1. 7A Ecology Basics
Subtitle

2. Levels of Ecological Organization
Individual
Population
Community
Ecosystem
Biosphere

3. Habitat VS Niche Habitat NICHE WHERE an organism lives
What an organism DOES and how it INTERACTS with the environment

4. Partitioning Sharing resources
Competitive Exclusion Principle
No two species can occupy the exact same niche
Partitioning Sharing resources

5. What affects living organisms?
Biotic Factors
Relationships between living organisms
Humans pick flowers
Coyotes eat chickens
Abiotic Factors
Physical or nonliving factors that affect living organisms
Oxygen, water, sunlight, temperature, rocks, climate, buildings

6. Biotic Factors Competition Competing for resources
Living space, food, water, mates, etc

7. Biotic Factors Predation One organism kills and eats the other
Herbivory – herbivores eating plants
Similar to predation
Mimicry – mimic a dangerous animal so that others stay away

8. Biotic Factors Parasitism
One organism feed on another (typically does not kill the host)

9. Biotic Factors Mutualism Commensalism Both organisms benefit
One organism benefits and the other is neither helped nor harmed
Crocodile and plover

10. Other Biotic Factors Disease
Spread of pathogens or disease causing agents
Bacterial or viral

11. Abiotic Factors
Oxygen
Water
Sunlight
Temperature
Rocks
Climate

12. Populations Both biotic and abiotic factors can affect population size
(+) Number of births
(-) Number of deaths
Number of organisms that (+) move in (immigration) or (-) out (emigration) of a population

13. Exponential Growth
Population under IDEAL conditions with UNLIMITED resources can grow EXPONENTIALLY
J Shaped graph

14. In The Real World… Most population do NOT have unlimited resources
Biotic factors: competition, predation, disease
Abiotic Factors: drought, temperature, water, light
All affect the growth of a population

15. Logistic Growth
Populations may experience growth, but eventually reach carrying capacity
Carrying Capacity
Maximum number of individuals a particular environment can support at a given time

16. Logistic Growth
S-Shaped Graph

17. Limiting Factor Anything that can limit population size
Density Dependent Limiting Factors
Any limiting factor that affects dense populations MORE
Disease
Overcrowding
Predators

18. Limiting Factor Density Independent Limiting Factor
Any limiting factor that affects all population equally
Flood
Tornado
Drought
Natural disasters

19. Non-Native Species
Invasive Species
Zebra Mussels

20. Stability For the most part, ecosystems are relatively stable
Most population sizes remain relatively the same over time
Only when there are changes to the ecosystem does the population sizes change

21. Stability
If a small change occurs in an ecosystem, the population may change slightly
If a dramatic change occurs in an ecosystem, the population size may change a lot