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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