BIOL 226 Lecture Notes - Natural Selection, Global Cooling, Ocean Current
29 Jan 2014
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Document Summary
Past organisms were very different from those now alive: macroevolution is the pattern of evolution over large time scales, the fossil record shows macroevolutionary changes over large time scales including. Fossils reveal ancestral characteristics that may have been lost over time. The origin of new groups of organisms: mammals belong to the group of animals called tetrapods (four limbs, the evolution of unique mammalian features through gradual modifications can be traced from ancestral synapsids through the present. Key events in life"s history: the origins of single-celled and multicelled organisms, and the colonization of land. Oxygen revolution: most atmospheric oxygen (o2) is of biological origin, cyanobacteria perform oxygenic photosynthesis, oxygen in water increases, oxygen in atmosphere increases, major extinction of anaerobes. Endosymbiosis : the theory of endosymbiosis proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells (see fig 25. 9)
