Review: Carrying Capacity and Limiting Factors

Review: Carrying Capacity and Limiting Factors

By Armanda Carlsson

Carrying Capacity

​What is it?

The term carrying capacity means the number of individuals of a species that an area can support with its resources.

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Example: Imagine a fish bowl that has enough food, water, and space to support a maximum number of 6 goldfish. The area is the fish bowl. The species is goldfish. The carrying capacity for the area (fish bowl) is ​6 individual goldfish. The fish bowl only has enough resources to support 6 goldrish of less!

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An area is an actual location and can be large or small.

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Examples: a field, forest, lake, river, ​door knob, city, house, fish bowl, garden

​Location

• An area is needed for organisms to live, thrive, and reproduce.

Living area

Area:

Let's make sure you understand what "area" is describing when we talk about carrying capacity.

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A group of very specific types of organisms (living things) that can reproduce.

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Examples: European Rabbits, dogs, Red Bellied Toads, Humans​

​Species

​A single organism (living thing).

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Examples: 1 rabbit, 1 goldfish, 1 middle schooler, 1 bacterium , 1 tree, one sunflower

​Individual

Individual and Species

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Multiple Choice

What does the term "carrying capacity" refer to?

• The number of resources that is needed to support a population of animals.

• The amount of plants that can feed primary consumers.

• The number of individuals of a species that an area can support with its resources.

• The area of land that a population of mammals lives on.

Multiple Choice

Identify the carrying capacity in the following scenario:

A stream in San Isabelle National Forest can support a population of 16 racoons by providing 4 fish per day for each racoon to eat. What is the carrying capacity?

• The stream

• 16 racoons

• 4 fish

• San Isabelle National Forest

Multiple Choice

Identify the area in the following scenario:

A stream in San Isabelle National Forest can support a population of 16 racoons by providing 4 fish per day for each racoon to eat. What is the carrying capacity?

• 16 racoons

• The stream

• San Isabelle National Forest

• 4 fish

Multiple Choice

How many individuals are discussed in the following scenario:

A stream in San Isabelle National Forest can support a population of 16 racoons by providing 4 fish per day for each racoon to eat. What is the carrying capacity?

• 16 racoons

• racoons

• San Isabelle National Forest

• fish

​WHAT ARE LIMITING FACTORS?

​All living things need food, water, shelter and space to survive. As long as organisms have all of these things available to them their population will continue to grow. However, populations cannot grow forever. Some form of environmental resistance will stop the population’s growth. The form of environmental resistance is called a limiting factor since it limits the population. However, limiting factors may also increase a population.

Subject | Subject

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Limiting Factors

​What are they in a nutshell?

They are reasons that may prevent a population of a species from thriving and reproducing. Having said this, it is important to understand that limiting factors will sometimes decrease population sizes, while other populations may thrive and even OVERPOPULATE an area.

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​temperature, wind, climate, sunlight, rainfall, soil, natural disasters, natural disasters, and pollution

​Abiotic (non-living)

​ Food, availability of mates, disease, and predators.

​Biotic (living/once alive)

There are TWO types of limitiing factors

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Multiple Choice

What type of factor is the following:

hurricane

• biotic

• abiotic

Multiple Choice

What type of factor is the following:

berries

• biotic

• abiotic

Multiple Choice

What type of factor is the following:

a cave system that bats live in

• biotic

• abiotic

Multiple Choice

What type of factor is the following:

A pack of wolves

• biotic

• abiotic

Multiple Choice

What type of factor is the following:

A polluted lake

• biotic

• abiotic

​REMEMBER!!!

Limiting factors will either LIMIT or INCREASE the size of a population. The ideal size of a population is

• The carrying capacity number (the number of individuals that​ an area can support) OR

• Slightly BELOW the carrying capacity number

• A population size that exceeds the carrying capacity number may damage the health of a local ecosystem. When there are too many individual of a species in a given area, the area is OVERPOPULATED! Too few individuals of a species, the area is UNDERPOPULATED

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​Density-independent factors have an impact on the population, whether the population is large or small, growing or shrinking. The size of a population does not matter! The limiting factor will effect a species population whether there are 1 individual or 100s of individuals.

​Independent

Limiting factors where the effects on the size or growth of a population vary with the density of the population itself.

​Dependent

Density Dependent and Independent Factors!

​Density-independent factors are normally abiotic factors.

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• Weather, natural disasters, altitude, pollution, ​human activity such as mining or urban construction (building of roads and structures)

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​Independent

Density Dependent factors are normally BIOTIC factors- having to do with living things.

