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Chapter 2: Living Things in Ecosystems
Section 2.2 – How Species
Interact With Each Other
Section 2.3 – Adapting to the
Environment
Ecosystems are made up of abiotic
and biotic factors; as well, biotic
components can affect each other
in various relationships.
Predation
In predation, one organism kills and eats
another.
The organism that is eaten
is called the prey, and the
one that does the eating is
called the predator.
Predators tend to feed on young and
weak individuals and often limit the
size of the prey population.
As populations of prey begin to
decline, the predators either
switch food sources or die off
themselves.
COMPETITION
Competition
occurs when two
or more organisms
of the same or
different species
attempt to use the
same limited
resource.
Species can compete even if
they never come into contact
with each other.
PARASITISM
Parasitism is when
an organism lives in
or on another
organism and
feeding on it
without
immediately killing
it.
Parasites are the organisms
which do the feeding, while
the host is the organism
being fed off.
Mutualism
Mutualism is the
cooperative
partnership
between two
species in which
both species
benefits.
Commensalism
Commensalism is the relationship in
which one species benefits and the
other is neither helped nor harmed.
Organisms tend to be well
suited for their environment.
Kangaroo rats are well suited to the
deserts of southwestern U.S. –
where there is very little water
• Eliminate very little
water in their feces
and urine.
• They do not sweat.
• Their active at night,
when it is cooler.
How does this close match
between organisms and their
environment come about?
Darwin described this close
relationship as Natural
Selection.
Darwin proposed that
over may generations
natural selection causes
the characteristics of
populations to change.
This change is known
as evolution.
With each generation, an
organism develops better
adaptations – inherited traits that
increases an organisms chance of
survival.