Biodiversity (WJEC GCSE Biology)
Revision Note
Biodiversity
Biodiversity can be defined as:
The variety of living organisms present
The biodiversity of a habitat can be determined by assessing:
The number of different species present
A habitat with more species can be considered to have higher biodiversity
The number of individual organisms of each species present
A habitat with an even spread of numbers across all species is considered to be more biodiverse
The importance of biodiversity
Biodiversity is essential for the continued survival of living organisms, including humans
A habitat with high biodiversity is able to adapt to change
When many species are present the survival of any one species is not dependent on any other single species, but instead many species interact together
For example, for the food web below:
A decrease in the large lizard population, e.g. due to disease, would not result in starving fox and hawk populations, as these species have other food sources on which they can rely
A decrease in the fox population is unlikely to result in an explosion in kangaroo rats (and a resulting decrease in desert plants) because kangaroo rats have multiple predators
Biodiverse food web diagram
A food web that contains many species is resilient to change
The resilience that comes from biodiversity means that:
Food supply is plentiful
Food supply will be reliable for the future
There will be a reliable supply of biological resources, e.g. timber
Species that may be beneficial to humans, e.g. as medicines, will not go extinct before they are discovered
Humans can enjoy the well-being benefits of spending time in nature
Maintaining biodiversity
An increasing human population, and the accompanying demand for resources, means that global biodiversity is under threat
It is more important than ever to conserve the world's biodiversity; there are many ways in which humans are seeking to accomplish this:
Strategies for conserving biodiversity table
Strategy | Benefit to conservation |
|---|---|
Convention on International Trade in Endangered Species (CITES) | An agreement between governments that they will work to prevent the capture and sale of endangered plant and animal species |
Sites of Special Scientific Interest (SSSIs) and national parks | Protected areas within which human activities are regulated; this protects the species and ecosystems within their borders |
Captive breeding programmes | Zoos carry out carefully controlled breeding; this seeks to increase the numbers of individuals while maintaining the genetic health of populations The resulting offspring may remain in captivity as part of the breeding programme, or may be released into the wild |
Seed banks | Seeds of many plant species are stored under carefully controlled conditions; this means that plant species can be saved even if their natural habitats are lost |
Sperm banks | The sex cells of endangered animals may be stored in a similar way, protecting the genetic material of endangered species |
Local biodiversity action plans | These plans identify any at-risk species and lay out steps to ensure that they, and their habitats, are protected |
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