L20 historical biogeography

L20 historical biogeography - BILD 3 July 23, 2010 Biomes...

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BILD 3 July 23, 2010 Woodruff: historical biogeography 1 Biomes are very useful in defining ecologically similar communities over large areas. Biogeographic regions or realms capture systematic and historical associations of faunas (zoogeography) and floras (phytogeography) Alfred Russel Wallace is regarded as the “Father” of zoogeography; divided the world into six regions based primarily on terrestrial mammal & bird distributions in 1876 Holarctic = Palearctic + Nearctic “Old World Tropics” = Ethiopian + Oriental Neotropics Australian HISTORICAL BIOGEOGRAPHY Q. Is the present the key to the past? Principle of uniformitarianism, Charles Lyell 1830 Gradual changes by processes observable today A. This was a breakthrough in 1830 but not always… The planet is inconveniently dynamic… everything physical moves, everything changes populations and species change: evolve species coevolve and their interactions change LE 50-5 Tropic of Cancer (23.5°N) Equator (23.5°S) Tropic of Capricorn Neotropical Ethiopian Australian Oriental Nearctic Palearctic ZOOGEOGRAPHIC REGIONS OR REALMS Holarctic = Palearctic + Nearctic LE 50-5 Tropic of Cancer (23.5°N) Equator (23.5°S) Tropic of Capricorn Neotropical Ethiopian Australian Oriental Nearctic Palearctic OWT Old World Tropics as the well-spring of evolution with dispersal to the southern ends of the earth GLOBAL PATTERNS: OLD INTERPRETATION… LE 26-18 North American Plate Eurasian Plate Philippine Plate Indian Plate Arabian Plate Australian Plate Antarctic Plate African Plate Scotia Plate South American Plate Nazca Plate Pacific Plate Cocos Plate Juan de Fuca Plate Caribbean Plate NEW INTERPRETATION BASED ON PALEOGEOGRAPHY Plates shift new crust is produced at the rifts. Mountains as collision products. 16 x 100 km-thick plates currently. LE 26-20 By about 10 mil ion years ago, Earth’s youngest major mountain range, the Himalayas, formed as a result of India’s col ision with Eurasia during the Cenozoic. The continents continue to drift today. By the end of the Mesozoic, Laurasia and Gondwana separated into the present-day continents. By the mid-Mesozoic Pangaea split into northern (Laurasia) and southern (Gondwana) landmasses. At the end of the Paleozoic, al of Earth’s landmasses were joined in the supercontinent Pangaea. 0 65.5 135 251 Milions of years ago Cenozoic Mesozoic Paleozoic North America Eurasia Africa India South America Madagascar Australia Antarctica Laurasia Gondwana Pangaea PLATE TECTONICS AND CONTINENTAL DRIFT (Wegener) Laurasia Gondwana Break-up of Pangaea 200 Mya
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BILD 3 July 23, 2010 Woodruff: historical biogeography 2 Sea floor spreading documents continental “drift” of up to 6 cm/yr Slab pull into subduction zones provides most of the force Paleolatitude and
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L20 historical biogeography - BILD 3 July 23, 2010 Biomes...

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