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Lecture 13

BIOL 1F90 Lecture Notes - Lecture 13: Macroevolution


Department
Biological Sciences
Course Code
BIOL 1F90
Professor
Fiona Hunter
Lecture
13

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BIOL1F90
Feb.1st,2016
Chapter23OriginofSpecies
EtymologyofKeyTerms
Inter:between,among
Macro:large,canbeseenwithnakedeye
Phylo:tribe,race,phylum
Post:behind,intherear
Pre:earlierthan
Zygote:diploidcellcreatedbyfertilization
Species:Agroupoforganismsthatmaintainsadistinctivesetofattributesinnature
Macroevolution
Evolutionarychangesthatcreatenewspecies(andgroupsofspecies)
Occursbyaccumulationofnumerousmicroevolutionarychanges(changesinsingle
genes)
Macroevolutionhasbeendescribedas“microevolutionwritlarge”
Knownnumberofspeciesabout1.41.6million
Estiamtedofunidentifiedspeciesrangefrom2100million
Difficultyinidentifyinga‘species’
asinglespeciesmayexistin2distinctpopulationsthatareintheslowprocessesof
evolvinginto2ormoredifferentspecies
Amountofseparationtimefor2populations
Shorttime–likelytobesimilarandconsideredthesamespecies
Longtime–morelikelytoshowunequivocaldifferences
Mayfindsituationswheresomedifferencesareapparentbutdifficulttodecideifthe2
populationsaretrulydifferentspecies
Sometimesusesubspeciesclassification
BiologicalSpeciesConcept
Aspeciesisagroupofindividualswhosemembershavethepotentialtointerbreedwithone
anotherinnaturetoproduceviable,fertileoffspringbutcannotsuccessfullyinterbreedwith
membersofotherspecies
Reproductiveisolationpreventsbreedingwithotherspecies
Threepotentialproblems
Maybedifficulttodetermineif2populationsaretrulyreproductivelyisolated(unless
transplantationexperimentsconducted…buteventhentheremaybeproblems)
Therearecaseswhere2speciescaninterbreedbutgenerallydonotmatewithone
another
Cannotbeappliedtoasexualspecies
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