1. Chapter 2 Principles of Ecology
2.1 Organisms and Their Relationships

2. What is ecology? Oikos Greek for “homestead” Ology means “study of”
Scientific study of interactions among organisms and their environment
Reveals relationships among living things (biotic) and nonliving (abiotic) parts of the world

3. What is ecology? Uses both quantitative and descriptive research
Combines information and techniques from many scientific fields:
Mathematics
Chemistry
Physics
Geology
And many others

4. Aspects of Ecological Study
Biosphere: portion of the Earth that supports life
High in atmosphere to bottom of ocean
Extends several kilometers above the Earth’s surface and several kilometers below the surface of the ocean
Comparable to peel of an apple
Very diverse climate

5. Living thing affected by:
Abiotic factors
Air currents
Temperature
Moisture
Light
Soil composition
Terrain
And many others

6. Living thing affected by:
Biotic factors
Same species for protection, competition, food, and reproduction
Other species for all but reproduction
Tree decay

7. Levels of Organization in Ecology
Need to study more than just an individual to get the whole story
Need to study relationships or interactions among organisms of the same and different species

8. Levels of Organization in Ecology
◊Biosphere
Biome
Ecosystem
Community
Population
- Organism

9. Populations
A group of organisms of one species that interbreed and live together in the same place at the same time

10. Populations
Compete with each other for food, water, space, light and other resources in short supply
How organisms share resources determines how far apart they live and how large a population gets

11. Populations
Some species reduce competition by larvae and adult stages living in different environments and using different resources as food (frogs and many insects)

12. Individuals Interact within Communities
Community: collection of interacting populations (all the populations at one place and time)
Change in one population will cause change in another population
Small changes
Large changes

13. Interactions among living things and abiotic factors
Ecosystem: interaction of populations in a community and nonliving (physical) surroundings
Three kinds of ecosystems
Terrestrial (land)
Fresh water
Marine: 75% of the earth

14. Organisms in Ecosystems
Habitat: place where an organism lives its life (home)

15. Organisms in Ecosystems
Niche: the role and position a species plays in its environment
All the interactions with abiotic and biotic factors
Everything the species does
How it uses resources
Its job

16. Organisms in Ecosystems
Even though two species occupy the same habitat, they do not occupy the same niche because resources (food, shelter) are used in different ways
It is an advantage for a species to occupy a different niche, unique strategies are important to reduce competition

17. Organisms in Ecosystems

18. Symbiosis
Permanent, close association between two or more organisms of different species
Three types of symbiosis
Commensalism
Mutualism
Parasitism

19. Commensalism
One species benefits, other species not harmed or benefited
Few examples because further study usually reveals mutualism or parasitism

20. Commensalism
Cattle egrets follow cattle to feed on the insects stirred up by the grazing cattle.
Egret benefits as it gets more food
Cattle is neither helped nor harmed

21. Commensalism Orchids growing on trees have a home and moisture
Orchids benefit while the tree is not affected

22. Mutualism
Both species benefit

23. Mutualism
A remarkable 3-way mutualism appears to have evolved between an ant, a butterfly caterpillar, and an acacia in the American southwest. The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar.
Research of Diane Wagner, American Museum of Natural History Southwestern Research Station

24. Mutualism
Ants “tending” soybean aphids

25. Parasitism
One organism benefits the other is harmed but usually not killed
Ticks
Ring Worm

26. Chapter 2 Principles of Ecology
2.2 Flow of Energy in an Ecosystem

27. How Organisms Obtain Energy
Ultimate source of energy is the sun
Producers use the sun’s energy to make food
Consumers eat producers and other consumers

28. How Organisms Obtain Energy
Autotrophs: “auto” = self; “troph”= energy
Most are photoautotrophs: organisms that use the sun’s energy to make food in the process of photosynthesis; all have chlorophyll
Some are chemoautotrophs; make food by using energy stored in chemical bonds (some Archaebacteria)

29. Photoautotrophs
Cyanobacteria
Plants
Algae

30. How Organisms Obtain Energy
Heterotrophs: “hetero”= other; “troph”= energy
Can’t make food so must feed on other organisms
Herbivores: only eat autotrophs
Carnivores: only eat other heterotrophs
Omnivore: eat both autotrophs and heterotrophs

31. How Organisms Obtain Energy
Heterotrophs: “hetero”= other; “troph”= energy, cont.
Scavengers: feed on dead (carrion and refuse)
Decomposers: breakdown and absorb nutrients from dead organisms (fungi, protozoans, many bacteria)

32. Heterotrophs
Carnivore
Decomposer
Scavenger
Herbivore

33. How Organisms Obtain Energy
Detritivores
Eat fragments of dead matter in an ecosystem, and return nutrients to the soil, air, and water where the nutrients can be reused by organisms.
Also considered heterotrophs

34. Matter and Energy Flow
Food Chains: simple model to show energy flow in an ecosystem; one possible route
Food web: several interconnected food chains
shows that an organism occupies more than one trophic level
Expresses more possible feeding relationships at each trophic level
More realistic than a food chain

35. Food Chain Arrows indicate direction energy flows
Usually 3 to 5 trophic (energy) levels
On average only 10% of energy is transferred to next trophic level
Most energy is lost as heat
Also lost as urine, feces and other

36. Food Chain
Top Carnivore
Carnivore
Omnivore
Herbivore
Producer

37. Food Web

38. Food Web Trophic level is one step in a food chain
Organisms can occupy more than one trophic level
Important part of organism’s niche is how it obtains energy

39. Energy and Trophic Levels
Energy Pyramid

40. Energy Pyramids Pyramid of Numbers
Count the number of organisms at each level
Numbers decrease as move up the pyramid
Not always reveals true relationship as one tree (producer) could support 50,000 insects (herbivore)

41. Energy Pyramids Pyramid of Biomass
Use dry weight of organisms at each level

42. Energy Pyramids
Pyramid of Numbers
Pyramid of Biomass

43. Chapter 2 Principles of Ecology
2.3 Cycling of Matter

44. Cycles in Nature Energy flows, nutrients cycle
Atoms of carbon, nitrogen and other elements in your body today made up the bodies of other organisms
Matter including nutrients are constantly recycled
The cycling of nutrients in the biosphere involves both matter in living organisms and physical processes found in the environment such as weathering.

46. Carbon Cycle

47. Nitrogen Cycle

48. Phosphorus Cycle

49. General Cycle