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Biodiversity is an all-encompassing word used to describe
the variety of life on Earth. Plants, animals, fungi and micro-organisms,
all form a part of biodiversity. Biodiversity refers not only
to diversity at the species level but also to the genetic
variation that contributes to the differences between individuals,
and, at the other end of the scale, to the combinations of
organisms, climate and geology that make up functioning ecosystems.
Without variety at the genetic level there would be no evolution.
Evolution acts on genetic diversity, selecting those genes,
and combinations of genes, that help to make a healthy organism
with good powers of reproduction.
Diversity at the species level is the product of evolution.
Different species result from the different combinations of
genetic material which give rise to varied characteristics.
These different combinations will be more or less ‘successful’
depending on the habitat.
A habitat includes both organisms and non-biological aspects,
such as climate and geology. Habitats vary through space,
between, for example, wet woodland, dry woodland, heathland,
grassland and lakes and rivers. Each habitat supports a particular
combination of species (plants, animals, fungi and other organisms)
which interact with one another and form a ‘community’.
There are many different types of interaction, for example,
competition for resources, predation and co-operation.
An ecosystem is a combination of habitats interacting on
a geographical scale. For example, a wet grassland may be
dependent on periodic flooding of a nearby river, or dunes
may form as a result of sand deposited by the sea.
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Defra define biodiversity in their introduction to
the ‘UK
Biodiversity Action Plan’ of 1994: ‘Biodiversity
encompasses the whole variety of life on Earth. It includes
all species of plants and animals, but also their genetic
variation, and the complex ecosystems of which they
are a part. It is not restricted to rare or threatened
species but includes the whole of the natural world
from the commonplace to the critically endangered.’
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