BIODIVERSITY AND ITS ORIGIN

BIODIVERSITY AND OUR LIFE

'Biodiversity' is the variation of life forms within a given ecosystem, biome, or on the entire Earth. Biodiversity is often used as a measure of the health of biological systems. The biodiversity found on Earth today consists of many millions of distinct biological species. The year 2010 has been declared as the International Year of Biodiversity.

'Biological diversity' or 'Biodiversity' can have many interpretations and it is most commonly used to replace the more clearly defined and long established terms, species richness and species diversity. Biologists most often define biodiversity as the 'totality of genes, species, and ecosystem of a region.' An advantage of this definition is that it seems to describe most circumstances and present a unified view of the traditional three levels at which biological variety has been identified:

• Species diversity
• Ecosystem diversity
• Genetic diversity

But professor Anthony Campbell at Cardiff University has defined a fourth, and critical one, known as 'Molecular Diversity'. This multi-level conception is consistent with the early use of biological diversity in the late 1960s through 1970s by Raymond F. Dasmann who apparently coined the term and Thomas E. Lovejoy who introduced it to the wider conservation and science communities. An explicit definition consistent with this interpretation was first given in a paper by Bruce A. Wilcox commissioned by the International Union for the Conservation of Nature and Natural Resources for the National Parts Conference in Bol. Wilcox's definition was 'Biological diversity is the variety of life forms at all levels of biological system {i.e. Molecular, organic, population, species and ecosystem}. Subsequently, the 1992 United Nations' Earth summit in Rio de Jeneiro defined biological biodiversity 'as the variability among living organisms from all sources including , interalia, terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part. This includes diversity within species. Between species and of ecosystems'. This definition is used in the United Nations' convention on Biological Diversity.

One of the text-book definition is 'variation of life at all levels of biological organization'. For geneticists, biodiversity is the diversity of genes and organisms. They study processe such as mutuations, gene-transfer, and genome dynamics that generate evolution. Consistent wit this, Wilcox also stated genes are the ultimate source of biological organization at all the level of biological systems.

New species are regularly discovered {an average between 5-10,000 new species each year,, most of them insects} and many, through discovered, are not yet classified {estimates are that nearly 90% of all anthropods are not yet classified}. Most of the terrestrial diversity is found in tropical forest.

Biodiversity is not uniform across the Earth. In terrestrial habitats, for example tropical regions are typically rich where as polar region support fewer species. Rapid enviromental changes typically cause extinctions. 99.9% of species that have existed on Earth are now extinct. Since life began on Earth, five major mass extinctions have led to large and sudden drops in earthly biodiversity. The phanerozoiceon {the last 540 million years} marked a rapid growth in biodiversity in the Cambrian explosion- a period during which nearly ever phylum of multicellula organisms first appeared. The next 400 million years was distinguished by periodic massive biodiversity loses classified as mass extinction events. The Permo-Triassic extinction, 250 million years ago was the worst, devastating life in the saea and on land; vertebrate recovery took 30 million years. The most recent, the Cretaceous-Textiary extinction event, occured 65 million years ago and has attracted more attention than all others because it killed the nonavian dinosaurs.

The period since the emergence of humans has displayed an ongoing reduction in biodiversity.Named the Holocene extinction, the reduction is caused primarily by human impacts, particularly the desruction of plant and animal habitat. In addition, human practices have caused a loss of genetic diversity. Biodiversity's impact on human health is a major international issue.

ETYMOLOGY

The term was used first by wildlife scientist and conservationist Raymond F. Dasmann in the 1968 lay book. A different kind of country advocating conservation. The term was widely adopted only after more than a decade, when in the 1980s it came into common usage in science and environmental policy. Use of the term by Thomas Love Joy, in the foreword to the book Conservation Biology. Introduced the term to the scientific community. Until then the term 'natural diversity' was common which was introduced by the Science Division of Nature Conservancy in an important study, 'The Preservation of Natural Diversity'. By the early 1980s the T.N.C.'s science program and its head, Robert E. Jenkins, Lovejoy and other leading conservation scientists at the time in America advocated the use of the term, 'Biological Diversity'.

The terms contracted from biodiversity may have been coined by W.G. Rosen in 1985 while planning the National forum on Biological diversity organized by the National Research Council {N.R.C.} which was to be held in 1986 and first appeared in a publication in 1988 when the endomologist E.O. Wilson used it as the title of the proceeings of that forum.

Since this period, both the term and the concept have achieved widespread use among biologists, enviromentalists, political leaders, and concerned citizens. The term is sometimes used to reflect concern for the natural environment and nature conservation. This due has coincided with the expansion of concern over extinction observed in the last decades of the 20^th century.

A similar concept in use in the United States is 'natural heritage'. Less scientific, it predates the other and is more accepted by the wider audience interested in conservation. It includes geology and landforms and is commonly known as 'Geodiversity'.

LINKING BIODIVERSITY LEVELS

A complex relationship exists among the different diversity levels. Identifying one level of diversity in a group of organisms doesn't necessarily indicate its relationship with other types of diversities. All the types of diversity are broadly linked and a numerical study investigating the link between tetrapods. Taxonomic and ecological diversity shows a very close co-relation between the two.