What Shapes an Ecosystem?
Abiotic and Biotic Factors,
Community Interactions
• Write “Updates to 90-93 and Food Web Notes”
on new page
– Record clarifying info about pages 90-93 (part 1 –
minimal notes)
– Takes notes on food webs (part 2)
– USE YOUR NOTES TODAY TO ANSWER
QUESTIONS!
The “niche”
• What is a niche?
– Full range of abiotic and biotic conditions in which
an organism lives – and how it uses these
conditions
– Biotic = living
– Abiotic = nonliving
Niche example
• Example: cane toad niche
– How the cane toad interacts with all biotic/abiotic factors –
for example:
• Bodies of water cane toads inhabit as tadpoles
• What shelter they use on land as adults
• The climate/type of ecosystem they survive in best
• How/when they reproduce
• What they eat and what eats them
• Etc…
• Note: no two species occupy the same exact niche! Brainstorm:
why not?
• Competition! One species wins, one loses (leaves the niche,
evolves, or goes extinct) eventually – might take time
Competition
• Could be competition for ANY type of resource
– Sun, water, food, space, nutrients, etc…
• What is it? What is an example in your ecosystem jar?
• Record ecosystem jar example
Predation
• Predation: An interaction in which one organism
captures and feeds on another organism.
• What is it? What is an example in your
ecosystem jar?
• Record ecosystem jar example
Symbiosis
• Symbiotic relationship
– A relationship in which two species live closely
together.
• 3 main classes of symbiosis – what are they?
– Mutualism
– Commensalism
– Parasitism
Mutualism
• What is it? What is an example in your
ecosystem jar?
• Mutualism: Win-Win
• Example: Shrew Loo
• Record ecosystem jar example
Commensalism
• What is it? What is an example in your
ecosystem jar?
• Commensalism: Win-neutral
• Example: Anemonefish
• Record ecosystem jar example
– Snails laying eggs on Elodea
Parasitism
• What is it? Is there an example in your ecosystem jar?
• Symbiosis – when one species benefits and other is
harmed – but not really predation (win-lose)
– Differs in that parasites often live in or on the host
• Example: Parasitic wasp
Food Webs (new notes!)
• Usually represent predation in an ecosystem
– Show how biomass & energy move in ecosystems
– Shows relationships between producers
(autotrophs) and consumers (heterotrophs)
• Why are they useful?
– Orcas and salmon – enough to support Orcas?
– Humans – enough food to support us?
– What if organism(s) are removed? Predictions…
– Easier than reading lots of papers (visual)
• Example food web – ecosystem jars!
– Build now – show organisms
Energy in food webs (in 3-2)
• Energy: ability to do work (NOT matter/material)
– Light energy (helps producers create food)
– Chemical energy (light converted to chem in food)
– Thermal energy (chem converted to “waste” heat)
• All energy begins at the producer level
– Can move its way up a food web
• Brainstorm – why do consumers have about 10% of the
energy available from organisms they consume?
• The remainder (90%) is:
– 1) kept by producers
– 2) lost as waste (thermal or chemical)
– All life processes produce chemical and thermal waste
– Show on food web now
Biomass in food webs (in 3-2)
• Biomass: living material in an ecosystem (in
grams, usually)
• All biomass begins at the producer level
– Moves its way up a food web
• Do consumers retain all biomass they
consume?
• No –Only about 10% gets to next level (rest is
kept or lost as waste – liquid, solid, gaseous)
– Show on food web now
Energy vs. Matter
• Energy is NOT matter
– Energy is stored in matter, can be released as
matter is broken down/metabolized
– Plants store energy by making glucose/food
– All organisms use/release energy by
consuming/breaking down food