Biological Diversity and approaches
to its Conservation.
(Author: Mr. Samad Rojoa)
The world species diversity has been estimated to about 5 to 30 million species. Much discussion has been done on the state of our plant genetic resources and in creating awareness of their importance and need for conservation. There is no doubt. Both the Global 2000 report and the World Resources Institute conclude there is genetic resources losses.
Biological diversity is essential for the well being of the planet and the survival of humankind. Central to this is the diversity of plant and animal species which provide food, energy, fodder, fibre, medicines and other uses, upon which we depend for agricultural development and socio-economic welfare. An important component of the latter category is the genetic diversity within a given species which is vital for the continuation of evolutionary process. However, the world is confronted with accelerating loss of biodiversity at various levels: in the diversity of ecosystems, the diversity of species, and in the genetic diversity within species.
There is increasing awareness worldwide of the value, importance and fragility of biological diversity. Tropical forests are falling at a rate of just under 1% per annum, or 29 hectares per minute. A new study conservatively estimates that 34000 species of plants – 12.5% of the world’s flora – are facing extinction. At least one of every eight known plant species on earth is threatened. The 1993 Crucible Group concluded that we couldn’t conserve the world’s biological diversity unless we also nurture the human diversity that protects and develops it.
While the Convention on Biological Diversity emphasizes the in situ approach to conservation, it views both in situ and ex situ as complementary. An appropriate conservation strategy for a particular plant genepool requires a holistic approach. Selection of the appropriate method should be based on a range of criteria, including the biological nature of the species in question, practicability and feasibility of the particular method chosen, the cost-effectiveness and the security afforded by its application. Each technique of conservation has its own advantages and disadvantages. Complementary strategies, thus, enable sustainable conservation of a maximum range of genetic diversity in a given taxon
Within ex situ conservation, we have the choice between several methods, depending on the nature of the germplasm material. Wherever possible preference is given to the storage of orthodox seeds under low temperature and seed moisture content regimes, though it has been found that storage in liquid nitrogen (-196 °C) is more cost effective in the long term. For species producing recalcitrant seeds, the material can be stored as live plants in field genebanks. Other options are under in vitro conditions or as pollen. These two techniques do not generally allow germplasm to be conserved for long-term. However much research is actually being carried out to develop adequate methods for long-term conservation, especially for plants producing recalcitrant seeds. For the latter species, since they cannot be stored in seed form for long term, the conservation of pollen offers a possible alternative. However, in vitro culture is likely to be the key to effective ex situ conservation of many of these ‘problem’ species.
situ conservation offers the best option for conservation of tropical
plant genetic resources owing to the fact that several of these species
produce recalcitrant seeds. Studies are nowadays done towards the development
of new protocols for long-term conservation of plant genetic resources.