2. Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Ecology
The study of the relationships between living organisms and their interactions with the environment

3. Ecologist at Work

5. Levels of Organization
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Levels of Organization
Levels increase in complexity as the numbers and interactions between organisms increase.
organism
population
biological community
ecosystem
biome
biosphere

6. Organism: The most basic level of organization in an ecosystem.
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Organism: The most basic level of organization in an ecosystem.
Example: Wolf

7. Population : Organisms of one species that share the same geographic location
Example: Wolf Pack

8. Biological community: a group of interacting populations that live in the same geographic area at the same time
Example: Wolf Pack and Caribou

9. Ecosystem: a community and all of the abiotic factors that affect it
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Ecosystem: a community and all of the abiotic factors that affect it

10. Abiotic Factors: Nonliving factors in an environment
Organisms adapt to survive in the abiotic factors present in their natural environment
Biotic Factors: Living factors in an environment

11. Examples of Biotic and Abiotic Factors

12. Biome: a large group of ecosystems that share the same climate and have similar types of communities.

13. A thin layer around Earth
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
The Biosphere
A thin layer around Earth
Extends several kilometers above the Earth’s surface
Extends several kilometers below the ocean’s surface

14. Biosphere

15. The Biosphere 2.1 Organisms and Their Relationships Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
The Biosphere

16. Ecosystem Interactions
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Ecosystem Interactions
A habitat is an area where an organism lives.
A niche is the role or position that an organism has in its environment.

17. Alaskan Wolf Habitat

18. Alaskan Wolf Niche
Keeps caribou population healthy

19. Community Interactions
Competition: when more than one organism uses resources at the same time
Examples:

20. Predation: the act of one organism consuming another organism for food
Predators: hunters
Prey: the hunted

21. Predator-Prey Relationship

22. Almost every species is food for another species
Predators (hunters) and prey (the hunted) have (in most cases) existed together for years

23. Predators have evolved into efficient killing machines (talons, canines, claws)
Prey have evolved very effective defenses (smell, hearing, camouflage)
The predator population is closely linked to the prey population

24. Symbiotic Relationships
Chapter 2
Principles of Ecology
2.1 Organisms and Their Relationships
Symbiotic Relationships
Relationship that exists when two or more species live together
Mutualism
Commensalism
Parasitism

25. Mutualism
Two or more organisms that live closely together and benefit from each other
Example: Lichens—a relationship between algae and fungi
Algae provides food for the fungi, and the fungi provides habitat for the algae

26. Lichen

27. Commensalism
One organism benefits from the relationship, the other is unaffected by it
Example: anemone fish and sea anemones

28. Ex. Barnacles and a sea scallop

29. Parasitism One organism benefits at the expense of the other
Ex. Sea lamprey and fish

30. Section 2.2 Energy Flow in an Ecosystem

31. Also called primary producers
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Energy in an Ecosystem
Autotrophs
Organisms that collect energy from sunlight or inorganic substances to produce food
Also called primary producers
A lynx is a heterotroph.

32. Examples of Autotrophs

33. Heterotrophs: organisms that gain energy from consuming other organisms
Also called consumers

34. Types of Heterotrophs:
Herbivores: eat autotrophs (plants)

35. Carnivores: eat other heterotrophs (animals)

36. Omnivores: eat autotrophs and heterotrophs (plants and animals)

37. Detritivores eat fragments of dead matter in an
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
ecosystem, and
return nutrients
to it.
Detritivores eat fragments of dead matter in an
Fungus

38. Trophic level: Each step in a food chain or food web
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Models of Energy Flow
Food chains and food webs model the energy flow through an ecosystem.
Trophic level: Each step in a food chain or food web

39. Food chain: model that shows how energy flows through an ecosystem.
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Food Chains
Food chain: model that shows how energy flows through an ecosystem.

40. Notice that the arrows point in the direction of the energy flow, NOT which organism eats which!
The original source of energy is the sun
Sun → Corn → Pheasant → Fox

41. There may be more than one level of consumer in a food chain
Ex. Grass → grasshopper → toad → snake → hawk
Producer → primary consumer (herbivore)→ secondary consumer (carnivore) → tertiary consumer (omnivore)

42. Food web: model representing the many interconnected food chains
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Food Webs
Food web: model representing the many interconnected food chains

43. Food Web Consists of two or more interacting food chains
Most food chains are part of a food web

44. Chapter 2
Principles of Ecology

45. Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Ecological Pyramids
A diagram that can show the relative amounts of energy, biomass, or numbers of organisms at each trophic level in an ecosystem

46. Pyramid of Energy (Energy Chain)

47. The size of the boxes indicate the relative amount of energy available
The lower levels limit the upper levels
Available energy decreases as you move up the levels

48. Energy never “cycles,” it dissipates into the system (used for life processes and given off as heat and used for storage)
Only 10% of the energy available at one trophic level can be used by the consumers at the next level

49. If the first level of the energy pyramid (the producers) provide 1,000J of energy, how much is available to the second trophic level?
100J

50. How much energy is available for the third level?
10J
The fourth? 1J

51. Pyramid of Biomass

52. Pyramid of Biomass
The total amount of biological matter (tissue) in a community or population
Notice it takes many producers to support one shark
The lower levels limit the upper trophic levels

53. Pyramid of Numbers

54. Cycles in the Biosphere
Chapter 2
Principles of Ecology
2.3 Cycling of Matter
Cycles in the Biosphere
Energy is transformed into usable forms to support the functions of an ecosystem.
The cycling of nutrients in the biosphere involves both matter in living organisms and physical processes.

55. Chapter 2
Principles of Ecology

56. Chapter 2
Principles of Ecology

57. Chapter 2
Principles of Ecology