lecture outlines for posting15

lecture outlines for posting15 - Lecture 15 - EEB 13 - 28...

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Lecture 15 - EEB 13 - 28 February 2008 Dr. Hespenheide macroevolutionary processes (adaptation, speciation, extinction) have created 3 major classes of patterns involving living organisms: history of life - today biogeography - next biodiversity - eventually - these will be treated in turn…. history of life - (Mayr, Ch.3) see summary handout at end of lecture macroevolution interacts with the evolution of Earth itself, and living organisms have caused changes in the Earth “Gaia hypothesis” (Mayr, p.42) - evolution of life and evolution of Earth are a single large system (Dr.H. supports only a weak version of this; that is, the effect of changes in the Earth on organisms has been much stronger than the effect of organisms on the Earth) five major features 1. origin of life on Earth during its formation, early Earth (4.5-4.0 bya) subject to bombardment by large objects, forming our moon, and perhaps the Earth’s water (from comets) – no life was possible, or if it was formed, was wiped out (it is possible that life arose more than once) life originated from non-living materials = abiogenesis [vs. alternative hypotheses of origin from space, creation…] scenarios for origin of life very speculative – happened 3.8 bya and there is no fossil record (first cells too small, no rocks on earth that old survive) we know how life turned out: life = self-reproducing (DNA) chemical systems (cells, needing energy for chemical reactions to occur) we also know there was only one successful (= surviving) origin of life, because all of life today shares DNA as the genetic material, the same triplet code, and other chemical similarities
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lecture outlines for posting15 - Lecture 15 - EEB 13 - 28...

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