Biological diversity, or bio-diversity for short, is the variety of life on earth-its genes, species, populations, andi?j?systems. Human actions that have degraded land. Bodies of fresh water, and the oceans have already caused bio-diversity to decline sharply, and even greater losses are expected if humanity continues its current unsestainable use of natural resources. In some cases potentially catastrophic, tolls on on the global environment, the loss of bio-diversity is the only truly irreversible consequence of environment degradation. When a gene, a species, a population, or an ecosystem is lost, it is gone forever.
When considering the loss of bio-diversity, species loss has become the most widely used measure. The subject of bio-diversity loss is, however, broader and more complex than this, because there is diversity at other levels of organization as well. For example, genetic diversity exists among members of an individual species, and a species can lose some of this diversity when local population are lost even though the species itself has not gone extinct. There is also diversity at higher levels, above the species level, in the genera ( the pluralof geneus), families, orders, classes, phyla, ecosystems, they are a part of. A loss of diversity, or in function, at any one of there levels may be independent of such losses at another level. For example, an ecoeystem may shrink dramatically in area and lose many of its functions, even though all of its constituent species may manage to survive.