Our planet is home to millions of species of plants, animals and microbes. Each species has diverse characteristics and features. ‘Biodiversity’ was first coined by an eminent sociobiologist Edward Wilson in 1986. He defined biodiversity as the variation of life at all levels of biological organisation. Biodiversity is mainly studied at three levels: genetic diversity, species diversity and ecological diversity. Genetic diversity refers to genetic variations in a single species as well as between distinct species. Species diversity refers to the variety of species found in a particular geographical area. The last level is the ecological level, it refers to the difference between ecosystem types and the diversity of habitats within each ecosystem.
According to the IUCN, 2004, the total number of plant and animal species described on the earth so far is a little more than 1.5 million. But a more conservative and scientific estimate made by Robert May states that the global species diversity is about seven million. Nature's biological library is on fire and we are running out of time to index the titles of all the books in it. However, the taxonomical studies are more or less complete in the temperate regions compared to the tropical regions. According to recent species inventories, our biodiversity has some fascinating features. More than 70 per cent of all species recorded are animals, while plants comprise no more than 22 per cent. In animals, insects have the largest number of species and they constitute more than 70 per cent of the total.
On earth, the distribution of species diversity is uneven. The tropical regions are richer in species diversity, while the polar regions have fewer species. Considering the size of our country, which is 2.4 per cent of the world’s land area, it is a habitat to about 8.1 per cent of the global species diversity. India alone is home to about 45,000 plants and more than 90,000 animal species.
With such species richness, our country forms one of the 12 mega biodiversity countries of the world although many species are yet to be discovered and recorded. We need to preserve our rich biodiversity as it has taken millions of years of evolution to accumulate this wealth, which helps sustain our lives and the lives of other species with whom we share our planet.