Bio150TheEcologicalNiche

Bio150TheEcologicalNiche - The Ecological Niche, Coactions...

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1 The Ecological Niche, Coactions and Community Ecology
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2 Ecological Niche Niche: the sum of all environmental factors that influence the life history of a species Abiotic Factors Conditions (not used up; temperature, relative humidity) Resources (in limited supply; moisture, space) Biotic Factors Billock
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3 Ecological Niche Fundamental niche: the entire niche that a species is capable of using, based on physiological tolerance limits and resource needs; abiotic factors only Realized niche: actual set of environmental conditions, presence or absence of other species, in which the species can establish a stable population; abiotic and biotic factors
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4 Ecological Niche Interspecific competition: occurs when two species attempt to use the same resource and there is not enough resource to satisfy both Interference competition: physical interactions over access to resources Fighting Defending a territory Competitive exclusion: displacing an individual from its part of its range
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5 Ecological Niche J.H. Connell’s classical study of barnacles
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6 Ecological Niche Other causes of niche restriction Predator absence or presence Plant species Absence of pollinators Presence of herbivores Billock Billock
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7 Ecological Niche G.F. Gause’s classic experiment on competitive exclusion using three Paramecium species shows this principle in action Principle of competitive exclusion: if two species are competing for a limited resource, the species that uses the resource more efficiently will eventually eliminate the other locally
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8
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9 Ecological Niche Niche overlap and coexistence Competitive exclusion redefined: no two species can occupy the same niche indefinitely when resources are limiting Species may divide up the resources, this is called resource partitioning Gause found this occurring with two of his Paramecium species
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10 Resource partitioning among sympatric lizard species
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11 Ecological Niche Resource partitioning is often seen in similar species that occupy the same geographic area Thought to result from the process of natural selection Character displacement: differences in morphology evident between sympatric species May play a role in adaptive radiation
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12 Ecological Niche Character displacement in Darwin’s finches
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13 Ecological Niche Detection of interspecific competition can be difficult If resources not limited there may be no competition Small versus large population size May be environmental conditions that cause the decline of a species, not competition
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14 Ecological Niche Experimental studies of competition Seed-eating rodents and Kangaroo rats 50m x 50m enclosures Enclosures had openings large enough for seed-eating rodents but not the Kangaroo rats Monitor the number of small rodents
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15 Ecological Niche Detecting interspecific competition
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16 Ecological Niche Interpreting field data: Negative effects of one species on another do not
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This note was uploaded on 09/30/2010 for the course BIO 150 taught by Professor Rayner during the Fall '10 term at Wofford.

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Bio150TheEcologicalNiche - The Ecological Niche, Coactions...

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