Concept of biodiversity

The term 'biodiversity' was coined by Walter Rosen in 1986, and it captures the idea that every species is finely adapted to live within a specific environment, so that biodiversity's distribution pattern on Earth tracks the planet's climatic variation rather than being spread evenly. This shows up most clearly as a steep decline in species richness per unit area moving away from the equator: the Tundra and Taiga belts of northern Canada, Alaska, northern Europe and Russia support fewer than 12 tree species in total, the temperate forests of the United States hold 20-35 tree species, while the tropical forests of Panama pack in over 110 tree species within a comparatively small area. This single comparison already demonstrates the chapter's central organising idea — that biodiversity is not a fixed global constant …