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Community

Community. Contains populations of different species that interact with each other. ENVH 4387 Biological Analysis. 1. Community. These interactions among species are a major determinant of community composition beneficial negligible adverse. 09/10/95. ENVH 4387 Biological Analysis. 2.

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Community

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  1. Community • Contains populations of different species that interact with each other ENVH 4387 Biological Analysis 1

  2. Community • These interactions among species are a major determinant of community composition • beneficial • negligible • adverse 09/10/95 ENVH 4387 Biological Analysis 2

  3. Interspecific Competition • Competition between species for a limited resource • Both species populations are smaller than they would otherwise be • An important factor in the structure of communities 09/10/95 ENVH 4387 Biological Analysis 3

  4. Principle of Competitive Exclusion • For two species to coexist in the same habitat they must need/use different resources • Both species can survive only when both species limit their own population growth more than they limit that of the other species 09/10/95 ENVH 4387 Biological Analysis 4

  5. Ecosystems • Diversity of habitats is necessary to make a community • Populations of two species cannot coexist indefinitely in exactly the same habitat unless their demands for resources differ at least to some extent • If there is any degree of competition between them this will tend to slow down the rates at which both populations can increase in numbers 09/10/95 ENVH 4387 Biological Analysis 5

  6. Niche • a measure of the amount of a set of resources that is used by a population • the relative positions of the supply and demand curves indicate the severity of competition • there is only one species per niche 09/10/95 ENVH 4387 Biological Analysis 6

  7. Niche • implies that species do not occur at random within a community • there is a definite pattern imposed by the interactions that a population has with • the physical and chemical conditions of its habitat and • interactions with populations of other species 09/10/95 ENVH 4387 Biological Analysis 7

  8. Summary • the interaction of species with their surroundings (abiotic and biotic) determines the survival of that species • survival of certain species and death of other species result in the community structure 09/10/95 ENVH 4387 Biological Analysis 8

  9. Summary • changes in community structure influenced by any force (including anthropogenic) affecting the abiotic and biotic components of an ecosystem • theoretically changes in community structure (such as diversity) is a potential indicator of adverse forces 09/10/95 ENVH 4387 Biological Analysis 9

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