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Download keystone species are predators Regulation of community structure…
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Predator Prey Relationships Predator Prey Relationships • Specialist – Relies on something specific – Out competes generalist • Generalist – Doesn’t rely on anything specific – Out adapts specialist Direct/specialist relationship Food webs are sometimes simplified (conceptually) to the drama of a single predator-prey interaction but, these are the (proverbial) tip of the iceberg. Ecological community interactions are extremely complex… Food web interactions can be: Direct and/or indirect. Acute and/or chronic. Spatially distinct and/or diffuse. Multigenerational and/or unique to a particular moment How are communities regulated? Keystone Species: Species that an entire ecosystem’s health depends on Regulation of community structure… Top-down regulation (trophic cascade) : keystone species are predators Pisaster (starfish): Keystone Predator? Robert Paine (1969) Effects of removing a Keystone species Wolves as a Keystone Predator Yellowstone wolves control elk populations in two important ways: 1)Elk population numbers are reduced 2)Modify elk behavior The Ecology of Fear http://www.pbs.org/wnet/nature/episodes/in-the-valley-of-the-wolves/video-wolves-on-the-hunt/220/ http://www.pbs.org/wgbh/nova/wolves/lonesome.html Regulation of community structure… Bottom-up regulation… Primary producers drive community structure? Regulation of community structure… Bottom-up regulation… Primary producers drive community structure? Regulation of community structure… Keystone Herbivory Regulation of community structure… Madagascar Flying Fox: A Keystone Seed Disperser? BeaverA keystone landscape engineer Other Keystone Species The End
