Unit B

Module 3 ~ Lesson 3

Limiting Factors

Living organisms have the ability to produce populations of infinite size if they are allowed to reproduce with infinite resources and space. Environments and resources, however, are finite. As a result, populations have a carrying capacity, a population size at which the population will cease growing. As population size fluctuates, interactions between organisms are affected.

Abiotic and biotic factors in the ecosystem will affect the growth, survival, and distribution of an organism. These factors are called limiting factors.

Image by Maria e Fernando Cabral from Pixabay

Abiotic Limiting Factors

View the following animation. When you arrive at the ecosystem slide, explore the possible effects of each abiotic limiting factor. What other factors might affect the populations in this ecosystem?

Read

Read "Factors Limiting Growth in Ecosystems", "Abiotic Limiting Factors", and "Biotic Limiting Factors" on pages 98 to 103 of your textbook.

Self-Check

Hypothesize why trembling aspen does not live everywhere in Canada.

Here is one hypothesis: Trembling aspen do not live everywhere in Canada because they require certain growing conditions, which are dictated by abiotic factors.

Why is unlimited growth impossible?

Populations can't have sustainable long-term unlimited growth (short-term unlimited growth is possible). Limiting factors lessen the number of individuals of a population.

What abiotic factors would limit the growth of greenhouse tomatoes?

Soil (nutrients), temperature, moisture, humidity, altitude, the amount of CO ₂ , and the available solar energy would limit tomato growth.

What biotic factors would cause population growth to slow down?

Population growth would slow because of competition within a species and between species. Predation and parasitism are other biotic factors that would slow down population growth.

Identify and explain the limiting effects of introducing Arctic foxes to the Aleutian Islands.

The predator-prey relationship between the Arctic foxes and the seabirds on the islands had a limiting effect. The introduction of the foxes "limited" the populations of seabirds almost to the point of extinction. The loss of the seabirds and their guano (seabird droppings) led to the loss of the grasslands and all the organisms that depended on the grassland habitat for survival.