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How Competition Shapes Communities

How Competition Shapes Communities. Environemental Sci pg89-92. Competition. Interaction between 2 or more species that use the same scarce resource Resources :?? Can you think of limiting resources ? Most competitive interactions do not involve fighting.

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How Competition Shapes Communities

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  1. How Competition Shapes Communities EnvironementalSci pg89-92

  2. Competition • Interaction between 2 or more species that use the same scarce resource Resources:??Can you think of limiting resources? • Most competitive interactions do not involve fighting. • Some competing species never encounter one another.

  3. Niche • The role of a species in an ecosystem -The “job” an organism performs in the ecosystem Examples of Niches: requirements for moisture, mating, space utilization, temp. range, food consumption • Also described in terms of how the organism affects energy flow within the ecosystem • Ex. herbivore, producer

  4. Niches and Competition • If niches overlap, there will be competition. RAWR!!!! Is competition more fierce between 2 of different or same species?

  5. A Species’ Niche Can Vary in Size • Cape May Warbler Niche • Nests: midsummer • Eats: small insects • Where it finds food: spruce trees Fundamental Niche- entire range of conditions an organism is potentially able to occupy within an ecosystem

  6. Dividing Resources Among Species Observation: Cape May Warblers only feed at the very top of the spruce tree???? Robert MacArthur = ecologist who studied feeding habits of 5 warbler species • All 5 species fed on insects in spruce trees (similar fundamental niches) • Each species fed at different parts of the tree (didn’t use the same resources)

  7. Realized Niche • The part of its fundamental niche a species actually occupies Why is it beneficial for the warblers to feed at different portions of the tree? • Reduces competition

  8. Barnacle Study- Read page 368

  9. Competitive Exclusion • In nature, shortage is the rule • Species that use the same resources are almost sure to compete with one another. Competitive Exclusion- elimination of one competing species • Species that uses resource more efficiently will eventually eliminate the other

  10. When Can Competitors Coexist? • If two species can avoid competition, they may coexist. • Even if fundamental niches overlap, if realized niches don’t overlap, both species can usually survive.

  11. Predation Can Lessen Competition • If predators keep one species (the better competitor) in check, other species have the chance to survive. • Predation reduces competition, so promotes biodiversity. OmmNomm Nom! Amphibians are the gummy bears of the animal world.

  12. Biodiversity 2 Components: • # different species (richness) • Relative # of each species (evenness) High biodiversity = High Productivity High biodiversity = High Stability

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