Introduction to
Ecosystems
2/13/12
What is a species?
 A group of individuals who have similar enough DNA
that they are able to produce viable offspring.
What is a population?
 Several individuals of the same
species that live in the same area.
What is a community?
 Populations that interact with one
another.
What is an ecosystem?
 An ecosystem a
community of biotic
(living) organisms
that interact with
abiotic (non-living)
organisms in an
interdependent
system.
What is a biome?
 A type of ecosystem that shares
similar climate, and components.
What are primary
producers?
 An Autotroph; A species that
creates its own food through
photosynthesis or from reduced
inorganic compounds.
What are consumers?
 Organisms that eat other organisms
to obtain energy.
What are decomposers?
 Organisms that obtain energy by
feeding on the dead remains of
other organisms or waste products.
 Get nutrients and live on dead organic matter
(habitat)
What is are trophic
levels?
 Trophic levels are organisms that obtain
their energy from the same source.
 Energy moves through ecosystems in the form of light,
or chemical energy.
 Usually no more than 4-5 trophic levels, due to 2nd law
of Thermodynamics.
What is an herbivore?
 An organism that eats plants.
What is an omnivore?
 An organism that eats plants and
animals.
What is a carnivore?
 An organism that eats other
animals.
What is a predator?
 An organism that kills and
consumes other organisms.
What is a prey?
 An organism that is consumed by a
predator.
What is the carrying
capacity of a population?
 When a population stabilizes at a maximum
number of individuals that can be supported by
resources available in the habitat over a sustained
period of time.
How does the carbon
cycle relate to the food
chain?
 Carbon (and other nutrients) move
up the food chain, carrying with it
stored energy.
What is parasitism?
 A long term relationship between two organisms that
is beneficial to one organism (the parasite), but
detrimental to the other (the host).
 (+/-)
 Example: Wasps that lay eggs in caterpillars, malaria
causing plasmodium, misquitos, Mycobacterium
(causes tuberculosis), lice, tapeworms
What is mutualism?
 A type of symbiotic relationship
between two species that is
beneficial to both species.
 (+/+)
 Examples: Bees and flowers, Treehoppers and ants,
Lichen = algae+fungus
What is commensalism?
 A relationship in which one
organism benefits and one the
other neither benefits or is
harmed by the interaction.
 (0/+)
 Barnacles on whales, Remora sharks hitch
a ride on larger sharks, clown fish and sea
anemones
What is amensalism?
 A relationship in which one
organism is harmed and the
other neither benefits or is
harmed.
 (0/-)
 Penecillin kills bread mold, humans
and cattle or sheep trample the grass,
Black walnut trees secrete chemicals
that kill other plants, redwoods have
tannic acid in their leaves/needles that
make the soil too acidic for other plants
to grow
What is
competition?
 A relationship in which both species
are negatively affect by the outcome
of the interaction.
 (-/-)
What is an ecological
niche?
 A specific role or job that an
individual has in an ecosystem.
What is a keystone
species?
 A species that has an exceptionally great impact on the
surrounding community.
 Pisaster (sea star), sea otter
Net Primary
Productivity
What is photosynthesis?
 A series of chemical reactions and electron transfer
events that converts the energy of light into chemical
energy stored in glucose.
 Equation for photosynthesis:
6CO2 + 6H20 + light energy  C6H12O6 +6O2
Why is dissolved oxygen
a measure of
productivity?
 Dissolved oxygen is produced in
photosynthesis.
 Dissolved oxygen is consumed in cellular
respiration.
What is gross primary
productivity?
 The amount of biomass produced by photosynthesis
per unit area over a specific time period.
What is Respiration?
 Metabolizing glucose (carbon compound) into
chemical energy using oxygen.
What is Net primary
productivity?
 The Net primary productivity= gross primary
productivity - respiration