Principles of Ecology
Ecology: Study of the interactions
between
organisms and their environment.
Two types of things to look at:
Biotic: Living organisms
-Plants, Animals,
Bacteria
Abiotic: Non-Living things
-Rocks, Sun, Water,
Wind
Ecologists must choose what to study
-Organism: Study
of an individual
-Population: Group of organisms of one
species in the same area.
-Community: Group of populations in a given
area.
-Ecosystem: A community and all of the
abiotic factors around it.
-Biosphere: The
portion of the earth that supports life, including both biotic and abiotic
factors
Interactions between living and non-living
things
Habitat: The place where an organism lives.
-Niche: The role or position that an
organism has in its environment.
Symbiosis: Means
living together
3
types of Symbiosis:
-Mutualism: Both benefit
-Commensalism:
One benefits and other is neither helped nor harmed.
-Parasitism:
One benefits, other is harmed.
Nutrition and Energy Flow
The ultimate source of energy is the sun.
Organisms called AUTOTROPHS capture energy
from the sun and convert it into usable energy.
(Plants, some bacteria)
That useable energy is stored as different
types of sugars.
HETERTROPHS (animals) cannot capture energy
from the sun and must therefore eat autotrophs to get
energy.
Different
types of heterotrophs:
-Herbivores:
Plant eaters
-Carnivores:
Eat animals
-Omnivores:
Eat plants and animals.
-Scavengers
& decomposers: Eat dead organisms
Energy flow
l
A food chain
is a simple model to show how energy moves through an ecosystem.
l
A food web
shows all the possible eating relationships in a community.
l
Each organism in
a food web or chain represents a feeding step, or a “trophic level”.
l
Ecological
Pyramids show the relative amount of
energy at each trophic level in an ecosystem.
l
The base of the
pyramid represents the autotrophs (1st trophic level).
l
Higher trophic
levels are layered on top of one another.
l
Most but not all
ecological pyramids are large at the base and narrow at the top.
l
This is because
every time that an organism is eaten by the next trophic level, some of the
energy is lost as heat.