Module 8 Lesson 7 - 1

Get Focused

Banff National Park was established to preserve the ecosystems of a pristine wilderness in Alberta's Rocky Mountains. Hiking in the back-country of the park today gives a good chance of encountering several species of wildlife in their natural habitats.

In the national parks, a grizzly bear may upturn rotting logs looking for a meal of larvae and roots; a moose could be swarmed by mosquitoes drawing blood to feed their eggs; algae and fungi may work cooperatively to form the lichen that the caribou feed on in the winter. These are examples of relationships that exist between individuals of various species.

All organisms are part of ecological communities made of food webs specific to a defined area. Each species has a role (niche), and this interdependence can cause communities to collapse even if only one species is affected severely. The interactions and relationships are favoured as long as they give the organisms a selective advantage within their specific environment.

Each species you see in a national park has out-competed all others that have attempted to share its niche. The grizzly bears behavioural defenses are easy to see. Standing on its hind legs with hair on end makes it appear larger and more fearsome. Baring teeth, growling, laying back ears, and mock charging all indicate danger to would-be competitors or predators.

What kinds of defenses do organisms use to protect themselves from other competitors or from being consumed, thus protecting their alleles from elimination?

By the end of this lesson, you should be able to answer these focusing questions:

• What relationships exist between species and ecosystems?
• What effect do these interactions have on population changes?
• What are defense mechanisms are evident within predation and competition?