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BIO 358: CETACEAN EVOLUTION
What are the two "plans" to analyze their evolution?
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1. Fossils
2. Molecular data
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What is important to look for if cetacean evolution is using the fossil record?
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Look for things that look more terrestrial
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Why is it a "narrow window" when using molecular data to see evolutionary history?
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1. morphology not required
2. identifies relationships of extant species only
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Before September 2001, cetaceans are most closely related to ____ using the FOSSIL DATA
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mesonychids
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Before September 2001, cetaceans are most closely related to ____ using the MOLECULAR DATA
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Artiodacyls
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What is the synapomorphy for mesonychids?
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Specialized teeth (carnivorous diet)
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What is the synapomorphy for artiodactyls?
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Specialized astragulus (limits ankle movement)
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What is an artiodactyl?
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Even-toed ungulates
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What is the astragalus?
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Bone that permits a wide range of movement in ankle
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Why is the astragalus limited in cetaceans?
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helps elongate the leg instead
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who is the oldest known cetaceans?
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Pakicetus
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What relative did Gingrich 1983 believe was related to Pakicetus?
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Mesonychids
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Why did Gingrich 1983 believe mesonychids were related to Pakicetus?
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No preserved hindlimb, teeth similar to mesonychids
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Who was the ancient ancestor to possess a cetacean bulla?
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Ambulocetus natans
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What scientist described Ambulocetus natans?
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Thewissen 1994
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Who was the "walking whale" and who described it?
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Ambulocetus natans; Theswissen 1994
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Why did Thewissen 1994 call Ambulectus natans a relative to mesonychids?
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No ankle bones, teeth like mesonychids
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Fossil evidence supports close relationship between cetaceans and....
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mesonychids
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Who was the first to use a molecular character called SINEs?
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Shimamura 1997
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Who used regions of the host genome where viral RNA had been incorporated in his SINEs
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Shimamura 1997
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Why did Shimamura 1997 decide to use SINEs???
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Probability of INDEPENDENT insertions occurring in SAME place in DIFFERENT clades almost ZERO
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What did Thewissen 2001 discover?
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New Pakicetus fossils, including ankles, pelvis, and vertebrae
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Broad base of general undulates, considered to be ancestor to the current undulates
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Condylarthra
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5 characters for the representative mesonychid?
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1. standing up on middle toe
2. ungulates with hooves
3. wolf-sized
4. cursorial --> runners
5. predators
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What did Thewissen 2001 discover and then conclude about Pakicetus?
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Astragalus and Calcaneous. Looks like artiodactyl
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What was the traditional view Pre-1994
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Artiodactyls are a monophyletic clade and cetaceans are the most closely related sister group
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Who did Pre-1994 come to their "traditional view"
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Early molecular data of protein sequencing
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Who in 1994 used mitochondrial & nuclear genome data to evaluate cetacean-artiodactyl relationships?
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Graur and Higgins
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What did Gaur and Higgins 1994 use?
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mitochondrial & nuclear genome
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What did Gaur and Higgins 1994 reveal?
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Artiodactyls are traditionally defined as PARAPHYLETIC, not including cetaceans (in the middle of tree)
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What did Shimamura 1997 define the relationships?
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Traditionally defined artiodactlys as paraphyletic. (doesn't include cetaceans, which are most recent)
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What did Thewissen 2001 describe as relationship?
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Monophyletic = Cetartiodactyla. Both include specialized astragalus.
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Both ___ and ___ support close relationship between cetaceans and artiodacyls
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fossils and molecular data
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