Chapter 50—Introduction to

Ecology & the Biosphere

“It’s not a vacuum out there: how organisms interact with each other

and the environment…”

I. Life is so…Organized

• Molecules

• Cells

• (Tissues → Organ → Organ systems)

• Organisms

• Populations

• Community

• Ecosystem

• Biosphere

Ecology

• Scientific study of interactions between organisms & their environment

– these interactions

determine the

distribution & abundance of

organisms

Figure 50.1

Environmental Factors

• Abiotic factors– non-living chemical & physical factors

• temperature

• light

• water

• nutrients

• Biotic factors– living components

• animals

• plants

II. Factors Affecting Distribution of Organisms

• Distinct global & regional patterns exist in the

distribution of organisms

Figure 50.4

Terrestrial Biomes

Figure 50.24

Aquatic Biomes

Factors Limiting Geographic

Distribution

Figure 50.5

Biotic Factors• Competitors

• Predators

• Parasites

• Pollinators

• Food sources

Conclusion?

Figure 50.9

Predator-removal experiments

Abiotic Factors

• Climate

– prevailing weather conditions in an area

• Temperature *

• Water *

• Sunlight

• Wind

• Physical factors

– Rocks, soil,

nutrients

Why?

Effects of Climate

Figure 50.10

How can we explain

areas that overlap?

Global Climate Patterns• Largely determined by sunlight & Earth’s movement in

space

Figure 50.11

Seasonal Changes• Angle of the earth’s axis is responsible for seasonal

variations on Earth

Figure 50.12

Localized Effects on Climate

Figure 50.14

Localized Weather—Washington

State

Lake Stratification & Seasonal Turnover

Figure 50.15

• Ponds and lakes are sensitive to seasonal temperature change.

• Turnover brings oxygenated water from the surface of lakes to the bottom and nutrient-rich water to the top.

Lake Stratification & Seasonal Turnover

Figure 50.15

Lake Stratification & Seasonal Turnover

Figure 50.15

Lake Stratification & Seasonal Turnover

Figure 50.15

Why is this process important?

III. Aquatic & Terrestrial Biomes

Freshwater Biomes• Standing water (lakes, ponds)

• Moving water (rivers, streams) Zonation in a Lake

What characteristics

contribute to the

distribution of

organisms?

Figure 50.18

• Lakes

– Oligotrophic

• nutrient poor

• oxygen rich

– Eutrophic

• nutrient rich

• oxygen poor

Mesotrophic

Wetlands

• marshes, swamps, bogs,

seasonal pools, flood plains

Estuaries

• mudflats, salt marshes

Marine Biomes

Figure 50.22

Marine

intertidal

coral reef

benthos