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BIOL 1002 General Biology Notes All

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Biological Sciences
BIOL 1002
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Acarcae Ch 22Monday January 14 20081013 AMCh 22Descent with Modification A Darwinian View of LifeThe theory of evolution is a valid scientific theory supported by evidenceWhat is Evolution and AdaptationoTwo main ideas of evolutionChange over time of the genetic composition of a populationDecent of modern organisms with modification from preexisting organismsAll organisms derived from a common ancestoroEvolutionary adaptationAccumulation of inherited characteristics that enhance organisms ability to survive in specific environmentsTraits that help organisms survive and reproduce that have an effect on the frequency of genes in future generationsEvolution in a Historical ContextoFigure 222oCatastrophism Gradualism and UniformitarianismCurviercatastrophismCatastrophes caused extinct species and formation of strata layers of sedimentary rock stacked up over long periods of timeMore biblical interpretation Noahs FloodWhere were fossils of species that are around todayHutton and Lyellgradualism and uniformitarianismSlow natural forces wind water earthquake volcanoes caused stratification and erosion of rock over timeObservations of geological formationrates processes occurEarth at least millions of years agooPreDarwinian Theory of EvolutionLemarckInheritance of acquired characteristicsBodies of living organisms are modified through the use or disuse of partsThese modifications are inherited by offspringoie Giraffes stretched necks to reach trees which gave them longer neck and legs over time and offspring gained long featuresThis idea turned out to be wrongoWhat you do in your lifetime wont necessarily influence offspringoMuscle builder wont necessarily have large muscles Jewish boys arent born without foreskin even though they have been circumcis2ed for centuriesEvolution by Natural SelectionoDarwin and Wallace developed the theory independentlyFirst credible account of how organisms change over timeoDarwinvoyage of the BeagleExtensive study of finches on Galapagos islandsExplained how organisms could change over timeoWallacenaturalist in IndonesiaWrote up natural selection ideas and sent them to DarwinBoth accounts were combined and presented Darwins Focus on AdaptationoDifferent environmental adaptationsInsect eaterslong slender beaksSeed eaterslarge curved beaksCactus eaterssmall pointed beaksoThought they were similar species that came from a common ancestoroAs they began to exploit different habitats they changed through time and evolved with different environmentDecent with ModificationoThey were likely birds from a single common ancestorTook on different ecological nichesTook on different anatomical form that made them more adapted to their environmentsoSimilar anatomical features of elephants in Africa and Asia because they descended from a common ancestorNatural SelectionoThe unequal survival and reproduction of organisms due to environmental forces resulting in the preservation of favorable adaptationOrganisms that have characteristics that help them to survive and reproduce pass along their genes to the future generation and have a disproportionate effect on the populationFavorable traits are passed on and have a larger impact on the population than unfavorable onesoProcess selects from what is available in the gene pooloNew characteristics are not created on demandIf traits do not occur through mutation or already exist they will not come in effectoMechanism behind Natural SelectionFigure on pg 444Organisms have the capacity for producing more offspring than can survive at one timeOnly small percentages of offspring surviveThe resources to support the organisms are finiteArent enough for all offspring to survivePopulation sizes are relatively constantstable over timeMust be competition for survival and reproduction with these selective pressuresCompetition and variable in structurebehavior cause natural selectionOnes with favorable traits fittest survive and those genetic traits are inherited by the next generation eventually changing the gene frequencies in a population causing evolutionoThink about the 100m dash track and field competition How can we change this race to reflect the process of natural selectionHurdlesLast one to the finish is outRun uphillTiger chasingReproductionwinners must be able to reproduceArtificial SelectionoSelective breeding of organisms to encourage the occurrence of desirable traitsHumans make the selection the agents of selectionLarger fruits high quality meatmilk livestockoAnalogous similar to natural selectionInstead of the fittest and most reproductive survive those humans select surviveoFigure 2210Darwins Theory Explains a Wide Variety of ObservationsoExamples of Natural SelectionReznick and Endley transplanted guppies into different ponds with different predatorsKillifish preyed on small guppiesGuppies larger at sexual maturity Pikecichlis preyed on large guppiesSmaller at sexual maturity Put guppies from Pikecichlis pond into the Killifish environment and saw that those guppies changed their maturity size became larger Selective pressure resulting in an observable evolutionary changeHIV ResistanceFigure 2213Brought about by use of drug to fight these infections3TCDrug that stops the reproduction of HIVoSome of the viral particles that are resistant to the drug and very quickly the selective pressure causes an influx of resistant HIVWithin a few weeks of treatment with the drug 3TC a patients HIV population consists entirely of 3TC resistant viruses How can this best be explainedoA few drug resistant viruses were present at the start of treatment and natural selection increased the frequency
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