THE ROOTS OF CURRENT DISTRIBUTIONS:
explanations from the fossil record

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    CENOZOIC "the age of mammals"


      Mesozoic Isolation
      • Australian 91% endemic
      Cenozoic Isolation
      • African 36% endemic
      • Neotropical 47% endemic
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    PLEISTOCENE climate


  • Nearctic and Palaearctic Diversity
  • African Grasslands - Savannahs
  • African and Neotropical Frugivory
  • Australian megacarnivores
    • Low herbivore population
    • Reptiles starve more gracefully
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    MESOZOIC


  • Angiosperms originated in Jurassic
    • Broader distributions
    • Spread Northward
  • Plant speciation, survival, and distribution
    • Neogene invasion of Compositae, Gramineae, Leguminosae, Chenopodiaceae
    • Plant taxonomy ≠ Animal taxonomy
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    Antarctic Province


  • Oligocene Glaciation

  • Cenozoic next






    Mammalian Biotic Provinces


    • Neotropical and African maximum diversity
    • Nearctic - Palearctic similarity tracks
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    Flowering Plant Biotic Provinces


    • Neotropical and African maximum diversity
    • Gondwanan similarity tracks
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    Malasian archipelago

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    • Lydekker - Australia only
    • Wallace - birds
    • Weber - Mammals & mollusks
    • Murray, Muller, Sclater, Mayr
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    • New Guinea insect faunas limited to terranes
      • didn't move after the collision
      • different soils
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    • New Zealand angiosperms
      • Isolated since Cretaceous
      • Flooded during Paleogene
      • Uplift
      • Pleistocene glaciation
    • Moa Kiwi Sphenodon
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    • New Zealand angiosperms
      • 85% endemic species
      • 10% endemic genera
      • 0 endemic families
    • Moa Kiwi Sphenodon
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    South America

    • Cretaceous island filter
      • some dinosaurs
      • primitive mammals
    • Paleogene Atlantic Filter?
      • New World Monkeys
      • Cavimorph rodents
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    South America

    • Neogene collision of N & S America
    • Pliocene Uplift of Andes
      • Development of Pampas steppe and Desert
    • Pleistocene
      • Arid Floras displaced poleward
      • South American vegetation fills Tropics
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Holarctic

    Paleogene
    • Warm broadleaved flora interchange
    • Mammalian Faunas - later spread southward
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Holarctic

  • Asian interchange - lowered sea level
  • Neogene cooling
    • closed Bering LB to tropical taxa
      • prevented Apes from entering New World
    • 90% extinction of European Flora
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CENTERS OF ORIGIN

  1. which regions are cradles of evolution
  2. how have biotas (provinces) assembled
  3. thirteen criteria of Cain (1944)
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Example of "Centers of Origin"

sea snakes Hydrophiidae (50 sp.)
  • Traceable
    • Restricted by temperature 20 oC
    • Cenozoic origin
    • Distributions overlap with nearest relatives (Elapidae, cobras)
    • Intermediate forms trace speciation
  • Australian-New Guinea origin
    • Highest diversity (30 sp.)
    • Location of closest relatives
    • Most primitive genus in New Guinea
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Issues of Centers of origin

  1. basic assumption is the 13 criteria
      unproven scenarios
  2. tropical vs. arctic origins
      both have been assumed to be centers
  3. "unproven just-so stories" without verification
Vavilov's Cultivate Plant Centers next