Keystone and Foundation Species 2011
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Keystone and Foundation Species 2011

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Examples of keystone and foundation species.

Examples of keystone and foundation species.

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Keystone and Foundation Species 2011 Keystone and Foundation Species 2011 Presentation Transcript

  • Keystone or Foundation Species?
  • Keystone or Foundation?
    • Keystone
    • Pisaster ochraceus is an efficient predator of the common mussel, Mytilus californicus .
    • It reduces abundance of M. californicus , allowing other macroinvertebrates to persist.
    • If Pisaster present = diverse intertidal community.
    Based on the research of Dr. Robert T. Paine
  • Dr. Robert T. Paine’s Work (a) The sea star Pisaster ochraceous feeds preferentially on mussels but will consume other invertebrates. With Pisaster (control) Without Pisaster (experimental) Number of species present 0 5 10 15 20 1963 ´64 ´65 ´66 ´67 ´68 ´69 ´70 ´71 ´72 ´73 (b) When Pisaster was removed from an intertidal zone, mussels eventually took over the rock face and eliminated most other invertebrates and algae. In a control area from which Pisaster was not removed, there was little change in species diversity.
  • Keystone or Foundation?
    • Keystone
    • Removing three species of kangaroo rats changed a desert plain into an arid grassland. In areas without kangaroo rats, grasses filled in between the shrubs, stems and other plant litter accumulated, large-seeded plants replaced those with smaller seeds, snow melted more slowly and the numbers of the other rodents increased significantly.
    Based on the research of Dr. James H. Brown
  • Keystone or Foundation?
    • Keystone (engineer)
    • Pdog burrows act as homes to other creatures, including burrowing owls, badgers, rabbits, black-footed ferrets, snakes, salamanders, and insects.
    • Their burrowing activity works to loosen and churn up the soil, increasing its ability to sustain plant life.
    • Their foraging and feeding practices enable a more nutritious, diverse and nitrogen-rich mixture of grasses and forbs (broad-leafed vegetation) to grow.
  • Keystone or Foundation?
    • Foundation
    • Dominant primary producer that provides food and shelter for many other species
    Kelp
  • Effects of losing the “keystone” predator…
    • A trophic cascade-
    • in a food web, the cascading effect that a change in the size of one population (usually an apex predator) in the web has on the populations at lower levels.
    Example: Gray Wolf in Yellowstone National Park (Wolf -> Elk -> Cottonwood/Aspen/Willow --> Bird Populations)
  • Don’t forget…
    • A keystone species is one that has a disproportionate impact on its ecosystem when compared to its abundance.
    • A foundation species is usually a primary producer that dominates an ecosystem in abundance and influence.
  • Sources
    • http://www.washington.edu/research/pathbreakers/1969g.html (starfish)
    • http://query.nytimes.com/gst/fullpage.html?res=9C0CE1DB1530F936A15751C1A966958260 (kangaroo rats)
    • http://www.prairiedogs.org/keystone.html (praire dogs)
    • http://www.eoearth.org/article/Global_marine_biodiversity_trends (kelp)