Biology 12

13.1 Where on Earth Do You Find Organisms?

430 MHR • Unit 5 Population Dynamics

Ecologyis often described as the study of the

patterns of distribution and abundance of plants,

animals, and other types of organisms on Earth

(see Figure 13.1). Since these patterns depend on

interactions among organisms as well as between

individuals and their environments, ecology also

includes the study of these interactions.

It is important to realize that the environment of

every organism includes other organisms as well as

the air, soil, or water that surrounds it. In other

words, an organism’s environment includes

biotic and abiotic components. As you learned

in previous studies, the bioticcomponents are

the living things with which the organism interacts,

such as those it consumes or is consumed by,

competes with or is helped by, and parasitizes

or is host to. The abioticcomponents are all non-

living physical and chemical factors that influence

an organism’s survival, such as temperature, light,

water, and nutrients.

EXPECTATIONS

Distinguish between abiotic and biotic components of the environment.

Describe populations and their interrelationships within communities

and ecosystems.

Describe the process of ecological succession.

Differentiate between the habitat, range, and niche of a population.

Figure 13.1As shown in this satellite photograph, life is not uniformly distributed

throughout the biosphere. The dark green areas are nutrient rich, while the yellow

areas are relatively barren.