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Community Structure and Dynamics
Ecology
DEFINITION
Study of interactions between organisms and their physical environment
HABITAT
An area where indivual lives
Source habitat
: reproduction>mortality
Sink habitat
: moratlity>reproduction
Microhabitat
Very small, localized area within a larger ecosystem
Usually
a number of microhabitats within a habitat
Ecological organization
:
Species/Population/Community/Ecosystem/Biome/Biosphere
COMMUNITY
Have
various sizes
, often form as a
product of coevolution
Have
adaptations
suited to the environmental conditions
Competition/ Predation/ Parasitism/
Commensalism/ Mutualism
Competition
occurs when two or more individuals attempt to use the same essential resource
Limited supply of resources when one individual decrease amount of resource available for others
INTERSPECIFIC
COMPETITION
Competitions among individuals within
different species
INTRASPECIFIC
COMPETITION
Competitions among individuals within
same species
COMPETITIVE EXCLUSION
PRINCIPLE
Two species having absolutely identical ecological niches cannot coexist
One species will be excluded by competition
If
overlap between two species decrease
,
coexistence
occurs
Position in the community:
Functional
: Species
play a role
e.g. predator, prey, decomposer etc.
Spatial
: Live in
a particular area
of community
Interaction of population of multiple species under a single environment
LIMITING RESOURCE
Any environmental resource that restrict the ecological niche of a species because they are scarce or unfavourable.
Exceeding tolerance of a species
Present in quantities smaller than required minimum amount
NICHE
Definition
Role of an organism
,
how it fits in environment, and local environment in which it lives
Represents
adaptations of species in environment, use of resources and lifestyle to which it is suited
By
Eugene Odum
in
The Fundamentals of Ecology (1959)
habitat is the organism's "address"
niche is its profession
Ecological Niche
Takes account of ALL BIOTIC and ABIOTIC aspects of organisms's existence
Distinctive lifestyle and role of an organism in a community
Realised niche
Resources of population
actually used
(REALISTIC)
As there is competition, predation etc, populations only use a subset of its functional niche
Fundamental niche
Resources of population
capable for use under ideal conditions
(THEORATICAL)
NICHE SPECIALISATION
