BRAINCAKELoss of Biodiversity
Biodiversity is the variety of life in an area. It includes species diversity (the number of species and their relative abundance), genetic diversity (the variety of alleles within a species) and habitat diversity (the range of habitats).
Human activity reduces biodiversity at all three levels:
• Habitat loss and fragmentation: clearing forests, draining wetlands and building roads leave small, isolated patches that support fewer species and smaller populations.
• Agriculture: a monoculture replaces a mixed habitat with a single crop; removing hedgerows, spraying pesticides and herbicides, and fertiliser run-off causing eutrophication all reduce the number of species.
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Key terms in this lesson
- genetic drift
- A change in allele frequency in a population due to chance, with a greater effect in small populations.
- eutrophication
- The enrichment of water with mineral ions such as nitrate and phosphate, causing algal blooms and a fall in oxygen concentration.
More in Human Influence on Ecosystems
- Human Population Explosion
- Climate Change
- Depletion of Biological Resources
- The Burden of Proof
- Evaluating Studies
- Greenhouse Effect
- Evidence for the Global Temperature Increase
- Analysis of Ice Cores
All 29 lessons in Human Influence on Ecosystems · All Edexcel A-level Biology topics