Population Ecology &
Symbiosis Notes
Population Ecology
Ecologist study how populations change based on interactions within the environment. By
graphing populations, scientist can explain relationships between organisms.
Predator vs. Prey
Predator- an organism that hunts or eats another organism
Prey- the organisms that is eaten or hunted.
Competition- when 2 or more individuals or populations try to
use the same limited resource
Habitat vs. Niche
-An organism’s habitat is
the part of an ecosystem in
which the animal lives.
Carrying capacity- the maximum number of
organisms that the environment can hold
Limiting factors- conditions or resources in an
environment that can control the population in an
environment.
- An organism’s niche is
the role an organisms plays
in an ecosystem.
Symbiosis in an Ecosystem
Some species have a very close interaction with other
species
•Symbiosis- a close long-term relationship between two
or more species
•Individuals in a symbiotic relationship can benefit
from, be unaffected by, or be harmed by the relationship
Three types of Symbiotic Relationships
1) Mutualism
2) Commensalism
3) Parasitism
Mutualism
A symbiotic relationship in which both organisms benefit.
Ex: Bacterial living in your intestine
The bacteria get a plentiful food supply from you and in return you
get vitamins from the bacteria produced
Commensalism
A symbiotic relationship in which one organisms benefits and the
other is unaffected.
Ex: Sharks and remora
Parasitism
A symbiotic relationship in which one organism benefits while the
other is harmed
Ex: tapeworm and human, tomato hornworm and wasps
Mutualism
Commensalism
+/+
+/0
Parasitism
+/-
Both organisms benefit
One organisms benefits, other
unharmed
One organism benefits, other
is harmed