Paradigms of biodiversity: an overview

Abstract

Biodiversity provides to the humankind enormous direct economic benefits and an array of indirect essential services through natural ecosystems. Biodiversity is essential for the ecosystem function and stability; several hypotheses are being tested for the relationship between biodiversity and ecosystem function. Biodiversity at the global scale is a balance between the rate of speciation and the rate of extinction. At a regional level it is a balance between the rates of immigration/invasion and that of local/regional extinction. The current rates of extinction are 1000-0000 times higher than the background rate of 10-7 species/species year inferred from fossil record. Today we seem to be losing two to five species per hour from tropical forests alone. This amounts to a loss of 16 m populations per year or 1800 populations per hour. Biodiversity is not uniformly distributed on the earth. There are broad global patterns, and regional and local concentrations of biodiversity. About 44% of vascular plants and 35% of vertebrates are concentrated as endemic species in 25 hotspots, which account for only 1.4% of the global land area. There are several theories to explain the nonuniform distribution of biodiversity. Biodiversity can be assessed at genetic, population, species, ecosystem and land-scape levels, at three spatial scales, viz. local. regional, and global. The strategies to conserve biodiversity include establishment of protected area network and corridors with emphasis on appropriate levels of management, reduction of anthropogenic pressure on natural populatior by cultivating them elsewhere, programmes of augmentation, reintroduction and introduction of target taxa, and in situ techniques such as establishing botanical and zoological gardens, and banks of rollen, seed, tissue culture, DNA, etc.