ROBERTS Download 15

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Download 15 Speciation,Classification ,Extinction Principles of Biology BIOL 1543 Greig Roberts, DDS Office: SCEN 417 E-Mail: [email protected]
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2 The Origin of Species This  c hapte r links  “m ic ro e vo lutio n” with “m ac ro e vo lutio n.” Microevolution  = C hang e s  in a po pulatio n’s  g e ne  po o l o ve r  a s uc c e s s io n o f a fe w g e ne ratio ns  w/o  c hang ing  s pe c ie s . “Mesoevolution”  is a term that could mean development of a new species – speciation . Macroevolution  = e vo lutio nary c hang e  o n a g rand s c ale   inc luding  m as s  e xtinc tio ns .
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3 What is a species? Carolus Linnaeus, a Swedish physician and botanist, u sed physical characteristics to distinguish species. He developed the binomial system ( Genus species ) that established the basis for taxonomy , the branch of biology concerned with naming and classifying the diverse forms of life. Domain Order Kingdom Family Phylum Genus Class species Similarities between some species and variations within a species can make defining a species difficult.
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4 The Biological Species Concept The biological species concept defines a species as a population or group of populations whose members can interbreed and produce fertile offspring. Other Species Concepts Morphological species concept Ecological species concept Phylogenetic species concept Species Definitions
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5 Table 14.3 Reproductive barriers keep species separate Reproductive barriers s erve to isolate a species’ gene pool and prevent interbreeding. They are categorized as prezygotic or postzygotic . Maintaining Species
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6 Prezygotic Barriers Prezygotic barriers prevent mating or fertilization between species. They include: temporal isolation - timing is different behavioral isolation - no sexual attraction mechanical isolation - physically doesn’t work Maintaining Species
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7 Postzygotic Barriers Postzygotic barriers operate after hybrid zygotes are formed. These include: hybrid inviability hybrid sterility hybrid breakdown
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8 MECHANISMS OF SPECIATION Geographic isolation can lead to speciation In allopatric speciation , a population is geographically divided, and new species often evolve. Bentonville Springdale Fayetteville
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9 MECHANISMS OF SPECIATION Geographic isolation can lead to speciation In allopatric speciation , a population is geographically divided, and new species often evolve.
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