
• Plants 400 mya (on land)