Habitat and Niche
Habitat
Type of environment in which a population or
species regularly lives.
Includes abiotic and biotic factors
Examples of vegetative habitats
Forest, meadow, pasture, coniferous forest, etc.
Habitats
Habitats can be subdivided into layers or
zones
Microhabitats
Forest canopy: leaves, branches
Shrub layer: leaves, branches, trunks
Herb layer:
leaves, stems, mosses, ferns
Litter:
dead fallen leaves, logs,
Varies in depth, quality
Soil: topsoil, subsoil
Occupying Space
A species may occupy a specific part of a
microhabitat
The limitations are often very distinct
Example
Hypogymnia imshaugii
(a tube lichen)
Lives on the upper part of
branches of certain tree
species
Limited to a certain
latitude
Limited by rainfall and
humidity
Example 2
Western Rivers
Rainbow trout can be found in
highly oxygenated, faster-moving
water and feeding on specific
insects
High concentration
of dissolved oxygen
Mountain whitefish can be found
in less oxygenated, slowermoving water and feeding on
different insects
Low concentration
of dissolved oxygen
Fast current
Slow current
Niche
(Pronounced “neesh”, but “nitch” is OK)
Species’ or population’s role in its community
Characteristics of a niche:
Habitat & microhabitat (Space occupied)
Food “spectrum,” essential nutrients
Reproductive requirements
Nutrition, nest/den sites
Seasonality: When are resources required, used.
Climate requirements: Humidity, rainfall, sunlight
Niche Example
Oregon little brown bat (Myotis lucifugus)
Sleeping / reproduction space: rock crevices, caves,
dense trees near water
Seasonality / temporal aspects: Actively feeds at night –
hibernates during the winter months
Diet: Insectivore – prefer insects with aquatic life stages
Range: Temperate coniferous forests
Another species of bat may have a similar niche, but
not exactly the same
Two kinds of niche
Fundamental niche
All of the potential niche components for a given
species if there were no competition for those
resources
Realized niche
What the population actually gets while in
competition with other species
Niche diagram
Here are niches for two species before competing
for two resources
Fundamental niches
Niche diagram
When the two species actually compete, there may
be some overlap…
Realized niches
overlap leads to competition
Niche
No two species can occupy the same niche
at the same time without intense competition
one species will be removed
Vacant niche: a niche that is not occupied by
a species (not all scientists agree that this is
real)
example: rainbow trout in eastern Oregon have no
gill parasites like some other fish – is this a vacant
niche for some parasitic organism?
Competition
Organisms continuously compete for
resources (space, food, mates, etc)
Intraspecies competition: competition between
organisms of a different species
ie- bats and birds competing for a species of insect
Interspecies competition; competition between
individuals of the same species
ie- two bats competing for a swarm of mosquitoes
Competition
Competition drives natural selection
Co-evolution: in a natural setting, species continuously compete
and evolve with each other and the evolutionary change or one is
based on the evolutionary change of another
Humans and our parasites
Forest trees and fungi
Invasive species are successful because they have not coevolved with the native species and can take over their niche
New diseases
Invasive plants
Invasive insects
Rabbits in New Zealand
Reducing competition
Different species often
partition resources to
reduce intraspecies
competition
Different species of
birds will occupy
different areas within
the canopy of a tree to
reduce competition
from other species