1. Chapter 3 Ecology

2. What is Ecology?
Ecology: The study of the interactions of organisms with one another and with their environment.
Intro to Ecology I (3:09)
Intro to Ecology II (3:07)

3. Why Study Ecology? Ecosystems are very complex.
They could contain hundreds or thousands of interacting species.
Understanding their relationships can be beneficial for all organisms within that ecosystem.

4. Why Study Ecology?
We begin understanding ecosystems by asking two questions:
Where does the energy for organisms come from?
Where do organic and inorganic substances come from for organisms?

5. Six Levels of Organization
Species – an individual (harlequin poison dart frog)
Population – group of same species living in the same ecosystem

6. Six Levels of Organization
Community – groups of different populations living in an area (pond community)
Ecosystem – communities plus the nonliving parts; first level to study nonliving (abiotic) parts

7. Six Levels of Organization
Biosphere – the atmosphere and upper crust where life can be found
Biome – groups of ecosystems found within a large geographic area; same climate and similar dominant species

8. Six Levels of Organzation

9. Energy in Ecosystems
Autotrophs/Producers The organisms that take in energy from their surroundings (light, inorganic chemicals) and store it in complex chemical compounds
Plants
Algae
Some bacteria

10. Energy in Ecosystems
Heterotrophs/Consumers Organisms that obtain their energy by consuming other organisms
Animals
Fungi
Bacteria
Plants*
* Plant exception: Carnivorous plants, like Venus fly trap; both auto- and heterotrophic

11. Energy in Ecosystems
Decomposers Organisms that obtain energy by consuming organic matter (feces, urine, dead plants and animals, etc)
Fungi
Bacteria

12. The Four Vores Herbivores: plant eaters Carnivores: meat eaters
Found at the second trophic level.
Carnivores: meat eaters
Found at the third trophic level or higher.

13. The Four Vores Omnivores: organisms that eat both plants and animals
Detritovores: organisms that eat dead and decaying plant matter

14. Ecological Pyramids
Energy pyramid 10% of energy is passed on through each trophic level; remaining energy released as heat or used by organism

15. Ecological Pyramids
Biomass pyramid: total amount of living tissue within a particular community
In this example, 10,000 g/m2 of producers are required to support only 10 g/m2 of tertiary consumers

16. Ecological Pyramids
Pyramid of numbers: displays the number of organisms located at each trophic level
Can be inverted

17. Food Chain
Food chains show the linear flow of energy within an ecosystem
Also show predator-prey relationships (who eats whom)

18. Food Web
Food web shows the movement of energy through an ecosystem via complex feeding relationships
More complex and descriptive than a food chain
Food Chains (4:50)
Food Webs (3:07)

19. Symbiosis
Symbiosis: A close long-term relationship between two or more species.
Marine Symbiosis (6:00)

20. Symbiosis: Parasitism
Parasitism: symbiotic relationship between at least two organisms where one derives benefit from the other (the host).
Parasite benefits; host is harmed

21. Symbiosis: Mutalism
Mutualism: symbiotic relationship in which all participating species benefit

22. Symbiosis: Commensalism
Commensalism: symbiotic relationship in which one species benefits and the other is neither helped nor harmed

23. The Nitrogen Cycle 78% of the atmosphere is composed of nitrogen.
The nitrogen cycle is the flow of atmospheric nitrogen through an ecosystem.
It is helped by nitrogen-fixing bacteria on the roots of some plants.
Bacteria also carry out the process of denitrification (converting nitrogen compounds into nitrogen gas)
Nitrogen deposited into soil by fertilizers
Animals then take up the nitrogen from the plants and return it to the soil in urine and feces as well as death (decomposition).

24. The Nitrogen Cycle

25. The Water Cycle The water cycle is very dependent upon plants.
If plants are removed from the cycle many other nutrient cycles will be adversely affected.

26. The Water Cycle

27. The Carbon Cycle CO2 in atmosphere from:
Human activity
Volcanic activity
Respiration (breathing)
CO2 from oceans
Natural decomposition of organic material
It becomes fossil fuels which we burn, thereby putting carbon back into the cycle
Plants remove CO2 from both the atmosphere and oceans.
Carbon Cycle (2:55)

28. Carbon Cycle

29. Phosphorus Cycle
Phosphorus exists mainly in rock and soil minerals and in ocean sediments as phosphate.
Phosphorus found in the nucleic acids DNA and RNA
Aquatic: Phosphates dissolved by rain  phosphorus goes into bodies of water  organisms then consume the phosphorus
Terrestrial: Phosphorus is taken up by plants; animals then eat plants and obtain phosphorus
Rock, soil, phosphate

30. Phosphorus Cycle

31. Biodiversity
Biodiversity: The number of organisms living in an ecosystem and how common each species is; very important for the health of an ecosystem
Importance of Biodiversity (6:50)