3.Speciation.Post.2 - Bio - Nov.4

3.Speciation.Post.2 - Bio - Nov.4 - Speciation One species...

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1 Lajoie – Speciation ‘09 Speciation • One species becomes two or more species - Anagenesis - Cladogenesis • Most common source of diversity • Two concepts of species -Morphospec ies - Biological species Lajoie – Speciation ‘09 Morphospecies • based on physical features • Linnaeus - taxonomy, fossils • 1.5 million named species • 1 million extant species • Estimates range from 5 to 30 million undiscovered • More than 99% of all species are extinct But. .. much intraspecific variation - clines, races, ecotypes
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2 Lajoie – Speciation ‘09 Biological species • one or more populations • individuals interbreed in nature • produce fertile offspring • based on reproductive isolation • largest unit in which gene flow is possible • Usually morphospecies biological species Lajoie – Speciation ‘09 Biological species Problems: 1) asexual species ( Amoeba ) 2) fossils (temporal) 3) limited gene flow (semispecies)
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3 Lajoie – Speciation ‘09 Allopatric speciation –Stage1 Geographic barrier - rivers, mountains, climate, habitat - gene flow cut off between two populations e.g. - Kaibab squirrels in Grand Canyon - Pupfish in Death Valley - Warblers - 4 ice ages - Panama land bridge (+ and -) Geographic barrier Genetic divergence RIMs Lajoie – Speciation ‘09 Allopatric speciation –Stage2 Genetic divergence
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3.Speciation.Post.2 - Bio - Nov.4 - Speciation One species...

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