Communities & EcosystemsOur Wider WorldTopic 5.1
Some new terms…Species: a group of organisms
that can interbreed and produce fertile offspring
What is not a species?Liger
The liger is infertile.Official informationhttp://www.youtube.com/watch?v=CD6vpheUoPE
Donkey + Horse = MuleMules are infertile. Are they a
species?
Scientific namesGenus speciesWhy give a species a scientific
name if it already has a common name?
Habitat: The environment in which a species normally lives or the location of a living organism.
Population: A group of organisms of the same species who live in the same area at the same time.
Community: A group of populations living and interacting with each other in an area.
Ecosystem: a community and its abiotic environment.
Abiotic: “A” – not “biotic” – living
Abiotic FactorsAbiotic factors may include
◦Temperature◦Water◦Sunlight◦Wind◦Rocks and soil
Ecology: The study of relationships between living organisms and their environment.
Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances.
Heterotroph: an organism that obtains organic molecules from other organisms.
Consumer: an organism that ingests other organic matter that is living or recently killed.
Detritivore: An organism that ingests non-living organic matter.◦Ex. Earthworms, Dung Flies
Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.
DecomposersDetritivores and saprotrophs are
both decomposersDecomposers are necessary as
they eliminate waste that would otherwise pile up.
Decomposers recycle nutrients
Food ChainA 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
The Ultimate Source of Energy for Most
Food Chain
Start with a producer
Continue with levels of consumers
Arrows:A BA is being eaten by
B
Why is this example unacceptable for IB?
Must include species names.
Quaternary consumers
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
A terrestrial food chain A marine food chain
Grasslands Ecosystem Food Chain
Grass grasshoppers toad hognose snake hawk
Marine Ecosystem Food Chain
diatoms copepods herring seal great white shark
River Ecosystem Food Chain
Algae mayfly larva juvenile trout kingfisher
Trophic LevelsTrophic 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
For a food chain to function…
In which trophic level would you want the largest number of organisms? (think, pair, share)
Food WebAn interconnecting series of food
chainsMore 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.
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.
Energy in EcosystemsLight is the initial energy source
for almost all communities.
In a food chain…Energy originates from light, and
is converted into chemical energy by producers.
C
C
C
C
C
C
When that chemical energy (carbs, lipids, or protein) is digested, it passes from one trophic level to the next.
C
C
C
C
C
C
T1: Grass
T2: Horse
Energy
Flow
Energy FlowThus, energy flows up the trophic
levels.Trophic Level
T5 quaternary consumer
T4 tertiary consumer
T3 secondary consumer
T2 primary consumer
T1 producer
En
erg
y F
low
Energy FlowEnergy is lost at each trophic
level in the form of heat loss during cell respiration
Microorganismsand other
detritivores
Detritus
Primary producers
Primary consumers
Secondaryconsumers
Tertiary consumers
Heat
Sun
Key
Chemical cycling (Chemical Energy
flow)Energy flow
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
Pyramids of Energy
T4: Tertiaryconsumers
T3: SecondaryconsumersT2: PrimaryconsumersT1: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
Pyramid of EnergyUsed to show how quickly and
how much energy flows from one trophic level to the next in a community.
Shows rate and quantityUnits: kJ m-2 y-1
Pyramid of EnergySince 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.
Energy enters an ecosystem as lightEnergy exits as heatNutrients are recycled
Microorganismsand other
detritivores
Detritus
Primary producers
Primary consumers
Secondaryconsumers
Tertiary consumers
Heat
Sun
Key
Chemical cycling
Energy flow
Nutrient RecyclingSaphrotrophic bacteria and fungi (decomposers) recycle nutrients.
Nutrients
from soil
into tree
Tree dies. Decomposers
release nutrients
from storage in tree
Nutrients are
delivered back into
soil
Closed vs open systemThe Earth is considered an open
system for energyThe Earth is considered a closed
system for matter