1. Introduction to biodiversity
The importance of diversity
KEY CONCEPT → Biodiversity: a measure of the quantity of living (biological) diversity per unit area. It
includes species diversity, habitat diversity and genetic diversity
Biodiversity is influenced by:
- Climate: tropical regions with high - Altitude
productivity are more diverse than - Soil
polar regions - Geography
- Temperature and precipitation - Presence of other species
Habitat diversity → the number of ecological niches or range of different habitats that are present per
unit area of a biome, ecosystem or community.
- If habitat diversity is conserved, this usually leds to the conservation of both species and
genetic diversity
Species diversity → The variety of species per unit area. It includes both the number of species that are
present and their relative abundance
- Higher species diversity → greater ability to support different niches
- Measured in richness (number of species) or evenness (relative proportions)
Genetic diversity → The range of genetic material present in the population of a species or its gene
pool
- The gene pool is the number of variations of the same gene that are present in the DNA of a
particular species
- Large gene pool → healthy population with high genetic variability
- Small gene pool → low genetic diversity
Comparing communities
The Simpson Diversity Index can be used to compare two similar habitats and to monitor changes to
biodiversity over time
- Low D can indicate pollution, eutrophication or disturbances
- High D suggest a stable and mature site
Biodiversity hotspots
Biogeographic region that is both a significant reservoir of diversity and is under threatened
- 34 biodiversity hotspots that cover about 15% of the Earth’s surface
- E.g. West African Rainforest, Japan, California and Maditeranena coastline
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