Module 3 Intro

1. Module 3 Intro

1.25. Page 2

Lesson 5

Module 3—Ecosystem Diversity

Explore

Read

A stand of yellow-leaved aspen trees in their fall colours is shown in this photograph. This photo is of tomatoes growing in a greenhouse with a glass roof. An Arctic fox is in this photograph.

In Lesson 4 you looked at how biotic and abiotic factors influence biomes, habitats, and niches. In Lesson 5 you will examine what biotic and abiotic factors limit growth in an ecosystem.

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, interactions between organisms are affected. Start Lesson 5 by reading “Factors Limiting Growth in Ecosystems,” “Abiotic Limiting Factors,” and “Biotic Limiting Factors” from page 98 of the textbook to page 103. At this time, you do not need to read “Thought Lab 3.2.”

Self-Check

SC 1. Hypothesize why trembling aspen do not live everywhere in Canada.

SC 2. Why is unlimited growth impossible?

SC 3. What abiotic factors would limit the growth of greenhouse tomatoes?

SC 4. What biotic factors would cause population growth to slow down?

SC 5. Identify and explain the limiting effects of introducing Arctic foxes to the Aleutian Islands.

Check your work.

Self-Check

SC 1. Here is one hypothesis: Trembling aspen do not live everywhere in Canada because they require certain growing conditions, which are dictated by abiotic factors.

SC 2. 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.

SC 3. Soil (nutrients), temperature, moisture, humidity, altitude, the amount of CO2, and the available solar energy would limit tomato growth.

SC 4. 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.

SC 5. 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.

Watch and Listen

You will now watch an animation about regulating population size.

Self-Check

SC 6. Complete this Self-Check exercise.