Amphibian Biogeography

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Amphibian Biogeography
2011-10-30 02:13:22

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  1. Early Triassic (200 mya)
    • Land masses were joined as Pangaea
    • Tropical region at the equator
    • Temperate regions at the upper and lower latitudes
    • Tropical and Temperate regions seperated by arid zones/regions
    • Kolyma Block breaks off to eventually collide with Asia in the Cretaceous
  2. Early Jurassic
    • Laurasia (N.A, Europe, and Asia) and Gondwanaland (S.A, Australia, Antartica, India, and Africa) split apart
    • Opens up the Atlantic Ocean
    • Climate changed (tropics expanded and arid belts contricted)
  3. Late Jurassic
    • Gondwanaland splits into 3 land masses:
    • South America and Africa
    • Antartica and Australia
    • India
  4. Cretaceous
    • Mid-continental saline sea divided N.A. into east and west
    • Europe and Asia split
    • Africa and S.A. split apart
    • Europe and N.A. split apart
    • Madagascar near it's present position
    • India is moving northward
    • Kolyma block collides with Asia
    • Most of the world has a tropical climate
  5. Cenozoic (The past 65 my)
    • India collides with Asia forming Himalayas- an effective barrier between the two areas
    • Australia splits from Antartica and drifts east
    • S.A drifts west and joins N.A via C.A (only 3-6 my)
    • General cooling to the climates we have now
  6. Things to consider
    • Amphibians are tied to water so they could not cross arid regions
    • Couldn't cross oceans or mid-continental seas (some rafting)
    • Temperature is a barrier in some mountain regions and the poles
  7. Caecilian Biogeography
    • 6 families all in tropical regions
    • S.A., C.A, Africa, India, and S.E Asia
    • Present on Gondwanaland before it split apart (explains why they are located in S.A. and Africa)
    • India broke off Gondwanaland and took them to S.E. Asia
    • Simply expanded their range from S.A. to C.A. once they joined together
  8. Salamander Biogeography
    • 10 living families and all fossils are associated with Laurasia (Europe, N.A., and Asia)
    • None found in Old World tropics (Africa)
    • Fossils found from the Jurassic
    • Plethodontids have recently radiated to C.A. and S.A.
  9. Name the three salamander families located in N.A. and Europe
    • Plethodontidae (also in C. and S. America)
    • Proteidae
    • Salamandridae (also Asia)
  10. Name the five salamander families only in North America
    • Sirenidae
    • Amphiumidae
    • Dicamptodontidae (western N.A)
    • Rhyacotritonidae (western N.A, rapid streams)
    • Ambystomatidae (E. and W. North America and down into Mexico)
  11. Cryptobranchidae
    • Was once limited to N.A.
    • Kolyma Block breaks off and take some with it
    • Kolyma Block collides with Asia in the Cretaceous
    • Cryptobranchus in N.A (east and middle) and Andrias (Japan and China)
    • Cryptobranchidae in Asia gave rise to the family Hynobiidae
  12. Anurans
    • Nearly 30 living anuran families
    • Oldest fossils from Jurassic, but were widespread over Pangaea in Triassic before split
  13. Leiopelmatidae
    • Ascaphus and Leiopelma in that family
    • Family spread prior to the split
  14. Ascaphus
    found in NWNA
  15. Leiopelma
    Found in New Zealand
  16. Conventional wisdon used to be that frogs began and radiated from Gondwanaland, but looking more closely there are several families whose members and fossils are only found in northern areas associated with Laurasia
  17. What anuran species were only found in northern areas associated with Laurasia?
    • Family- Discoglossidae (Alytes obstetricans = mid-wife toad)
    • Family- Pelobatidae (Scaphiophus holbrooki = spadefoot toad)
  18. Bufonidae
    • Have affinity with Gondwanaland
    • One of the most successful amphibian families (25 genera and 300 species)
    • Not found in Australia (so it did not radiate southward in time or was out-competed by other groups)
  19. Ranidae
    • Have affinity with Gondwanaland
    • Also very successful (40 genera and 600 species)
    • Found in all continents, except Australia, the poles, and southern South America
    • Originated in Africa and radiated (greates diversity in tropical Africa)
  20. Hylidae
    • Have affinity with Gondwanaland
    • 3rd successful family
    • Found in all continents, but Africa and the poles
    • Hylidae sprang from Microhylidae before S.A. and Africa split (made it to Australia)
    • Absent from Africa due to competition with Hyperoliidae (another treefrog family, but only found in Africa)