Definitions and scope of biodiversity

Summary

Biodiversity refers to the variability of life on Earth. It is commonly defined by biologists as the totality of genes, species, and ecosystems in a region, and it can be measured at multiple levels such as genetic variability, species diversity (including species richness), ecosystem diversity, and phylogenetic diversity. Although biodiversity is often used as an umbrella term, there is no single fixed definition; different organizations provide broad definitions, such as the FAO’s focus on variability among living organisms within and between species and the ecosystems they belong to, and the WHO’s emphasis on variability among living organisms from all sources. The scope of biodiversity extends beyond counting species. It includes how life is distributed across the planet (which varies greatly by latitude, climate, geography, and other factors), and it also covers how biodiversity changes over time, including major historical mass extinctions and more recent human-driven losses. Biodiversity is therefore treated as both a biological concept (genes–species–ecosystems) and a spatial-temporal one (distribution across regions and changes through geologic time and recent decades).

Key Points

• 1

  Biodiversity is the variability of life and is measured across genetic, species, ecosystem, and evolutionary (phylogenetic) levels.

• 2

  There is no single concrete definition of biodiversity; definitions vary, but commonly include genes, species, and ecosystems and the variability among living organisms.

• 3

  Biodiversity is unevenly distributed across Earth, with higher diversity often in the tropics and lower diversity toward polar regions, influenced by climate and geography.

• 4

  The scope of biodiversity includes both historical changes (e.g., mass extinctions) and ongoing human-driven biodiversity loss, which also reduces genetic diversity.