Ecology Notes 4-2
Biotic vs. Abiotic
Biotic factors – living factors in an
environment. Ex. Trees, birds, bacteria,
Abiotic factors – non living factors in an
environment. Ex. Temp., rainfall,
Niche – full range of conditions in which
an organism lives (biotic and abiotic). It is
like your “occupation”.
Competition – occurs when
organisms attempt to use a
resource (water, nutrients,
light, food or space) at the
We call this a +/- relationship.
Principle – no two organisms
can occupy exactly the same
niche in the same habitat at
the same time.
captures and feeds
on another organism.
This is a +/-
Symbiosis – any relationship
where two organisms live
3 types of Symbiosis
1. Mutualism +/+ both
organisms benefit. Ex.
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