Geo 405 October 10th Lecture
Geo 405 October 10th Lecture GEO 405
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This 4 page One Day of Notes was uploaded by Kathleen Oh on Sunday February 1, 2015. The One Day of Notes belongs to GEO 405 at University of Texas at Austin taught by Dr. Julia Clarke in Fall. Since its upload, it has received 80 views. For similar materials see Life Through Time in Geology at University of Texas at Austin.
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Date Created: 02/01/15
Geo 405 October 10th Lecture Macroevolution 1 Macroevolution evolution on a grand scale what we see when new look at the overlong history of life a Questions to Ask i What are largescale trends over long stretches of geologic time ii Reducible to microevolution b First part processes that drove major change i Mutation Gene Flow Genetic Drift Natural Selection 1Similar features may be present in 2 species not due to a common ancestry as a result of 2 evolutionary events 2How can this pattern this pattern be generated by natural selection aNatura selection acting on inherited traits in similar environmental conditions may factor similar traits i Similar but unrelated animals in same environments ii Environmental factors lead to natural selection removing organisms that do not have traits that aid in surviving in the speci c environment bOrganisms with different tail size example i Natural selection is the removal of an existing variation in a population unfolds in a signi cant amount of time 3Relating phylogenetic systematics to natural selection aOn a cladogram branchesnodes in the different clades i So animals may be similar because can share traits that evolved in an ancestral population and are share due to genealogy and not removed iiAnimals subject to similar natural selection regimes in separate evolutionary histories c They may share traits that arose as mutations or adaptations i Neutral didn t effect likelihood of offspring in next generation tness 1Darwin observed this as well aVariations that are not affected by natural selection ii Neutral theory of the genome evolution 1Most of the genome didn t affect the tness of the organism aEvolving by stochastic processes genetic drift 2Kimura most changes in genome will not effect phenotype quotneutralquot 3Tells us of time in the deep history of life quotmolecular clockquot separate from rock dating d Molecular biology timeline i 1859 Charles Darwin Published On the Origin of Species ii 1985 P Sharp R Roberts Polymerase Chain Reaction 1Allowed to amplify DNA go from small DNA sample and produce many copies Breakthrough in molecular genetics 21987 Applied Bio systems rst sequencers aUnderies much contemporary biology iii All the separate contributions aided our understanding today e Molecular Clock over millions of years mutations may build up in any given stretch of DNA at a reliable rate i Al of the changes that occur in two lineages and comparing it to their most common ancestor 1How much different mutations occurred in the genome 2Not applied to DNA that is affected by natural selection only neutral characteristics in genome 2 Question What are largescale trends over long periods of time a Macroscope Diversity Across Time i All Life shares a single origin came from single species ii How has diversity increased over vast time b Macroscope ll how do we study innovation in shape and form new structures i Changes in shape and form ii Study fossils and living taxa to observe the sequence of change on a phylogeny 1Understand deep history and timing of change sequence 2Exampe Ear bones aCan view as a characteristic left by primitive ancestors or a recent development 3Example Dinosaur wings aSeries of steps in which a wing evolved iii Extremely complex examples 1Eyes has many engineering components aperture nerves lens aComplex light receptors bOctopus and scallop eyes relationship with human eye i First step Study structures in depth 1 Breaking down complex trait and observe its unfolding how natural selection could lead to the trait that is so complex ii Look at genetic similarities 1 Pax 6 is a quotmaster controlquot gene meta genes that controls suites of other genes a Similar gene and coding but 100 protein similarities b Due to a shared history 2 Evolution is descent with modi cation a Convergent origins but similar gene i History explains similarity but not in the phenotype eyes c Genes are homologous but many independent origins of complex eye structures from simple receptors i Tinkering there can be a limited number of ways that a structure can be organized functional constraint c Why do many solutions not look the same i Contingency or chance in separate and distinct evolutionary events 1Separate mutations and histories but natural selection for more nuance light sensing d Time small changes certain sequence on dial i Small changes over time lead to novelty in encoding citrate case in bacteria 1Tinkering a structure can have one function at its rst appearance but take on new functions aNew functions may be enabled through random or re ned events bMetaphors for the mode of change in shape and form i Engineering forward design and perfection of form emphasized ii Historical or phylogenetic constraint limited by what structures were inherited from ancestors what is available to quottinker withquot ii Caviomorph rodent in new vs old world and the quotrejiggeringquot of parts of ancestors to different ecologies 1Aspects of DNA phylogeny etc 2Capybara example l aResult of Natural Selection acting on whatever was at hand and in a completely separated environment South America bTinkering quote by Jacob i Evolution acts on existing variation that s why there s not one way that a certain characteristic can come to be in an organism 3 Stochastic Processes
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