PLEISTOCENE BIOGEOGRAPHY

Geological Time Scale Cenozoic Climate History and Biome Distributions

• polar land mass [.]
• no circum-equatorial ocean circulation [.]
  

Glacial Record

Extent of Ice

Continental Ice Sheets

http://geochange.er.usgs.gov/pub/sea_level/Core/raw/quaternary/images/gif/ice_age.gif
• Laurentide
• Cordilleran
• Scandinavian
• Siberian

Climate Change

Ganopolski, A., Rahmstorf, S., Petoukhov, V., and Claussen, M. 1998. Simulation of modern and glacial climates with a coupled global model of intermediate complexity Nature 391: 351-356.

Effects of Glacial Climate on Nonglaciated Areas

• Seasonal Temperature [CLIMAP]
• Jet Stream [COHMAP]
• Sea Level Changes
  • Isostatic: depression of crust, flexure
  • Eustatic Sea Level Cycles
    

Causes of Glaciation

• Eccentricity 100 Ka
• Tilt 40 Ka
• Precession 20 Ka

Feedbacks for Orbital Forcing

NASA April 7-22, 2002
• Albedo snow and ice vs. vegetation
• Oceanic Thermohaline Circulation [NADW]
• Atmosphere [CO₂]
• Ice Sheet Instability [Isostacy]
• Other [COHMAP]

Impact of Glacial Climate on Biomes


EUROPE: Spain - Norway

Glacial Vegetation of Arizona

Glacial Vegetation of the West

Biogeographic Responses to Glaciation

• Full-Glacial Map -
• Vegetation Migrations
  • Mammals [+]
  • Vegetation [Davis] [Delcourt]
• Vegetation Dynamics of the Southwest
  • Elevation
    [Pleistocene] [pollen] [packrat middens (Cole)]

Biogeographic Responses to Glaciation of Aquatic Ecosystems


Lake Agassiz .
• Pleistocene Catastrophic Floods [Scabland]
Pluvial Lakes [GSL map] [GSL Levels] [+ map]
• Mediterranean Climate Pluvials
• Monsoonal Climate Pluvials

Pleistocene Cycles and Biotic Exchange

Habitat Connections

Southwest - Argentina Disjuncts [Larrea]

Pleistocene Cycles and Biotic Patterns

• Canada - Western USA [Fernald]
• Driftless Area (Wisconsin) USGS fig

Pleistocene Cycles and Biotic Speciation

• Small Population Size fluctuations
  influence of random mutations
  rapid speciation
  
• Barriers (allopatric speciation)
  Drainage Changes / Forest vegetation corridors
• Episodic reunion of separated taxa
  Reticulate Evolution: hybridization
• Refugia centers of speciation
  Amazon [Haffer]

Pleistocene Megafauna Extinctions

• Ice Free Corridor -
• Coastal Route -)
• Solutrean Seamen -
• Overkill and Blitzkrieg [Martin 1973] [Megafauna]

Island Extinctions

• Dodo † 1600
• Dave Steadman (birds) Cook & Tonga Isl. Hawaiian Isl.
• Survival Wrengel Island Mammoths