It is the variety and variation of
living forms that exists in an
ecological complex. The living form may
vary from plants, animal life and
micro-organisms. The plants may include
species of herbs to large trees and
animal life may vary from tiny insects
to huge mammals. There are three levels
at which biodiversity can be classified.
1. Ecosystem biodiversity: It consists of various habitats and the organisms living
under the different ecosystems. Hence it
is broader level of biodiversity and
determines the structure and function of
the particular ecosystem through
keystone species i.e. those species
which determine the ability of other
communities to exist in the ecosystem.
2. Species biodiversity: It takes into account different number of species of organisms that
exists in an ecosystem. It is measured
by two parameters.
(a). Species richness:
It is a number of species per unit area.
Larger is the area, higher will be the
species richness and greater will be the
(b). Evenness or Equitability:
It refers to the distribution of
organisms of various species at a
particular area. Let us take an example
of sample area 1 and sample area 2
having three species A, B & C each.
Sample area 1 has four organisms of
species A and 1 each of B & C. Similarly
sample area 2 has 2 organisms of A, B &
C. The evenness of sample area 2 is
greater as there is uniform distribution
of various organisms of any particular
species. More is the evenness, higher is
the species richness.
3. Genetic biodiversity: It is
the variation among the genes of
organisms of any species. It deals with
speciation i.e. evolution of new
species. It is a part of species
biodiversity but is considered to be a
complex level of biological diversity.