1. Communities & Ecosystems
Our Wider World
Topic 5.1

2. Some new terms…
Species: a group of organisms that can interbreed and produce fertile offspring

3. What is not a species? Liger The liger is infertile.
Official information

4. Donkey + Horse = Mule
Mules are infertile. Are they a species?

5. Scientific names Genus species
Why give a species a scientific name if it already has a common name?

6. Habitat: The environment in which a species normally lives or the location of a living organism.

7. Population: A group of organisms of the same species who live in the same area at the same time.

8. Community: A group of populations living and interacting with each other in an area.

9. Ecosystem: a community and its abiotic environment.
Abiotic: “A” – not “biotic” – living

10. Abiotic Factors Abiotic factors may include Temperature Water Sunlight
Wind
Rocks and soil

11. Ecology: The study of relationships between living organisms and their environment.

12. Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances.

13. Heterotroph: an organism that obtains organic molecules from other organisms.

14. Consumer: an organism that ingests other organic matter that is living or recently killed.

15. Detritivore: An organism that ingests non-living organic matter.
Ex. Earthworms, Dung Flies

16. Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.

17. Decomposers Detritivores and saprotrophs are both decomposers
Decomposers are necessary as they eliminate waste that would otherwise pile up.
Decomposers recycle nutrients

18. Food Chain
A diagram which shows which organism eats which by using an arrow.
Only one feeding relationship is shown
Arrow indicates the direction energy flows
Grass  rabbit  wolf
Arrows must be in the proper direction for credit

19. The Ultimate Source of Energy for Most

20. A terrestrial food chain
Quaternary consumers
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
A terrestrial food chain
A marine food chain
Start with a producer
Continue with levels of consumers
Arrows:
A  B
A is being eaten by B
Why is this example unacceptable for IB?
Must include species names.

21. Grasslands Ecosystem Food Chain
Grass grasshoppers toad hognose snake hawk

22. Marine Ecosystem Food Chain
diatoms copepods herring seal great white shark

23. River Ecosystem Food Chain
Algae mayfly larva  juvenile trout kingfisher

24. Trophic Levels
Trophic Level: the position an organism has in its food chain.
Trophic Level T1
producer T2
primary consumer T3
secondary consumer T4
tertiary consumer T5
quaternary consumer

25. For a food chain to function…
In which trophic level would you want the largest number of organisms? (think, pair, share)

26. Food Web An interconnecting series of food chains
More diversity, complexity and a better representation of species interactions.
Direction of the arrow still indicates transfer of energy
You put the producer at the bottom of the diagram. The primary consumers fill in the next level, etc.

27. 5.1.8
Construct a food web containing up to 10 organisms, using appropriate information.
Phytoplankton is eaten by krill
Krill is eaten by squid, emperor penguins, crabeater seals, Adelie penguins, ice fish, tooth fish, and humpback whales
Squid is eaten by ice fish, tooth fish, crabeater seals, and emperor penguins
Ice fish and tooth fish are eaten by squid, crabeater seals, Adelie penguins, emperor penguins, petrel (bird) and humpback whale
Emperor penguins, crabeater seals, and Adelie penguins are eaten by leopard seals and killer whales.

30. Energy in Ecosystems
Light is the initial energy source for almost all communities.

31. In a food chain…
Energy originates from light, and is converted into chemical energy by producers. C

32. When that chemical energy (carbs, lipids, or protein) is digested, it passes from one trophic level to the next.
T1: Grass
T2: Horse
Energy Flow C

33. Energy Flow Thus, energy flows up the trophic levels. Trophic Level T5
quaternary consumer T4
tertiary consumer T3
secondary consumer T2
primary consumer T1
producer
Energy Flow

34. Chemical cycling (Chemical Energy flow)
Energy is lost at each trophic level in the form of heat loss during cell respiration
Microorganisms
and other
detritivores
Detritus
Primary producers
Primary consumers
Secondary
consumers
Tertiary consumers
Heat
Sun
Key
Chemical cycling (Chemical Energy flow)
Energy flow

35. Energy transformations are never 100% efficient.
Often only 10 – 20% of chemical energy in food is utilized.
Animals lose heat as they move around.
Warm-blooded animals use a lot of energy to heat their bodies.
Not all parts of a plant/animal are consumed

36. Pyramids of Energy 10 kJ m-2 y-1 100 kJ m-2 y-1 1,000 kJ m-2 y-1
T4: Tertiary
consumers
T3: Secondary
T2: Primary
T1:
producers
1,000,000 kJ m-2 y-1 of sunlight
10 kJ m-2 y-1
100 kJ m-2 y-1
1,000 kJ m-2 y-1
10,000 kJ m-2 y-1

37. Pyramid of Energy
Used to show how quickly and how much energy flows from one trophic level to the next in a community.
Shows rate and quantity
Units: kJ m-2 y-1

38. Pyramid of Energy
Since energy is lost at each trophic level, each level of the pyramid is smaller than before.
Organisms DO NOT CREATE energy, they simply TRANSFER it inefficiently.

39. Energy enters an ecosystem as light Energy exits as heat
Nutrients are recycled
Microorganisms
and other
detritivores
Detritus
Primary producers
Primary consumers
Secondary
consumers
Tertiary consumers
Heat
Sun
Key
Chemical cycling
Energy flow

40. Nutrient Recycling
Saphrotrophic bacteria and fungi (decomposers) recycle nutrients.
Nutrients from soil into tree
Nutrients are delivered back into soil
Tree dies. Decomposers release nutrients from storage in tree

42. Closed vs open system
The Earth is considered an open system for energy
The Earth is considered a closed system for matter