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Predation

Predation. Predation. Predation. Predation may affect the outcome of competitive interactions In the rodent, ant, and seed example, predation by rodents affected the outcome of competition between plants…. competition. rodents. ants. predation. predation. small seeded plants. large

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Predation

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  1. Predation

  2. Predation

  3. Predation • Predation may affect the outcome of competitive interactions • In the rodent, ant, and seed example, predation by rodents affected the outcome of competition between plants…

  4. competition rodents ants predation predation small seeded plants large seeded plants competition Predation

  5. Predation • In the absence of rodents, large-seeded plants out-competed small-seeded plants • Predation by rodents prevented this competitive exclusion

  6. competition ants predation large seeded plants competitive exclusion Predation

  7. Predation • In more complex systems, predation by a “top predator” may prevent competitive exclusion… • “Cropping” of the competitively superior species increases species richness in communities…

  8. Predation the “rocky intertidal” community rocky intertidal view here

  9. Predation limpets worms chitons The rocky intertidal-high species richness; a complex food web anemones snails

  10. mussels Predation barnacles

  11. Predation Sea Star - the top predator

  12. Predation sea star predation snails chitons fan worms mussels anemones limpets snails barnacles competition for space

  13. Predation chitons, limpets, snails, fan worms, anemones, barnacles, mussels species richness gooseneck barnacles, mussels time predators removed

  14. Predation chitons, limpets, snails, fan worms, anemones, barnacles, mussels… A mixture… species richness gooseneck barnacles, mussels… only competitively superior species time predators removed

  15. Predation The effect of the predator… rocky intertidal view here

  16. Predation The effect of the predator… rocky intertidal view here The “cropping principle”

  17. Biomes - southwestern deserts the environment acts as a predator…

  18. Succession • Succession… • the more or less orderly sequence of stages or community types • that occupy newly created habitat • or that “invade” a habitat following a disturbance

  19. Succession • Primary succession takes place in area that has not previously supported a community:

  20. Succession

  21. Succession • Secondary succession takes place after a disturbance and replaces the community that occupied a location prior to disturbance…

  22. Succession old ag field figure here

  23. Succession old ag field figure here

  24. Succession

  25. Succession • “Tolerance” refers to the ability of species to tolerate environmental conditions • “Facilitation” refers to the modification of the habitat by colonizing species • “Inhibition” refers to the negative effects of modification of the environment on the species that cause the modifications.

  26. Succession • Colonizing species are more tolerant of the harsh environmental conditions in disturbed sites than equilibrium species; • Colonizing species are less shade tolerant than equilibrium species, so the growth of colonizing plants that shade the soil surface inhibits further colonization by those species, • but this growth facilitates colonization by equilibrium species that are better competitors for light and are more shade tolerant.

  27. Succession lake michigan view here Lake Michigan

  28. Succession Marram grass (AKA Sand reed) stabilizes dunes Other grasses (e.g. LBS) colonize

  29. Succession lake michigan sand grass here sand plum, juniper, willow…

  30. Succession lake michigan shrubs and grass here A mixture…

  31. Succession cottonwoods, pines

  32. Succession hardwoods, e.g. beech and maple dominate the “climax community”

  33. species richness time Succession equilibrium species colonizing species disturbance

  34. species richness time Succession a mixture of colonizing and equilibrium species equilibrium species colonizing species disturbance

  35. Disturbance • Disturbance may obliterate all or part of an ecological community and restart the course of succession

  36. Disturbance • Disturbance may obliterate all or part of an ecological community and restart the course of succession • Disturbance is a density independent, catastrophic event that affects both colonizing and equilibrium species

  37. Disturbance • Disturbance may obliterate all or part of an ecological community and restart the course of succession • Disturbance is a density independent, catastrophic event that affects both colonizing and equilibrium species • storm, flood, fire…

  38. Disturbance

  39. Disturbance • The frequency of disturbance affects the ecological community that occupies a habitat… • for instance movement of boulders…

  40. Disturbance the “rocky intertidal” community rocky intertidal view here

  41. Disturbance species richness low high frequency of disturbance mass of boulder high low

  42. Disturbance species richness equilibrium species colonizing species low high frequency of disturbance high mass of boulder low

  43. Disturbance a mixture… species richness low high frequency of disturbance mass of boulder low high

  44. Disturbance • Disturbance may obliterate all or part of an ecological community and restart the course of succession • Disturbance is a density independent, catastrophic event that affects both colonizing and equilibrium species • storm, flood, fire… • movement of boulders… • treefall…

  45. Disturbance Tall trees… Nutrient-poor soil… Shallow root systems… Lots of vines and epiphytes (“support parasites”)… Lots of wind and rain…

  46. Disturbance Tall trees… Nutrient-poor soil… Shallow root systems… Lots of vines and epiphytes (“support parasites”)… Lots of wind and rain… Tree fall… …disturbance is thought to promote the great species richness of tropical forests…

  47. Disturbance Treefall is a disturbance that creates gaps in the forest

  48. Disturbance restarts the process of succession; the forest is a mosaic of patches in different stages of succession… Disturbance

  49. Disturbance a mixture… species richness low high frequency of disturbance the “intermediate disturbance” hypothesis

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