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Biodiversity

Biodiversity. Let’s start with… what is diversity?. Which community has the highest richness?. Which community has the highest diversity?. Why?. Most commonly used diversity measure:. Shannon-Weaver Diversity Index. aka. Shannon-Weiner Diversity Index. aka. Shannon Index.

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Biodiversity

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  1. Biodiversity

  2. Let’s start with…what is diversity?

  3. Which community has the highest richness? Which community has the highest diversity? Why?

  4. Most commonly used diversity measure: Shannon-Weaver Diversity Index aka Shannon-Weiner Diversity Index aka Shannon Index

  5. According to National Science Foundation Currently ~ 2 Million identified species Earth could contain from 8.7 ± 1.3 million Scientists estimate that up to 140,000 species are lost to extinction on a yearly basis; this current extinction rate is 100 to 1000 times the rate of species loss prior to human existence (Pimm et al. 1995). Figure from The Diversity of Life, EO Wilson, University of Harvard Press

  6. Rainforests: 6% of Earth’s surface- 50% of the species In the Amazon- - 170,000 species of plant (68% of the known total- 250,000) - In 5 acres- 300 species of tree. - 30% of all bird species http://www.exploratorium.edu/frogs/rainforest/index.html Pinning down exact numbers is nearly impossible, but most experts agree that we are losing upwards of 80,000 acres of tropical rainforest daily, and significantly degrading another 80,000 acres every day on top of that. Along with this loss and degradation, we are losing some 135 plant, animal and insect species every day—or some 50,000 species a year—as the forests fall.

  7. Coral Reefs the “rainforests of the ocean” • The Great Barrier Reef, the world's largest system of coral reefs, covers 349,000 square kilometers and occupying only one-tenth of one percent of the ocean surface, supports: • -nearly 8 percent (1,500) of the world's fish species, • more than 700 species of coral. • -over 4,000 species of mollusks. • -252 species of birds nest and breed on the coral cays, five species of turtles live on the reef, and several species of whales and dolphins are associated with it. • -Tropical (almost totally).

  8. Now, some theories of biodiversity…

  9. OK…so why are these two systems, the MOST diverse in the world?

  10. There is a latitudinal gradient in species diversity in marine & terrestrial systems. Includes many different genera and species! Hillebrand, H. 2004. On the generality of the latitudinal diversity gradient. The American Naturalist 163:192-211.

  11. More solar energy = greater species richness…but why?

  12. Hypotheses?

  13. Ecological filters dictate ultimate community composition

  14. Under what condition is diversity maximized? Species-Area Relationship http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

  15. Under what condition is diversity maximized? Two important hypotheses: Intermediate Disturbance Hypothesis Productivity-Diversity Hypothesis http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

  16. Intermediate Disturbance Hypothesis

  17. Intermediate Disturbance Hypothesis

  18. Under what condition is diversity maximized? Productivity-Diversity Hypothesis http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

  19. Diversity Productivity

  20. Question: Does diversity matter? http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

  21. General trends in the reproductive biology of rare plants. • Very often they produce few fruits, that have very minimal dispersal distances. • Are self-incompatible. • Have specific pollinator relationships that create vulnerability. (lose the pollinator, no more reproduction) • Are commonly pollen limited because there are not enough individuals around. • Seed set is uncommon and weak. • Some years, no seeds at all. Why are some species rare and others abundant?

  22. General trends in the reproductive biology of rare animals. • Not as clear general trends. • Mostly “K-selected species” • Bats for instance, have one or two babies a year max. Why are some species rare and others abundant?

  23. Biodiversity

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