October 4-ch18 - o Can be applied to sexually and asexually...

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October 4, 2007 Chapter 18 The Three domain system Bacteria (prokarya) Archaea (prokarya) Eukarya (eukarya) Kingdom-level classification No consensus among systematists regarding the precise definitions of new New information is discovered Systematists are always proposing new hypothesis Species Definitions change The biological species concept o A species is a group of interbreeding nature populations, which are reproductively isolated from other such groups o Cannot be applied to asexually reproducing organisms The Phylogenetic species concept o The smallest diagnosable group that contains all the descendants of a single common ancestor
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Unformatted text preview: o Can be applied to sexually and asexually reproducing organisms o May eventually replace the biological species concept How many species exist? • Bioderviersity is the total number of species in an ecosystem • 7-10 million species • Number of name species is currently about 1.5 million o 5% prokaryotes and protists o 22% plants and fungi o 73% animals • 7-10,000 species identified annually • Tropical rain forests o Home to 2/3 of the world’s existing species o Most not identified and named o Rapid rate of destruction o Species not yet identified probably being extirpated •...
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