Download Ecology Notes 4-2

Ecology Notes 4-2
Community Interactions
Biotic vs. Abiotic
Biotic factors – living factors in an
environment. Ex. Trees, birds, bacteria,
etc.
 Abiotic factors – non living factors in an
environment. Ex. Temp., rainfall, humidity,
soil.

Niche

Niche – full range of conditions in which
an organism lives (biotic and abiotic). It is
like your “occupation”.
Competition
Competition – occurs when
organisms attempt to use a
resource (water, nutrients,
light, food or space) at the
same time.
 We call this a +/- relationship.
 Competitive Exclusion
Principle – no two organisms
can occupy exactly the same
niche in the same habitat at
the same time.

Predation

One organism
captures and feeds
on another organism.

This is a +/relationship.


Symbiosis – any relationship
where two organisms live
closely together.
3 types of Symbiosis
1. Mutualism +/+ both
organisms benefit. Ex.
Flowers/insects.

2. Commensalism +/0 one organism
benefits and the other is neither helped
nor harmed. Ex. Whales/barnacles

3. Parasitism +/- One organism lives
on or in another organism. Ex. Dog/flea