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ENVIRONMENTAL SCIENCE
Chapter 5
Sections 1 & 3
HABITATS AND NICHES
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A NICHE is the role of an organism in the ecosystem
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A niche is more than a habitat, it is also what the organism does within its habitat
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A niche includes BIOTIC FACTORS and ABIOTIC FACTORS
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No two species can share the same niche in the same habitat
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http://www.youtube.com/watch?v=Pt0lZZ_QMf4
HABITATS AND NICHES
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If two species do, they will COMPETE for RESOURCES
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The extinction of a population due to direct competition with another species is called
COMPETITIVE EXCLUSION
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Competitive exclusion refers to the extinction of a species in a particular place, not the
whole species
HABITATS AND NICHES
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A FUNDAMENTAL NICHE is the theoretical niche an organism could be in
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A REALIZED NICHE is where the organism actually is
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See figure 5.3
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NICHE DIVERSITY is relative to the abiotic factors of an ecosystem
HABITATS AND NICHES
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A PREDATOR is an organism that actively hunts other organisms
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PREY is the hunted
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A predator that promotes niche diversity is called a KEYSTONE PREDATOR
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See Fig 5.4
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http://www.youtube.com/watch?v=_IWw8Ruz8Uo
POPULATION GROWTH
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Population growth in which the rate of growth in each generation is a multiple of the
previous is called EXPONENTIAL GROWTH
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This can only happen if food and other resources were not limited
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See fig 5.8
CARRYING CAPACITY
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The number of individuals of a species that can be supported by an ecosystem is called
CARRYING CAPACITY
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Growth stops when # of births = # of deaths
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See fig 5.9
LIMITING FACTORS
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Limiting factors that are dependent on population size are called DENSITY-DEPENDENT
LIMITING FACTORS
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Examples are PREDATION, PARASITISM, DISEASE, FOOD COMPETITION, LIVING
SPACE, WATER AVAILABILITY
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Limiting factors that affect the same percentage of a population , regardless of size are
called DENSITY-INDEPENDENT LIMITING FACTOR
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Examples are CLIMATE, HUMAN DISTURBANCE, AND NATURAL DISASTERS
LIMITING FACTORS
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Populations controlled by density-dependant factors show an S-shaped curve (fig 5.9)
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Populations controlled by density-independent factors show a boom and bust curve (see
fig 5.11)