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Competition . Coastal sage scrub – note bare spots near shrubs. Rabbit grazing – source of apparent competition . Species Coexistence. Serengeti National Park . Species Coexistence.

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  1. Competition

  2. Coastal sage scrub – note bare spots near shrubs

  3. Rabbit grazing – source of apparent competition

  4. Species Coexistence Serengeti National Park

  5. Species Coexistence Competition is a common feature of species interactions, yet often we find very similar species coexisting in nature, species that seem to need the same resources. How do they coexist? • Refuge from competition • Predation keeps populations of each species low enough that they do not compete • Resources may be variable in space and time, so that the species coexist because both do not find resource at same time

  6. Dung – a valuable, variable resource Dung Beetles Dung Fly

  7. Predation Great White Shark and Fur Seal

  8. Lions hunting – True Predator

  9. Moose Browsing – Partial Predator

  10. Parasitoid Wasp

  11. Specialists and Generalist Predators Advantages to being a specialist 1. Avoid interspecific competition 2. Allows evolution to overcome chemical defense 3. Allows evolution of cryptic coloration that matches prey - mostly for insects on plants 4. Increases chance of mate encounter Advantages of being a generalist 1. Flexibility in face of environmental uncertainty 2. Broad diet needed to get all necessary nutrients and vitamins 3. Avoid overdosing on any one toxin - mostly for animals grazing on chemically defended plants

  12. Pied Wagtail

  13. Caribou eating lichens

  14. Edible mussel – Mytilus edulis

  15. Black oystercatcher

  16. Bluegill sunfish

  17. Mink Muskrat

  18. Red grouse in heather

  19. Bank vole Tawny Owl

  20. Cinnabar Moth and Caterpillar on Ragwort Tansy

  21. Snowshoe hare and Lynx

  22. Lynx Ruffed Grouse Snowshoe hare

  23. Sea Otter

  24. Sea Urchin

  25. Kelp Forest

  26. Sea Otter eating Sea Urchin in Kelp Forest

  27. Comparison of kelp and urchin biomass with and without sea otters

  28. Kelp forest ecsystems with and without sea otters

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