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4.2 Niches and Community Interactions

4.2 Niches and Community Interactions. Habitats and Niches. Habitat : the area where an organism lives. Includes both the biotic & abiotic factors Niche : the full range of physical & biological conditions in which an organism lives & the way in which the organism uses those conditions.

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4.2 Niches and Community Interactions

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  1. 4.2 Niches and Community Interactions

  2. Habitats and Niches • Habitat: the area where an organism lives. Includes both the biotic & abiotic factors • Niche: the full range of physical & biological conditions in which an organism lives & the way in which the organism uses those conditions

  3. What affects where an organism lives?

  4. Tolerance • Every species has its own range of tolerance, the ability to survive and reproduce under a range of environmental circumstances. • @The organism must expend more energy to maintain homeostasis, and so has less energy left for growth and reproduction. @

  5. Resources and the Niche • The term resource can refer to any necessity of life, such as water, nutrients, light, food, or space. • For plants, resources can include sunlight, water, and soil nutrients. • For animals, resources can include nesting space, shelter, types of food, and places to feed.

  6. Place in the food web Range of temp. organism needs to survive Type of food organism eats How it obtains food Who uses the organism for food Physical conditions required to survive When & how organism reproduces Niche includes…

  7. Competitive Exclusion Principle • No two species can share a niche in the same habitat!! • example is the Warblers…

  8. The Competitive Exclusion Principle • In the the experiment shown in the graph, two species of paramecia (P. aureliaand P. caudatum) were first grown in separate cultures (dashed lines) . In separate cultures, but under the same conditions, both populations grew. • However, when both species were grown together in the same culture (solid line), one species outcompeted the other, and the less competitive species did not survive.

  9. Community interactions, such as competition, predation, and various forms of symbiosis can powerfully affect an ecosystem. Community Interactions

  10. Competition: occurs when organisms of the same or different species attempt to use a resource at the same place and time. @Direct competition between different species almost always produces a winner and a loser—and the losing species dies out. @ Competition Trees in competition for light

  11. Predation: one organism captures and feeds on another @Predators can affect the size of prey populations in a community and determine the places prey can live and feed.@ Predation Lynx and Hare

  12. Keystone Species • Sometimes changes in the population of a single species, often called a keystone species, can cause dramatic changes in the structure of a community. • In the cold waters off the Pacific coast of North America, for example, sea otters devour large quantities of sea urchins. • Urchins are herbivores whose favorite food is kelp, giant algae that grow in undersea “forests.”

  13. Keystone Species • A century ago, sea otters were nearly eliminated by hunting. Unexpectedly, the kelp forest nearly vanished. • Without otters as predators, the sea urchin population skyrocketed, and armies of urchins devoured kelp down to bare rock. • Without kelp to provide habitat, many other animals, including seabirds, disappeared. • Otters were a keystone species in this community.

  14. Keystone Species • After otters were protected as an endangered species, their population began to recover. • As otters returned, the urchin populations dropped, and kelp forests began to thrive again. • Recently, however, the otter population has been falling again, and no one knows why.

  15. Symbiosis: Any relationship in which two species live closely together Mutualism: both species benefit Symbiosis Clownfish and sea anemone Hummingbird and Flower

  16. Commensalism: one species benefits, other neither harmed nor helped Barnacles on a whale

  17. Parasitism: one organism lives in or in another & harms it A flea or tick feeds on the blood of its host and may also carry disease-causing microorganisms Mistletoe in a tree

  18. What determines where an organism might live? • Tolerance • Resources

  19. How does predation affect the size of a community?

  20. What are the three main types of symbiosis? • Commensalism • Mutualism • Parasitism

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