Biodiversity (Edexcel IGCSE Biology)
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Biodiversity
Biodiversity is defined as
the range and variety of different species of organisms on Earth, or within an ecosystem
It considers not only the species richness but the variation within each species, its distribution and population size
E.g. a high biodiversity would be found in an environment with lots of different species which show a lot of variation and are living in, all evenly distributed across the study area
Many human activities are reducing biodiversity in individual ecosystems and on a global level
E.g. waste production, deforestation and global warming
The importance of biodiversity
Different species depend on each other for:
Food
Shelter (eg. birds nesting in trees)
Maintenance of the physical environment (eg. tree roots provide stability for soils, ensuring they do not get washed away. This in turn provides a stable habitat for other plant species)
High biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for these three things
Populations with high levels of diversity are also more likely to be resilient to sudden environmental impacts or disease
Consider the food web below:
If the mouse population was suddenly wiped out, the fox and the hawk populations might decrease but would not be wiped out as mice are not their only food source
This example ecosystem has sufficient biodiversity to support the fox and hawk populations
The fox population can still depend on the rabbit and frog populations for food
The hawk population can still depend on the frog and sparrow populations for food
A food web demonstrates the importance of biodiversity within an ecosystem
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