chapter 25 - Understanding evolution Phylogeny Systematics...

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1 Understanding evolution Phylogeny Systematics evolution : gradual process by which the universe changes; it includes the origin of life, its diversification, and the synergistic phenomena resulting from the interaction between life and the environment” The Tree of Life Phylogeny Æ evolutionary history of a group of related taxa Systematics Æ analytical study of the diversity and evolutionary relationships of taxa The Tree of Life domains: bacteria, archaea, eukarya Symbiosis of chloroplast ancestor with ancestor of green plants Bacteria Eukarya Archaea ears ago 0 1 2 4 Symbiosis of mitochondrial ancestor with eukaryotes Possible fusion of bacteria and archaea yielded eukaryotes Common ancestor of all organisms Billion ye Origin of life 3 4 1 2 3 orangutan gorilla bonobo chimpanzee Divergence of human and ape species Pääbo 2003 Nature 421 Hominid "Family Tree": This evolutionary tree depicts lines of possible descent for hominids. It proposes relationships among species over time. Trees are hypotheses based on comparison of living species, fossils, and genetic data. Source AMNH-New York 2007
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2 Phylogenies are based on common ancestry Evidence: Fossil record Morphology / physiology Molecular (DNA, RNA, amino acid sequences) How fossils form and get trapped in sediments Rivers carry sediment to the ocean. Sedimentary rock layers containing fossils form on the ocean floor. Oe rt imene s t ra taa re Over time, new strata are deposited, containing fossils from each time period. As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion reveals strata and fossils. Younger stratum with more recent fossils Older stratum with older fossils Petrified trees in Arizona, about 190 mil ion years old Leaf fossil, about 40 mil ion years ago Dinosaur bones being excavated from sandstone Casts of ammonites, about 375 mil ion years old Boy standing in a 150-mil ion-year-old dinosaur track in Colorado Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice Insects preserved whole in amber (Ba) (Ba) (Ba) Dalrymple, G. B. 2007. The ages of the earth, solar system, galaxy, and universe. (Ba) (Ba) Phylogenies are based on common ancestry Evidence: Fossil record Morphology / physiology Molecular (DNA, RNA, amino acid sequences) Homologous Anatomical Structures Æ common descent Human Cat Whale Bat
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3 Pterosaur convergence Analogous morphology / physiology Æ Butterfly Bat Analogous Anatomical Structures Æ convergence Marsupial Australian mole Eutherian mammal North American mole Thylacinus cynocephalus Became extinct in 1936 Thylacinus cynocephalus http://www.skul site.co.uk/Thylacine/thylacine.htm Siberian Wolf Phylogenies are based on common ancestry Evidence: Fossil record Morphology / physiology Molecular (DNA, RNA, amino acid sequences)
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4 Can DNA , RNA , or amino acid sequences change over time?
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This note was uploaded on 04/16/2008 for the course BIO 131 taught by Professor Paz y mino during the Fall '08 term at UMass Dartmouth.

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chapter 25 - Understanding evolution Phylogeny Systematics...

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