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Predation PowerPoint Presentation

Predation

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Predation

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  1. Predation Great White Shark and Fur Seal

  2. Lions hunting – True Predator

  3. Red squirrel – true predator

  4. Moose Browsing – Partial Predator

  5. Cookie-cutter shark – Partial Predator

  6. Parasitoid Wasp

  7. 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

  8. Factors affecting predator behavior 1. Search time - the amount of time spent looking for food items 2. Handling time - the amount of time spent capturing prey once it is found, also includes time for consuming prey and time to digest before a predator can search for food again

  9. Birds gleaning for insects - generalist

  10. Lions – specialize a bit

  11. Black-footed ferret – specialist – 90% of diet is prairie dogs

  12. Predator-Prey Interactions

  13. Food Preferences • A preference exists if the proportion of a type of food is higher in the animal’s diet than it is in its proportion in the environment • Ranked preference – predator preferentially eats prey which is most valuable (usually in terms of calories) • Balanced preference – predator eats prey items that provide integral parts of a balanced and mixed diet (usually in terms of nutrients and vitamins)

  14. Pied Wagtail

  15. Caribou feeding in winter

  16. Preferences • Fixed preference – predator eats certain items regardless of what else is available – can be fixed in terms of species consumed or energy consumed

  17. Edible mussel – Mytilus edulis

  18. Shore crab and edible mussels

  19. Backswimmers

  20. Asellus aquaticus – prey for backswimmers

  21. Guppy as predator

  22. Guppy prey – tubificid worms and fly larvae

  23. Eurasian oystercatcher

  24. Search image – this image has dashes arranged as L, as T, and plus signs – can you find the Ts?

  25. Bluegill sunfish

  26. Effects on populations • Population regulation refers to the tendency of a population to decrease in size when above a particular level, and to increase in size when below that level. Population regulation can only occur as a result of one or more density dependent processes acting on birth or death rates.  • Population abundance is determined by the combined effects of all factors and processes that influence population size, whether they are density dependent or density independent.

  27. Predator effect on individual prey

  28. Mink Muskrat

  29. Arctic Ground Squirrel – Predator population is self-limited

  30. Red Grouse in Heather –Predator population is self-limited

  31. Predator Switching Regulates Prey Population Bank vole Tawny Owl

  32. Cinnabar Moth and Caterpillar on Ragwort Tansy

  33. Snowshoe hare and Lynx

  34. Lynx Ruffed Grouse Snowshoe hare

  35. Sea Otter

  36. Sea Urchin

  37. Kelp Forest

  38. Sea Otter eating Sea Urchin in Kelp Forest

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

  40. Sea Urchin Barren

  41. Kelp forest ecsystems with and without sea otters