Biodiversity Within a Community (AQA AS Biology): Revision Note

Biodiversity

• Biodiversity can be thought of as the variation that exists within and between all forms of life

• Biodiversity looks at the range and variety of genes, species and habitats within a particular region

• It can be assessed on different scales

  • The number and range of different ecosystems and habitats on Earth

  • The number of species and their relative abundance within a small, local habitat (like a pond)

• Biodiversity is essential for the resilience of ecosystems, in that it allows them to resist changes in the environment

Ecosystem or habitat diversity

• Ecosystem diversity refers to the variety of different ecosystems or habitats within a particular area or region

• Each ecosystem provides unique environmental conditions, supporting different communities of organisms

• An area with a large number of distinct habitats (e.g. forests, wetlands, grasslands) has high ecosystem diversity and therefore greater overall biodiversity

  • E.g. A coral reef is a highly diverse ecosystem — it contains a range of microhabitats and ecological niches, supporting a wide variety of species

• In contrast, environments with limited habitat types, such as sandy deserts, have low ecosystem diversity. The relatively uniform conditions support fewer species, resulting in lower overall biodiversity