BIODIVERSITY
Biodiversity is the biological variety and variability of life on Earth. It includes all
organisms, species and populations.
Types of biodiversity:
-genetic diversity
-species diversity
-ecosystem diversity
GENETIC DIVERSITY
It includes changes within the species at genetic level. Genetic
diversity is
the total number of genetic characteristics in the genetic makeup of a species. This
constitutes distinct population of the same species.
It takes place due to natural factors, human induced
differences etc.
SPECIES DIVERSITY
Species diversity is defined as the number of different
species present in an ecosystem and relative abundance of each of those
species.
-
Different types
of species can’t mate with each other.
-
Diversity occurs
at species level.
ECOSYSTEM
DIVERSITY
Ecosystem diversity deals with the variations in ecosystems within a geographical location and its overall impact on
human existence and the environment.
-
Diversity at
ecosystem level.
-
It includes
variation in ecosystem such as desert, tropical, rain forest etc.
PATTERNS OF
BIODIVERSITY
Latitudinal gradient
In general, species diversity
decreases as we move away from the equator towards the poles. With very few
exceptions, tropic harbours more species than temperate or polar areas.
-
Tropical
latitudes have remained undisturbed in the past, and thus has long evolutionary
time for species diversification.
-
Tropical areas
are less seasonal, constant and predictable.
-
There is more
solar energy available in the tropics, which contribute to higher productivity,
and in turn contribute to diversity.
SPECIES-AREA
RELATIONSHIPS
Species richness increases with
increase in explored area, but only upto a certain limit. If we plot a graph
between species richness for a wide variety of organisms, we obtain a
rectangular hyperbola.
Log S = log C + Z log A
Where,
S = species richness
A = area
Z = slope of the line
C = Y-intercept.