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• Food availability, predation, ​competition between individuals for food and shelter.

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​Dependent

Density Dependent and Independent Factors!

Let's try to identify some limiting factors

Multiple Choice

Mountain chickadees compete for a special kind of nest site—tree holes. These little cavities are excavated and then abandoned by woodpeckers. Scientists who added new nest sites in one expanse of forest saw the chickadee nesting population increase significantly.

What limiting factor helped the population INCREASE?

• baby chickadees

• tree holes nests

• seasons

• weather

Multiple Choice

Mountain chickadees compete for a special kind of nest site—tree holes. These little cavities are excavated and then abandoned by woodpeckers. Scientists who added new nest sites in one expanse of forest saw the chickadee nesting population increase significantly.

Is the limiting factor BIOTIC or Abiotic?

• biotic

• abiotic

Multiple Choice

Mountain chickadees compete for a special kind of nest site—tree holes. These little cavities are excavated and then abandoned by woodpeckers. Scientists who added new nest sites in one expanse of forest saw the chickadee nesting population increase significantly.

Is the limiting factor DEPENDENT or INDEPENDENT?

• dependent

• independent

Multiple Select

A devastating tornado ripped through Townsville and hit the nuclear powerplant. This cause a meltdown that polluted the environment with deadly radiation. The population of humans had to relocate to the neighboring town of Springfield. The local animal populations became sick and the plants populations began to suffer.

What are the limiting factors (there are TWO) in this scenario?

• The tornado

• The humans

• Radiation pollution

• animals and plants

Multiple Choice

A devastating tornado ripped through Townsville and hit the nuclear powerplant. This cause a meltdown that polluted the environment with deadly radiation. The population of humans had to relocate to the neighboring town of Springfield. The local animal populations became sick and the plants populations began to suffer.

Are these limiting factors biotic or abiotic?

• biotic

• abiotic

Multiple Choice

A devastating tornado ripped through Townsville and hit the nuclear powerplant. This cause a meltdown that polluted the environment with deadly radiation. The population of humans had to relocate to the neighboring town of Springfield. The local animal populations became sick and the plants populations began to suffer.

Are these limiting factors dependent or independent?

• dependent

• independent

Multiple Select

A small furry rodent found in eastern Greenland is called the collared lemming. The population goes through a boom-and-bust cycle every four years. The lemming population grows to as much as 1,000 times its initial size, then crashes. When the lemming population is very large, the predator populations also increase. This increase in predator populations are what leads to the population crash.

What is the limiting factor? (there are TWO and one is tricky!)

• food availability

• predator numbers

• Population size of the lemmings

• four years

Multiple Choice

A small furry rodent found in eastern Greenland is called the collared lemming. The population goes through a boom-and-bust cycle every four years. The lemming population grows to as much as 1,000 times its initial size, then crashes. When the lemming population is very large, the predator populations also increase. This increase in predator populations are what leads to the population crash.

Are these limiting factors biotic or abiotic?

• biotic

• abiotic

Multiple Select

A small furry rodent found in eastern Greenland is called the collared lemming. The population goes through a boom-and-bust cycle every four years. The lemming population grows to as much as 1,000 times its initial size, then crashes. When the lemming population is very large, the predator populations also increase. This increase in predator populations are what leads to the population crash.

Are these limiting factors dependent or independent?

• dependent

• independent

Multiple Choice

The city or Townsville wants to expand its city limits to include a new housing development. The Mayor has identified a meadow of trees as the ideal location. The meadow provides living habitats for squirrels, grass toads, a small population of foxes, and a large population of field mice. The population sizes of all of these species are projected to decrease when the housing development is complete.

What is the limiting factor in this scenario?

• space

• trees

• The Mayor

• The foxes

Multiple Choice

The city or Townsville wants to expand its city limits to include a new housing development. The mayor has identified a meadow of trees as the ideal location. The meadow provides living habitats for squirrels, grass toads, a small population of foxes, and a large population of field mice. The population sizes of all of these species are projected to decrease when the housing development is complete.

Is the limiting factor biotic or abiotic?

• biotic

• abiotic

Multiple Choice

The city or Townsville wants to expand its city limits to include a new housing development. The mayor has identified a meadow of trees as the ideal location. The meadow provides living habitats for squirrels, grass toads, a small population of foxes, and a large population of field mice. The population sizes of all of these species are projected to decrease when the housing development is complete.

Is the limiting factor dependent or independent?

• dependent

• indededent

Poll

Do you feel comfortable with carrying capacity and limiting factors?

• yes

• no

• somewhat