2.2.1 Population Changes

Population Changes

2.2.1

Objectives

Learners can:

• identify aspects of a population that scientists study

• determine how abiotic factors impact the growth of populations

• evaluate the impact humans have on the growth of a population

• abiotic

• habitat

• population

Prerequisite Vocab

• overpopulation

New Vocab

Vocabulary

when a population has exceeded the resource limits of an ecosystem

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Overpopulation

Word Cloud

If you could be any animal, alive or extinct, what would you be?

Generally, growing populations of native organisms is a sign that an ecosystem is healthy. However, if the populations of native organisms are decreasing, this encourages scientists to investigate what might be causing disruptions in that environment.

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Population Ecology

This gives ecologists an idea of whether the ecosystem is balanced or unbalanced.

Population Size

The amount of area a population takes up can indicate the success of the ecosystem.

Population Area

If a native population is growing or shrinking and how quickly it is happening can be indicative of the health of the ecosystem.

Population Growth

​Population Factors

Multiple Choice

Which of the following data would a population ecologist most likely collect?

• amount of pollution in the water

• air quality of the atmosphere

• number of individuals in an ecosystem

• geological features in an ecosystem

Shrinking population numbers may indicate the potential for extinction, while a growing population can indicate a healthy environment.

Overpopulation occurs when a population has exceeded the resource limits of an ecosystem. When too many organisms are present in an area, some will need to leave, or they will die because of a lack of resources.

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Population Predictions

Multiple Choice

Why would scientists be interested in species populations that are either growing too much or shrinking too much?

• Both types of changes may indicate concerns about the health of an ecosystem.

• Once a population is established, it will only grow and never shrink in size.

• 
  While populations can grow without impacting the ecosystem, shrinking populations could lead to extinction.

• 
  These population changes show that the ecosystem is healthy.

Many marine organisms are sensitive to even small changes in water temperature. Changes in ocean temperature have forced animals such as dolphins and whales to new areas because their food sources are not able to survive in their normal ocean depths.

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Climate Changes

It is estimated that at one time the western plains of the United States supported between 15 billion and 100 billion bison. However, overhunting in the 1800s significantly impacted the American bison population. By 1889, there were only about 1,000 bison remaining. This significant decline in population size, and potential for extinction, motivated the U.S. government and landowners to try to address the issue.

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AmericanBison

In the early 1900s, laws and regulations were established to protect the American bison from extinction. Due to these protections, the bison population grew significantly. The population of American bison experienced exponential growth.

Exponential growth often begins small, but later growth is much higher. Exponential growth occurs regularly in nature, especially when resources are plentiful and there are few threats to a population.

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American Bison

Multiple Choice

What effect does the exponential growth of invasive species have on an ecosystem?

• The populations of invasive species and native species do not interact with each other.

• The population growth of invasive species will have little impact on the overall ecosystem.

• The populations of invasive species will outgrow those of native species.

• The populations of native species will keep up with the growth of the populations of invasive species.