BIOLOGY
Aim: Ecology Intro
Class Notes
9-1
**Why is ecology important?
o Everything on Earth is connected. Understanding these connections
helps protect our environment.
A)
ECOLOGY
 Ecology is the study of interactions that take place between organisms and
their environment.
 Biosphere: portion of the Earth that supports living things (land, sea, air)
 Living things are affected by both living and non-living things
1—abiotic factors: nonliving parts of an environment;
examples: air, water, temperature
 Abiotic factors can determine which species surivive in
a particular environment
2—biotic factors: all the living organisms that inhabit an
environment; living things affect other living things
 In order to fully understand organisms, you must study all the other
organisms it interacts with.
B)
LEVELS OF ORGANIZATION
 Ecologists study organisms on different levels.
 Population: a group of organisms of the same species which interbreed
and live in the same area at the same time—members of the same
population may compete for resources
 Community: made up of interacting populations in a certain area at a
certain time—a change in one population in a community may cause change
in the other populations
 Ecosystem: interacting populations in a community and the community’s
abiotic factors
 Land—terrestrial
 Aquatic—marine and freshwater
C) ORGANISMS IN ECOSYSTEMS
o Habitat: the place where an organism lives—habitats can change
and even disappear
o Niche: all strategies and adaptations a species uses in its
environment—includes all interactions with the biotic and abiotic
parts of the habitat
o Example: when you look under a log, you may find many
different organisms each with its own niche, however, they are
sharing one habitat.
o it is an advantage for a species to occupy a niche different from
those of other species in the same habitat
o a species niche can change throughout its lifetime
o unique adaptations and structures are important to a species
niche because they reduce the competition within a habitat
D) SYMBIOSIS
o The close and permanent association between organisms of
different species
o There are three types of symbiotic relationships:
1—mutualism: both species benefit from the relationship
2—commensalism: one species benefits form the
relationship while the other is not affected
3—parasitism: one species benefits at the expense of the
other; the organism that benefits is called the host
while the organisms that is being harmed is called the
host