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Ch 1 - Introduction to Evolution.docx

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PSYC 208
Paul Wehr

Introduction to Evolution 07092012 95600 AM IntroductionMisconceptions Species do not outcompete other species individuals outcompete other individualsEvolution change over time in organic structure or behaviour change in gene frequencyEvidence of EvolutionStructural similarities among species ex mammals have same basic body plantFossil records are evidences of evolutionEmbryological development Embryos of many species look similar until later developmentDNA Basic building blocks of DNA are identical thymine cytosine guanine adenine suggests common ancestors Evolution by natural selection need to explain the followingSpecies are createdSpecies go extinctSpecies are welladapted to the environmentSpecies share similaritiesCharles DarwinNaturalist on The Beagle 18311836led to theory of evolution by natural selection published inOrigins of Species 1859Delayed publication because of religious pressure Did not apply to human beingsThe Descent of Man 1874Applied theory of evolution to human beingsAlfred Russell WallaceCodiscoverer of evolution by natural selectionOfficially recanted his theory pressure from the church other scientistsNaturalistThomas Henry HuxleyRead Darwins theory became Darwins bulldog aggressively defended Darwins theoryConvinced after Origin of Species Darwinian EvolutionGood theory explain a lot using very littlePrinciples of EvolutionVariation individual differences between members in a species height eye colorInheritance heritable traits are passed along generations inherited characteristicso Traits passed on from parents to offspring o Acquired traits dont get passed on eg hair dye traits you acquire throughout lifetimeSelection some entity is selecting individuals to reproduce more or less than others o Fact Organisms exist in larger numbers than their environment can sustain o Because of this fact not everyone will reproduce Artificial Selection Selection comes from humans which organisms willwill not reproduce based on preferred characteristicsExplains domestication of plants and animals wolfcute little Pitbull German Shepherd and mustard plantbroccoli cauliflower brussel sproutsDomestication of dog breeds designer dogsNatural SelectionSelection comes from environment o Selection pressures do the selection eg diseaseExplains speciation extinction adaptation o Speciation creation of new species from old species o Extinction the complete extinction of an species o Adaptation how organisms change to adapt to its local environmentSelection TypesStabilizing SelectionPositive selection favouring middle of distribution selecting out outliers distribution narrows and amplitude increasesEx Risktaking behaviours highend is taking unnecessary high risks middle reproduces the most theres an optimal level of risktakingindividuals do well too muchlittlebadVariability will decreaseSee it in a stable environment that doesnt change over timepredictable changeDirectional SelectionSelection favours one side of distribution distribution shifts to one directionIndividuals high or low will reproduce mostEx brain size big brained people produce offspring whole population shifts towards large brainsOccurs when environment changesDisruptive SelectionSelection for the extreme high or extreme lowproduces mediocre offspringEx Predation large individuals are too hard to prey small individuals are too sneakyaveragesized individuals are selected outCreates two separate distributions which move further and further from each otherOccurs when environment changesSexual SelectionEvolution alone cannot explain why females and males are biologically differentSelection comes from own speciesFor humans selection comes from humans for dogs it comes from dogsIntrasexual selection members of one sex compete to mate with members of opposite sex o Usually males compete eg deer with huge antlersIntersexual selection members of one sex choose members of opposite sex based on preferred characteristics o Usually females choose o Eg peahens choosing peacocks based on immune system feathersExplains sexual dimorphism biological differences aid members of the species in competing o Two different body types for sexes The only thing males contribute in regards of reproduction is genes therefore females need to gain the best genes possibleHuman EvolutionMammals 200 myaWarmblooded mammary glands females produce milk internal fertilization fertilization of egg occurs inside femalegustation safer to develop inside female placentaPrimates 85 myaNails instead of claws opposable digits thumbs stereoscopic vision tailored for predators encephalization bigbrained two mammary glands small number of births per pregnancyBipedal locomotion 44 myacharacteristic of hominid Travel long distance bipeds can travel further greater visual angle carry objects sun exposureStone tools 2myastone flakingtwo rocks bang them together one leaves a sharp edge use it for cuttingEncephalization 12 mya1350 cc cerebrumcerebellumbasal gangliaBelding Ground Squirrels
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