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Biodiversity: Biodiversity refers to measuring the biological parts of an ecosystem and measuring the
number and abundance of species in an area.
Species diversity: Species diversity refers to the variety of species per unit of area and it includes both
the number of species present and their relative abundance.
Habitat diversity: Refers to the range of different habitats in an ecosystem. It is associated with the
variety of ecological niches. For example woodland may contain rivers, soils, trees etc.
Genetic diversity: This refers to the range of genetic material present in a gene pool or population of a
species. Genes are sections of DNA found in the nucleus cells. A large gene pool leads to high genetic
Mechanism of natural selection
Charles Darwin was an explorer who has discovered the mechanism of natural selection. After having
been on an expedition to map the South American and Australian waters he was exposed to diverse
ecosystem's from which he noted that:
All species tend to over reproduce
Competition for limited resources
Species show variations
Darwin concluded that:
Those best adapted to their surroundings survive
These can then go on to reproduce
We now know that variation is caused by genetic diversity and that survival has a genetic basis- nature
selects individuals with what it takes to survive, so successful genes are selected and passed on to the
next generation. Over time, a change in the species gene pool takes place such as changes ultimately
lead to new species. "Survival of the fittest".
The role of isolation in forming new species
Geographical isolation forms new species because when areas are separated far away from each other
such as the islands of the Galapagos, there will be different ecosystem's present and with different
ecosystem's comes different species which are specifically adapted for those ecosystem. Without
geographical isolation, interbreeding would cause the genes from two populations to continue to mix
and characteristics of the ancestral species to remain.
The outer layer of the earth is divided into eight major and many minor plates. These plates come in
different shapes and sizes and can also move freely due to the liquid beneath them called
asthenosphere. This can cause earthquakes, volcanoes and mountain building. Movement of the tectonic
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Plate movement can also generate new diverse habitats thus promoting
biodiversity. An example of this can be seen between the Caribou and the Reindeer in Alaska and Serbia
which are spread far apart from each other and have given them different characteristics.…read more