biology
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5-2 Limits to Growth
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Limiting Factors
What factors limit population growth?
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Limiting Factors
Limiting Factors
The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient.
Ecologists call such substances limiting nutrients.
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Limiting Factors
A limiting nutrient is an example of a more general ecological concept: a limiting factor.
In the context of populations, a limiting factor is a factor that causes population growth to decrease.
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Density-Dependent Factors
Density-Dependent Factors
A limiting factor that depends on population size is called a density-dependent limiting factor.
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Density-Dependent Factors
Density-dependent limiting factors include:
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Density-Dependent Factors
Density-dependent factors operate only when the population density reaches a certain level. These factors operate most strongly when a population is large and dense.
They do not affect small, scattered populations as greatly.
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Density-Dependent Factors
Competition
When populations become crowded, organisms compete for food, water space, sunlight and other essentials.
Competition among members of the same species is a density-dependent limiting factor.
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Density-Dependent Factors
Competition can also occur between members of different species.
This type of competition can lead to evolutionary change.
Over time, the species may evolve to occupy different niches.
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Density-Dependent Factors
Predation
Populations in nature are often controlled by predation.
The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control.
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Density-Dependent Factors�
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Wolf and Moose Populations on Isle Royale
Moose Wolves
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5-2 Limits to Growth
Density-Dependent Factors
Parasitism and Disease
Parasites can limit the growth of a population.
A parasite lives in or on another organism (the host) and consequently harms it.
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Density-Independent Factors
Density-Independent Factors
Density-independent limiting factors affect all populations in similar ways, regardless of the population size.
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Density-Independent Factors
Examples of density-independent limiting factors include:
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5-2
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5-2
A limiting factor that affects all populations in similar ways regardless of their size might be
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5-2
Which of the following would be a limiting factor affecting the panda population of China?
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5-2
Density-dependent factors operate most strongly when a population is
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5-2
Within a limited area, if the population of a predator increases, the population of its prey is likely to
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5-2
Which of the following is a density-independent factor affecting populations?
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