Biodiversity:

Biodiversity is a measure of the variety of organisms present in different ecosystems.

The term “biodiversity” has been derived from 'bio' and ‘diversity’. Formerly it was called “natural diversity”.  “Diversity” means variety within a species and among species.

Importance of biodiversity and natural ecosystem:

Plants and animals (flora and fauna) diversity depends on the climate, altitude, soil, and the presence of other species. Biodiversity is not distributed evenly on Earth. It is richer in the tropics while there are fewer species in the polar regions. In the year 2006 large number of the Earth's species were classified as endangered or threatened species.

Examples:

1. Most of the hotspots are located in the tropics and most of the established species, are forests. For example, Brazil's Atlantic Forest contains' roughly 20,000 plant species, 1350 vertebrate species, and millions of insect species about half of which occur nowhere else in the world.
2. Biodiversity found on Earth today is the result of 4 billion years of evolution. The origin of life is not well known to science, though limited evidence suggests that until 600 million years ago, all life consisted of bacteria and similar single-celled organisms.
3. Biodiversity provides food for humans. A significant proportion of drugs are derived, directly or indirectly, from biological sources.
4. A wide range of industrial materials e.g. building materials, fibers, dyes, resins, gums, adhesives, rubber, and oil are derived directly from biological resources.
5. Biodiversity plays important role in making and maintaining ecosystems.
6. It plays a part in regulating the chemistry of our atmosphere and water supply.
7. Biodiversity is directly involved in recycling nutrients and providing fertile soils.