The term BIODIVERSITY was first coined by the entomologist E.O. Wilson in 1986. Biodiversity is the heritage of 3 billion of years of evolution. Diversity is a basic property of life. The striking feature of Earth is the existence of Life and the striking feature of Life is its Diversity. Biodiversity is the measure of the number, variety and variability of living organisms. Variety refers to the number of different types of organisms. Quantity is the number or total biomass of any one type. Distribution is the extent and nature of geographic spread of different types of organisms.Biodiversity includes diversity within species, between species and among ecosystems. Biodiversity is the sum of life on earth and includes genetic, species and functional diversity. The status and trends in biodiversity reflect the health of the ecosystems that support and enrich human life.
Biodiversity – plants, animals, microorganisms and the ecological processes that interconnect them – forms the planet’s natural productivity. In the last 50 years, there was “a substantial and largely irreversible loss in the diversity of life on Earth” (Millennium Ecosystem Assessment, 2005).Human activities have altered the world’s terrestrial, freshwater and marine ecosystems throughout history.
Types of biodiversityGenetic diversity – the genetic variation among individuals in a species
Species diversity – the number of different species in a given area
Ecosystem diversity – the variety of ecosystems on Earth /the variety of interactions among organisms in a community
The biodiversity is the spectrum of life on earth, in terms of variation in genes, populations, species, ecosystems, and interactions among them. Most estimates of the total number of species on Earth lie between 5 million and 30 million. Of this total, roughly 2 million species have been formally described; the remainder are unknown or unnamed. Biodiversity is not static, but constantly changing. Biodiversity is increased by genetic change and evolutionary processes and reduced by processes such as habitat degradation, population decline, and extinction.
It is the variation within genes(alleles & haplotypes ),variation within individuals(individual heterozygosity), variation within populations(allele frequencies, average heterozygosity, average number of polymorphic alleles and loci) and variation among populations (differentiation and genetic distance).
It represents the different types of plants, animals and other life forms within a region. It is a dynamic property and changes over space and time. The number of species and their relative abundances depend on the size and geographic area of the ecosystem. Species diversity is an indicator of the biological richness/stress of an ecosystem.
It is the variety of different habitats/ecosystems in a particular area ( e.g.. wetland, woodland, grassland). The ecosystems of the world are maintained by their biodiversity. Every ecosystem can be characterized by its own species composition. The ecosystems differ in features such as physical structure, temperature, water availability and food types.
Why is biodiversity important?
- Regulation of climate and biogeochemical cycles,
- Hydrological functions
- Soil protection,
- Crop pollination,
- Pest control,
- Recreation and ecotourism
- Wildlife habitat and diversity
- “public goods” to society
Values of biodiversity
Ecological values - all living creatures are supported by the interactions among organisms and ecosystems. Loss of biodiversity makes ecosystems less stable, more vulnerable to extreme events, and weakens its natural cycles.
Economic values -A biologically diverse natural environment provides humans with the necessities of life and forms the basis for the economy. Every thing we buy and sell originates from the natural world.
Cultural values - Human cultures around the world profoundly reflect our visceral attachment to the natural world. Thus cultural diversity is linked to Earth’s biodiversity.
Biodiversity and Sustainability
The biodiversity of an ecosystem contributes to the sustainability of that ecosystem. Higher/more biodiversity is more sustainable. Lower/less biodiversity is less sustainable. High biodiversity in an ecosystem means that there is a great variety of genes and species in that ecosystem.
Conservation of biodiversity
Ex-situ conservation means “off-site” conservation.The species of plants and animals to be protected are removed from the natural habitats and are placed in the safer areas under the control of man. Botanical gardens, zoos and the arboreta are the traditional methods of ex-situ conservation. Germ plasm banks or Seed banks (also Gene banks) are some other methods of ex-situ conservation.
In-situ conservation means “on-site” conservation.It is the protection of species within the natural habitat of the species of animals and plants. It includes protection in the wildlife sanctuaries, national parks and biosphere reserves etc. that have been formed to protect threatened and even rare species. In India we have 608 protected areas: 95 national parks, 13 biosphere reserves and 500 wildlife sanctuaries. In India, there are four internationally recognized Biosphere Reserves: Nilgiri, Gulf of Mannar, Sunderbans and Nanda Devi (Man and Biosphere Programme of UNESCO). In Tamil nadu ther are 5 national parks, 20 wild life sancturies and 2 biosphere reserves.
“Every country has three forms of wealth: material, cultural and biological. The first two we understand well, because they are the substance of our everyday lives. The essence of the biodiversity problem is that biological wealth is taken much less seriously. . . ..” - Edward Wilson, The Diversity of Life (1992).