Al_baitu jamilatun

Al_baitu jamilatun
Al Baitu jamilatun

Friday, August 6, 2010

The magnitude of the study of Biodiversity

Objective Dasar Biodiversiti Negara yang ketiga adalahuntuk membekalkan sumber makanan kepada rakyat…
The current magnitude/ besarnya saiz kajian… of BiodiversityAn understanding of the magnitude of biodiversity at all levels is crucial to its conservation, management and utilization. The scale of biodiversity is immense, and while estimates of its magnitude are being improved, investment is required to bridge crucial knowledge gaps and synthesize existing information.The magnitude of biodiversity can be examined at scales ranging from the ecosystem and habitat, through the organismal, down to the genetic levelsSystem designed for use at the global level are of limited value at scales important for conservation purposesAs total site inventories are not available, ecological classification are an important component in the assessment of sites for conservation purposesOrganismal biodiversity can be assessed at different levels of the classification hierarchy from kingdoms ang phyla, through orders, families, genera, and species, right down to the infraspecific and generic levelDifferent uses of the category species , and the importance of phylogenetic divergence, mean that organism diversity cannot be measured objectively solely by differences in species number; the species, although the most commonly used unit of biodiversity, is not a standard unit of biodiversity measurementThe working figure of 1.75 million species is the current best estimate for the number of living ( non- fossil… species currently known to scienceAn estimated 90 % of described species have never been included in regional accounts of biotas, or in identification manuals or modern monographsThe described species represent only a small proportion of species on earth, and a working estimate of 13.6 million is adopted here as the overall total that exists; this suggests that only 13% of the species on earth have yet been describedMolecular and genetic studies demontratrate that there is enormous diversity at the infraspecific level in almost every examinedA high amount of genetic variability is found in most species. For animals, variability is on average greater within invertebrate than vertebrate species, which have more subdivided populations. For mollusks, amphians, reptiles and mammals, about 25-30% of this variation is due tu genetic difference between population, whereas for birds and insects which have higher gene flow between population, this figure is only 8-10%In plant species , there is a wider range of variability between difference species. Breeding system is the main determinant of the pattern genetic variability in plantsAn indication of the extent of genetic diversity present within a species can be obtained from domesticated organism; for example seven separate vegetables are derived from the single species Brassica oleracea, and more than 800 breeds of sheep derive from Ovis ariesHalaman 111 Buku Global biodiversity Assessment unep united nation environment programmeCambridge university pressExecutive editor v h HeywoodFirst publish 1995Isbn 0 521 56403 hardbackIsbn 0 521 56481 6 paperback

No comments: