1. 5-2 Limits to Growth
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2. Limiting Factors
The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient.
Limiting factor: the factor that causes population growth decline
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3. Examples of limiting factors:
Human disturbances
Competition
Predation
Parasitism and disease
Drought and other climate extremes
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4. Density-Dependent Factors
Density-dependent limiting factor: A limiting factor that depends on population size.
These factors come into play mostly with a large, dense population.
They do not affect scattered populations as much
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5. Density-dependent limiting factors include: competition predation
parasitism
disease
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6. 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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7. The more individuals that live in an area, the sooner the resources will be used up.
Example: The Atlantic puffin lives in large colonies along the coast of eastern North America from Maine to the artic. Puffins nest in burrows dug into the sides of cliffs. Because nesting sites are limited, puffins must compete for space.
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9. Competition can also occur between members of different species.
This type of competition is a major force of evolutionary change.
Over time, the species may evolve to occupy different niches.
Remember the competition exclusion principle?
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10. Populations in nature are often controlled by predation.
The regulation of a population by predation takes place within a predator-prey relationship.
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11. Parasitism and Disease
Parasites can limit the growth of a population by taking nourishment, causing the host to become weak, diseased or dead.
A parasite lives in or on another organism (the host) and consequently harms it.
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Tapeworms can be 30 ft in length.

12. Major upsets can lead to long-term declines
Density-independent limiting factors affect all populations in similar ways, regardless of the population size.
Environments are always changing, and most populations can adapt to a certain amount of change.
Major upsets can lead to long-term declines
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13. Density-Independent Factors
Examples of density-independent limiting factors include:
unusual weather
natural disasters
seasonal cycles
certain human activities—such as damming rivers and clear-cutting forests
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14. Abiotic factors Climate extremes Human disturbances Building roads
Filling wetlands
Clearing forests
Biotic factors
Competition
Predation
Parasitism
Disease
Human disturbances
Poaching
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15. 5-2
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16. 5-2
A limiting factor that affects all populations in similar ways regardless of their size might be
drought.
disease.
predation.
crowding.
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17. 5-2
Which of the following would be a limiting factor affecting the panda population of China?
programs that educate people about endangered species
capture of some pandas for placement in zoos
laws protecting habitat destruction
a disease that kills bamboo plants
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18. 5-2
Density-dependent factors operate most strongly when a population is
large and dense.
large but sparse.
small and sparse.
small, but growing.
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19. 5-2
Within a limited area, if the population of a predator increases, the population of its prey is likely to
increase.
decrease.
remain about the same.
become extinct.
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20. 5-2
Which of the following is a density-independent factor affecting populations?
predation
disease
a destructive hurricane
parasites
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