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Species Diversity

Species Diversity. Chapter 16 and parts of Chapter 22. Textbook Readings for 4 th edition. Chapter 16: Pp. 404-412 (small scale explanations) Chapter 22: pp. 546-556 (large scale explanations). Intermediate Disturbance Hypothesis (IDH)—chapter 16. Connell: Rainforests and Reefs

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Species Diversity

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  1. Species Diversity Chapter 16 and parts of Chapter 22

  2. Textbook Readings for 4th edition • Chapter 16: Pp. 404-412 (small scale explanations) • Chapter 22: pp. 546-556 (large scale explanations)

  3. Intermediate Disturbance Hypothesis (IDH)—chapter 16 • Connell: Rainforests and Reefs • Does it apply elsewhere in real life (not just a model, but observation)?

  4. Experimental evidence of IDH

  5. Prairie dogs

  6. Next Monday, November 16th • Students for Environmental Awareness (SEA) meeting: 5:30 p.m. in Lewis Hall 131 (new classroom)

  7. What about Global Patterns? • Chapter 22 (mostly)

  8. Plant species diversity vs. latitude

  9. There are exceptions, however

  10. Salamanders also reach diversity in temperate forests

  11. Biodiversity Hotspots • “Hotspots” • High Diversity • High Threat by humans • Need for preservation

  12. Diversity of Species: Latitudinal Changes Pines and Oaks Birds Butterflies

  13. Vascular Plant Diversity

  14. All of this assumes the following: Speciation in tropics >>> Extinction in tropics Species in tropics speciation extinction Species in temperate zone speciation extinction Speciation in temperate Zone > extinction in Temperate zone

  15. Why? Hypotheses 1) Time Since Pertubation • More time for speciation • Less frequent perturbation reduces extinction

  16. Hypothesis #2 • Productivity • More energy=more biomass=more diversity • For example, coral reefs and rainforests

  17. From Chapter 16

  18. Rank-Abundance changes due to fertilization From Chapter 16

  19. Hypothesis #3: Environmental Heterogeneity • More heterogenous environments make more diversity • Species in more diverse environments subdivide habitats more finely • E.g. birds in Panama and the Caribbean birds will restrict habitat use if there’s more species present, which brings us to…

  20. The Tropics: The Riches of Niches • Biological interactions are dominant in tropics; physical interactions are dominant in high latitudes • Interactions include things like competition, predation, parasitism and mutualisms • Competition is more interspecific (between species) than intraspecific (within a species) in the tropics

  21. Niche Possibilities • Narrower niches in the tropics i.e. more specialization • More niche overlap in tropics

  22. Maybe it’s a complex set of reasons why tropics are more diverse… • Large scale: A climate driving less extinction and more speciation combined with • Smaller scale processes such as disturbance leads to • More niches available for species to occupy and therefore more species… • And more niches can make more niches!!!

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