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12 Cards in this Set
- Front
- Back
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How did climate change relate to biogeographic ranges during Quaternary?
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○ Expansion and Contraction of Geographic Ranges
§ Latitudinal and elevational shifts ○ Fragmentation of geographic ranges § Geographic relicts ○ Magnitude and frequency of change § Always trying to adjust to environmental changes § Red light green light analogy |
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Global Glaciation during Pleistocene--extent and time period
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(at maximum extent) about 30% of surface was covered in ice
○ Pleistocene Epoch § Most recent global ice age § Beginning 2.58-1-8 mya (about 2 mya) § Ending 12 kya to 8kya |
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Global glaciation during Holocene--extent and time period
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§ Interglacial
§ About 10 kya to present § Laurentide Ice Sheet □ Extended into KA, NB, etc □ Maximum depth was apx 3000 m. § Major glacial advances like: Wisconsin, Illinoisan, Kansan, Nebraskan, and elk creek glaciation periods |
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Hypsothermal
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§ The hypsothermal was the highest temperature in the last 10 thousand yrs.
□ This is the period of oak expansion |
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Sea Level Change extent during climate change periods
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○ During glacial periods the sea level dropped 100 to 160 meters lower than present
○ During interglacial periods the sea level was about 70 meters higher than present |
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• Isostatic Rebound--Definition and example
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is the rise of land masses that were depressed by the huge weight of ice sheets during the last ice age
○ Hudson Bay has risen 250 m § Great lakes drainage into Mississippi river instead of hudson Bay ○ Scandanavia 1 meter per year |
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§ "Where did the organisms displaced by glaciers go?"
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□ Historical explanation is that they headed south by 10-20 degrees southward
□ Also takes static perspective of zones and states that biomes maintained their relative locations, but that there were longitudinal corridors that facilitated migration |
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"How did biotas reestablish themselves? Zonal shifts or dispersal?"
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□ This question is hard to address because there is a lack of modern analogs (i.e. the communities of yesterday are not the same of today)
□ Pollen evidence suggests that there are relict and current populations suggest that communities were not static □ There was a lot of mixing between communities □ This relates to Gleason's central theories □ Current relict and ishunct disributions and pollen data do not support latitudinal shifts of communities □ There is a possibility of "refusia" where there are breaks (nunataks) in the ice sheet that allows plant growth ® These areas are found at very high altitudes where and polar areas |
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Paul Martin: Proposal and Points
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humans are responsible to the great die-off of mega fauna
○ His points include § Humans were skilled and aggressive hunters § Human population growth § Animals that have never encountered humans do not have avoidance predispositions. They are "naive" |
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Paul Martin Supporting evidence includes
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§ Paleo-indian kill sites
§ Non-random extinction of large mammals § North to south geography of extinctions § In Australia 85% of extinctions occurred to animals that were over 44 Kg. |
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Counter evidence to paul martin
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§ Also birds suffered high rate of extinction
§ Other high rates of extinction have been attributed to climate change □ Eg Blancan extintion that happened 3mya resulted in extinction of 125 mammal species § Climate change related to range compression § Low reproductive rate of large mammals § Introduction of new diseases |
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2 theories related to Paul Martin's
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○ Related theory #1
§ Lewis and Clark noted huge large mammal populations in N.America □ Low hunting pressure in war zones result in abundant game within zone ○ Related theory #2 § Large mammal populations experienced ecological release during period of exploration and westward expansion of Euroamericans □ Low native American populations caused by high disease-induced mortality |
