1. Ecology
Module 15

2. Organization of the Biosphere
Levels of organization
Biosphere
Biome
Ecosystem
Biotic factors – living
Abiotic factors – non living
Community
Population
Organism

3. The ecological “niche”
Every organism in a community has a specific NICHE:
The organism’s ROLE in the ecosystem -
Habitat
Place in food web
Interrelationships

4. Transfer of Energy An ecosystem’s ultimate source of energy is the SUN
Solar energy is used by “producers” to make food.
“Consumers” eat producers (or other consumers) to gain food.
Each step in the food web is called a TROPHIC LEVEL

5. Transfer of Energy
Arrows show the transfer of energy from one organism to another
Energy moves in
ONE DIRECTION!

6. Transfer of Energy Ecological Efficiency
Only about 10% of the available energy in one trophic level is passed to the next trophic level
The “lost” energy is used for biological work (eating, growing, respiring, etc) and is converted to HEAT.
Tertiary
consumers
LEAST energy
Secondary consumers
Primary consumers
Producers
MOST energy

7. Cycling of Matter Role of Decomposers
Break down wastes and dead organisms
Decomposition allows nutrients to be returned to the soil and reused
Includes bacteria, fungi, and some invertebrates

8. Biogeochemical Cycles
Water Cycle:
Nitrogen Cycle:

9. Biogeochemical Cycles
Carbon Cycle:
Driven by photosynthesis and cellular respiration
Decomposition is a form of cellular respiration
Fossil fuel combustion adds CO2 to atmosphere
Deforestation removes trees that should remove CO2

10. Community Interactions
Competition
Predation
Symbiosis
Organisms in a community interact with each other in many ways. Some of these interactions include:
Competition
Predation
Symbiosis

11. Community Interactions
Competition A struggle for resources (food, space, abiotic factors, mates)

12. Community Interactions
Predation Some organisms (predators), consume others (prey)

13. Community Interactions
Symbiosis A close, permanent relationship between 2 organisms – NOT predation or competition!
Mutualism (+,+) Parasitism (+,-) Commensalism (+, 0)

14. Population Growth J-Curve: S-Curve: Carrying Capacity:
The maximum number of individuals an environment can support
Exponential growth:
rapid growth in a short period of time
# organisms
# organisms
Time
Time

15. Limiting Factors – establish carrying capacity and limit the size of a population
Density Dependent:
Includes food, disease, mates
Density Independent:
Includes natural disasters

16. Population Growth Populations fluctuate around the carrying capacity….
This is called
“dynamic equilibrium”.

17. Change in COMMUNITIES over time
Succession:
Communities change over time in a predictable, orderly way over many decades
Changes in plant communities lead to changes in animal communities