5-2 Limits to Growth Copyright Pearson Prentice Hall

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 Copyright Pearson Prentice Hall

Limiting Factors Examples of limiting factors: Human disturbances Competition Predation Parasitism and disease Drought and other climate extremes Copyright Pearson Prentice Hall

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 Copyright Pearson Prentice Hall

Density-dependent limiting factors include: competition predation parasitism disease Copyright Pearson Prentice Hall

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. Copyright Pearson Prentice Hall

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. Copyright Pearson Prentice Hall

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? Copyright Pearson Prentice Hall

Populations in nature are often controlled by predation. The regulation of a population by predation takes place within a predator- prey relationship. Copyright Pearson Prentice Hall

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. Copyright Pearson Prentice Hall Tapeworms can be 30 ft in length.

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 Copyright Pearson Prentice Hall

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 Copyright Pearson Prentice Hall

Biotic factors Competition Predation Parasitism Disease Human disturbances Poaching Abiotic factors Climate extremes Human disturbances Building roads Filling wetlands Clearing forests Copyright Pearson Prentice Hall

5-2 Copyright Pearson Prentice Hall

5-2 A limiting factor that affects all populations in similar ways regardless of their size might be drought. disease. predation. crowding. Copyright Pearson Prentice Hall

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 Copyright Pearson Prentice Hall

5-2 Density-dependent factors operate most strongly when a population is large and dense. large but sparse. small and sparse. small, but growing. Copyright Pearson Prentice Hall

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. Copyright Pearson Prentice Hall

5-2 Which of the following is a density-independent factor affecting populations? predation disease a destructive hurricane parasites Copyright Pearson Prentice Hall

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