Ecological Niche
Ecological niche
The ecological niche describes
the role an organism plays in
its environment. It consists of:
The species habitat.
The organisms activity, the
period of time it is active.
The resources it obtains from
the environment.
Eg. A pukeko lives in marsh
areas. It feeds of small insects
and grasses.
Fundamental niche and realised
niche
The fundamental niche
of a species includes the
total range of
environmental conditions
that are suitable for
existence without the
influence of interspecific
competition or
predation from other
species. The realized
niche describes that part
of the fundamental niche
actually occupied by the
species.
Niche differences
Organisms can be identified as either
– Generalists
Organisms with a broad niche
Eat lots of types of food
Live in many types of environments
Eg. house mice
– Specialists
Organisms with a narrow niche
Eat a narrow range of food items
Live in few, specific types of habitats
Eg. panda bear
Law of tolerance
The law of tolerance
states that for every
abiotic factor, an
organism has a range
of tolerance within
which it can survive.
Habitat
The habitat provides the
organism with the following
resources:
Mating sites
Food and water
Nesting sites
Shelter from climate extremes
Predator avoidance
Organisms may or may nit
have the adaptations to exploit
all the available resources
successfully.
What determines where species can
live?
All species have requirements for many
factors/conditions.
– Abiotic factors – non-living factors; ex.
temperature, precipitation, pH
– Biotic factors – other species; ex. prey
species, competing species
For each of these factors, species exhibit
a range of tolerance.
– For example, a fish species may only be
found within a pH range of 4.5 to 6 in lakes.
Competition
When two species use the same resources, they
are said to compete and their interaction =
competition.
– ex. lions and hyenas compete for food in Africa
Competition does not necessarily involve
contact; interaction may be only by means of
effects on the resources.
No two organisms can occupy exactly the
same niche at the same time