evolution ppt edit - weebly · 2018. 9. 6. · darwin notes pt. 2 charles darwin – darwin was...
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The Theory of Evolution
Darwin
NotesPt.2
Charles Darwin
– Darwinwasbornin1809inEngland.
– HewasfromastrongChristianfamily.
– Age16,Darwinwassentbyhisfathertostudymedicine
– HeleftandenrolledatCambridgetobecomeaclergyman– Acareerthatallowedhimtopursuehisinterest inbecoming anaturalist
– Helovedscience&decidedtotakeseveralvoyagesaround theworldtostudy.– At22,hesetoutontheHMSBeagle
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Charles Darwin
– Proposedawayhowevolutionworks– Howdidcreatureschangeovertime?Bynaturalselection
– Collectedalotofevidence tosupporthisideas
Voyage of The H.M.S. Beagle
– 1831– 1836– Darwintookhisship,theH.M.SBeaglearoundtheworldtostudytherocks(geology),flora(plants)andfauna(animals)aroundtheworld.
– HeendedupintheGalapagosIslandsinthePacificOcean.
– Hesawmanystrangecreaturesandstudiedthemovermanyyears.
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Voyage of The H.M.S Beagle
– Stopped inGalapagosIslands– 500milesoffcoastofEcuador
Galapagos
– MostofanimalsontheGalápagoslivenowhereelseinworld,buttheylook likespecieslivingonSouthAmericanmainland.
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What Was Found?
–Darwinfound…manyuniquespecies– GiantGalapagosTortoise
– RedFootedBooby
– GalapagosIguana
– GalapagosFinches
–ManyofDarwin’sobservationsmadehimwonderwhy?
Giant Galapagos Tortoise
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What Was Found?
– Differentshellsontortoisesondifferentislands
– Darwinasked:– Istherearelationshipbetweentheenvironmentandwhatananimallookslike?
Red Footed Booby
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Galapagos Iguana
Galapagos Finches
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Darwin’s Finches
– Eachislandhadauniquespecies,eachwithadifferentbeaksizeandshape– Therewere14differentspeciesoffinches(birds) ontheGalapagosIslands,thatareuniquetothatarea.
– Darwinhypothesizedthatfinchesfromthemainlandcouldhaveevolved intoseparatespecieson theislandbynaturalselection
Darwin’s Finches
– Asthebirdswithsmallerbeaksdiedoff,thebirdswithlargerbeakscontinued toeatthefoodandmate/haveoffspring.
– The“largebeak”geneswerepassedontotheseoffspring,andeventuallyallthefincheshadlargebeaks,becausethe“smallbeak”genewaswipedoutofthepopulation.
– Thefincheshaveevolvedovermanygenerationstobettersurviveintheenvironment.
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Darwin’s Finches
– Darwin’sConclusions:– Variations inBeaks
– differencesinbeaksintheoriginalflock
– adaptationstofoodsavailableonislands
– NaturalSelection fortheMostFit
– overmanygenerations,thefincheswereselectedforspecificbeaks&behaviors
– OffspringInheritSuccessfulTraits– accumulationofwinningtraits:bothbeaks&behaviors
– SeparateintoDifferent Species
present day Armadillosancient Armadillo
More Evidence for Darwin
– DarwinfoundEvidenceinfossilsthatcreatureshavechangedovertime.
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Darwin’s View of Evolution
– Giraffesthatalreadyhavelongneckssurvivebetter
– Leavemoreoffspringwhoinherittheirlongnecks– Variation
– Selection&Survival
– Reproduction&Inheritanceofmorefittraits
Darwin Came Up With Two Main Points
1. DescentwithModification
2. NaturalSelection
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Darwin and Descent with Modification
–DarwinFound– Thedifferencesbetweenspeciesoffincheswereassociatedwiththedifferentfoodtheyate.
– Allfinchescamefromoneancestorbuteventuallyovertimenatureselectedfordifferentspecieswithdifferentbeaks.
Darwin and Natural Selection
“Survival of the Fittest”–NaturalSelection isalsoknownas“survivalofthefittest”.– Thismeansthatthestrongestofthespecies,theoneswiththebestnaturaldefenses,ortheoneswiththemostadvantageousvariations,willsurvive.
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Natural Selection Requirements
1. Variation- Individualsinapopulationhavedifferences
2. Heritability- Variationsareinheritedfromparents
3. Overproduction - Populationsproducemoreoffspringthancansurvive
4. ReproductiveAdvantage- Somevariationsalloworganismstohavemoreoffspringthanotherorganisms.
Natural Selection and Differential Survival
– Onlyalimitedamountoforganismsineachpopulationcansurvive.
– Sothetraitsthatareleftinthatpopulationcaneitherhelpthepopulationtosurvive&thrive&thereforeevolve,orharmit&causeittobecomeextinct.
– Whatmightlimitpopulationsize?– AccesstoFood– Predators– Sunlight– Space– Water
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Let’s Think…
–Canyouthinkofaphysicaltraitthatwouldgiveanorganismanadvantageinobtainingoneoftheselimitingfactors?– AccesstoFood
– Predators
– Sunlight
– Space
– Water
Variation In Moths
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What gives this moth an advantage?
Let’s Think…
–Whatwould happenifpollutionmadetreesdarker?
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Darker Moths Become More Common!
Is this Evolution?
– Yes,itisbecauseevolutionworksonpopulations
– Evolution:Achangeinapopulationovertime.