Lec 33 2B F09 - BIS2B Fall 2009 (Keen) Lecture 33....

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BIS2B Fall 2009 (Keen) Lecture 33 . Evolutionary time scales 25 November Students should be able to: Explain the relationship between speciation events and the tree of life. Explain the relationship between lineage splitting and classification. Explain how the idea of successive change is shown on a cladogram. Give an example of an ancient and a modern symbiosis.
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The Earth is old: 4.5 billion years (by) old Life has been around for a long time: 3.5 by First life was in the seas of the Hadean eon We presume it was a bacteria-like cell The population of early cells increased and spread
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Bacterial lineage 3.5 bya How would the population grow at first? Why would it change its growth trajectory? There may have been many kinds of life, but only one (LUCA) left descendants
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Bacterial lineage 3.5 bya Common ancestor of Archaea and Eukarya First lineage split or speciation event
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Hadean eon 3.5 billion years ago First eukaryote 2.5 -1.5 billion years ago Bacterial lineages split many times; lots of evolution in these forms over the last 3.5 billion years Archaeal lineage split many times
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Hadean eon 3.5 billion years ago First eukaryote 2.5 – 1.5 billion years ago Unicellular eukaryote lineages Multicellular eukaryotes ?1 billion years ago
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For most of this era, life was microscopic, prokaryotic, and living in oceans. Eukaryotes evolved about 2/3 through the Precambrian.
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This note was uploaded on 04/21/2010 for the course BIS 2C BIS 2C taught by Professor Rizzo during the Winter '09 term at UC Davis.

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Lec 33 2B F09 - BIS2B Fall 2009 (Keen) Lecture 33....

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