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Historical Biogeography

Historical Biogeography. CH 7. Current Distribution. Result of the interaction of: Early history and place of origin Fragmentation of continents Climactic changes during Cenozoic Cooling and eventual ice age in Pleistocene Mass extinctions and adaptive radiations Land Bridges Bering

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Historical Biogeography

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  1. Historical Biogeography CH 7

  2. Current Distribution • Result of the interaction of: • Early history and place of origin • Fragmentation of continents • Climactic changes during Cenozoic • Cooling and eventual ice age in Pleistocene • Mass extinctions and adaptive radiations • Land Bridges • Bering • Greenland

  3. Deep Time Perspective • 4 Zoic Eras • Overview of Major Events • Historic Biogeography

  4. Table 25-1b

  5. The rise and fall of dominant groups reflect continental drift, mass extinctions, and adaptive radiations

  6. Continental Drift Present • At three points in time, the land masses of Earth have formed a supercontinent: 1.1 billion, 600 million, and 250 million years ago • Earth’s continents move slowly over the underlying hot mantle through the process of continental drift • Oceanic and continental plates can collide, separate, or slide past each other • Interactions between plates cause the formation of mountains and islands, and earthquakes Cenozoic Eurasia North America Africa 65.5 India South America Madagascar Australia Antarctica Laurasia 135 Mesozoic Gondwana Millions of years ago Pangaea 251 Paleozoic

  7. Mass Extinctions • The fossil record shows that most species that have ever lived are now extinct • At times, the rate of extinction has increased dramatically and caused a mass extinction • In each of the five mass extinction events, more than 50% of Earth’s species became extinct Dimetrodon Hallucigenia

  8. Fig. 25-14 800 20 700 600 15 500 Number of families: 400 Total extinction rate (families per million years): 10 300 200 5 100 0 0 Mesozoic Paleozoic Cenozoic Era Period E C Tr C O S D P J P N 200 145 65.5 0 542 488 444 416 359 299 251 Time (millions of years ago)

  9. Adaptive Radiations • Adaptive radiation is the evolution of many new species adapted from a common ancestor upon introduction to new environmental opportunities (new niches) • Occurs via: • Evolution of novelty (i.e., seeds) • After a mass extinction (i.e., mammals) • Formation of new land (i.g. islands) • Piggyback on other organisms (insect radiations follow flowering plants) BASICALLY, any time many new niches (ecological livelihoods) are available, there is opportunity for adaptive radiation.

  10. Table 25-1a

  11. Table 25-1a III. Multicellular Life - Neoproterozoic

  12. Table 25-1a

  13. V. First Life on Land VI. Conquest of Land Challenges: structural support dehydration reproduction Solutions: exoskeleton, lungs in animals what about plants? cuticle, stomata, vascular tissue, pollen – not all at once

  14. Table 25-1a

  15. Massive extinction – 250mya followed by adaptive radiation

  16. Table 25-1b Present • VIII. Emerging Modern Lineages • Triassic/Jurassic: • global warming, arid Pangaea interior, mountain formation • Reptiles loved it! Cenozoic Eurasia North America Africa 65.5 India South America Madagascar Australia Antarctica Laurasia 135 Mesozoic Gondwana Millions of years ago Pangaea 251 Paleozoic

  17. Table 25-1b Present Cenozoic Eurasia North America Africa 65.5 India South America Madagascar Australia Antarctica Laurasia 135 Extinction Mesozoic Gondwana Millions of years ago Pangaea 251 Paleozoic

  18. Fig. 25-17 Ancestral mammal Monotremes (5 species) ANCESTRAL CYNODONT Marsupials (324 species) Eutherians (placental mammals; 5,010 species) 50 200 250 100 150 0 Millions of years ago

  19. Present Mountain ranges: Himalayans , Rockies (Eocene), Sierra Nevada (Miocene), Cascades, Coast ranges (late Miocene) Cenozoic Eurasia North America Africa 65.5 India South America Madagascar Australia Antarctica Laurasia 135 Mesozoic Gondwana Millions of years ago Pangaea 251 Paleozoic

  20. Great American Interchange Panama Isthmus formed 3 mya • Panama bridge • 26 genera S • 12 went N • Tapirs/llamas went extinct in N Am, so disjunct w/Asian

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