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Why Study Paleoecology?

Why Study Paleoecology?. -- how and why communities change. -- causes of extinctions, development of modern communities. -- predict future changes. https://en.wikipedia.org/wiki/California_condor#. California Condor. California Condor once nested in Grand Canyon caves.

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Why Study Paleoecology?

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  1. Why Study Paleoecology? -- how and why communities change -- causes of extinctions, development of modern communities -- predict future changes

  2. https://en.wikipedia.org/wiki/California_condor# California Condor

  3. California Condor once nested in Grand Canyon caves

  4. Fossil remains mummify and preserve quite well in dry caves

  5. California Condor once nested in Grand Canyon caves

  6. Gymnogyps californianus (California Condor)

  7. Condors have been successfully reintroduced to Grand Canyon, nesting again for first time in 10,000 yrs

  8. Problems with fossil record -- Preservation varies soft parts usually don’t preserve exceptions in ice, bogs, amber -- Mode of deposition important stream deposits accumulate fossils caves preserve cave-dwelling species natural traps -- Behavior of species important caves and natural traps again

  9. Taphonomy: -- understanding the history of deposition Uniformitarianism: -- physical processes of today (weathering, stream flow, erosion) are the same as in the past

  10. Giant Armadillo

  11. Fossil Assemblages can be: -- Biocoenose: represent a true community from the past -- Thanatocoenose: not a true community, but an assembly of species associated only in death, or only in fossil deposit What would be the ideal fossil site?

  12. Bushy-tailed Woodrat

  13. woodrat midden

  14. The Last Glacial Maximum (LGM) at ~18,000 B.P. jan.ucc.nau.edu

  15. Changes in pinyon tree distribution since the Ice Ages

  16. Disharmonius or Non-analog Faunas

  17. Mixed or non-analog plant and animal communities characterize the late Pleistocene in North America Species assemblages with no modern analogy, usually composed of taxa that occur in warm and cold climates that are not found together today e.g., lemmings in cave faunas in the western U.S. along with desert rodents, or snowy and hawk owls with vultures and sage grouse This pattern was probably due to mild winters and cool summers that characterized post-LGM climates

  18. Loss of megafauna and keystone species would have had a dramatic impact on plant and small mammal communities www.news.wisc.edu By the end of the Pleistocene at 10,000 B.P., over 30 genera of large mammals became extinct Small mammals (< 5 kg), however, suffered few or no extinctions Modern communities were well established by 6000 B.P.

  19. Rancho la Brea Tar Pits, CA George C. Page Museum

  20. Dire Wolf skulls

  21. Paleobiology of Sabretooth cat based on functional morphology

  22. What happened 10,000 years ago? -- mass extinctions worldwide -- targeted mainly large mammals -- 33 genera of ‘megafauna’ disappear -- marine life, plants largely unaffected Pleistocene Overkill Hypothesis -- proposed by Paul Martin in 1960s -- extinctions correlated with human population expansion -- hunted large mammals, arrived in NA at ~12,500 years ago -- testable, controversial hypothesis that is still valid

  23. Quiz • What are three things we can learn about modern communities from paleoecological studies? • What biases can occur in the fossil record that can affect interpretations? • What is a biocoenose vs thanatocoenos and why is it important to know this about a fossil site? • What are packrat middens and how do they give us a more complete picture about past communities? • What is the Pleistocene Overkill Hypothesis and evidence to support it?

  24. Names to know for final exam: know their major contributions to ecology, significance of their work. Robert MacArthur Charles Krebs Paul Erhlich Jane Lubchenco Joseph Connell G. F. Gause Margaret Davis Paul Martin C. H. Merriam

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