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Biodiversity: what is it?
In its simplest form, biodiversity implies the richness and variety of biological
organisms (plants and animals). Ecologists, however, recognize three
different kinds of biodiversity: habitat diversity, genetic
diversity, and species diversity. In other words, biodiversity
refers to all the genes, species, and ecosystems present in a region.
Habitat diversity recognizes that different life forms are
found in distinct places, be they coral reefs, old growth forests
or savannahs. The disappearance, fragmentation, or destruction of
a habitat inevitably leads to the disappearance of the plant and
animal species supported by this habitat.
Genetic diversity refers to the degree of genetic variability
among populations of the same species. For example, sparrows in
the east coast comprise distinct populations from those in California.
While they could potentially interbreed (they are the same species
after all!), this rarely occurs (it is a long way to California),
so each population has its unique gene combinations. The more populations
of sparrows there are, the richer the genetic diversity. If only
one sparrow population were to exist, the genetic variability and
survivability of the species is likely to be very small. This is
a problem that exists among threatened animals and is of prime concern
when breeding zoo animals.
Species diversity relates to the variety of species found
in a region. It is estimated that between 50-90 percent of all species
are found in the tropical rainforests (most species, however, have
yet to be identified!). Unfortunately, tropical forests are being
destroyed at an alarming rate; some estimates claim that an area
the size of Pennsylvania is being cut down or burnt every year!
In addition to resulting in significant habitat loss, such destruction
will inevitably lead to huge species losses, perhaps as much as
half of all species will be lost within the next 75 years.
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