THE ROOTS OF CURRENT DISTRIBUTIONS:
explanations from the fossil record

CENOZOIC "the age of mammals"


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

PLEISTOCENE climate



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

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

Antarctic Province



• Oligocene Glaciation
  
  
• Cenozoic
  • Australian Diversification
  • New Caldonia
  

Mammalian Biotic Provinces



• Neotropical and African maximum diversity
• Nearctic - Palearctic similarity tracks

Flowering Plant Biotic Provinces



• Neotropical and African maximum diversity
• Gondwanan similarity tracks

Local Histories



• Madagascar
  • High Endemism - filter / sweepstakes
  • Endemic Carnivores - sweepstakes
    A.D. Yoder J.J. Flynn, et al. 2003. Single origin of Malagasy Carnivora from an African ancestor. Nature 421: 734 - 737. whyfiles.org/shorties/124madagascar/ +
• Cape Flora
  • Mediterranean Climate Endemism

Australia

• Antiquity (200 Ma)
• Northward drift into doldrums
• Tectonic wasteland.
  • Very poor soils
  • New Guinea (northern Australian plate) collision

Malasian archipelago

• Floristically one region
• Faunally Oriental-Australian (Wallace) filter
  

Malasian archipelago


• Lydekker - Australia only
• Wallace - birds
• Weber - Mammals & mollusks
• Murray, Muller, Sclater, Mayr

• New Guinea insect faunas limited to terranes
  • didn't move after the collision
  • different soils

• New Zealand angiosperms
  • Isolated since Cretaceous
  • Flooded during Paleogene
  • Uplift
  • Pleistocene glaciation
• Moa Kiwi Sphenodon

• New Zealand angiosperms
  • 85% endemic species
  • 10% endemic genera
  • 0 endemic families
• Moa Kiwi Sphenodon

South America


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

South America


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

Holarctic

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

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

CENTERS OF ORIGIN

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

Example of "Centers of Origin"

• 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

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