By Dr. Sandip Pal (Asst. Professor, Department Of Zoology, Barrackpore Rastraguru Surendranath College)
What is Biodiversity?
Biodiversity refers to the variety of life forms on earth including the different plants, animals, micro-organisms, the genes they contain and the community or ecosystem they form. It is considered at three main levels such as species diversity, genetic diversity and ecosystem diversity. Relative to the variety of habitats, biotic communities and ecological processes in the biosphere, biodiversity is vital in a number of ways including maintenance of the integrity of the environment through maintaining CO2-O2 balance, regulation of biochemical cycles, absorption and breakdown of pollutants and waste materials through decomposition and many more.
Despite the benefits from biodiversity, today’s threats to species and ecosystems are the greatest recorded in recent history and virtually all of them are caused by human mismanagement of biological resources. The main threats to biodiversity include loss, fragmentation and degradation of habitat, the spread of invasive species, unsustainable use of natural resources or overexploitation, climate change, and pollution. It is important to conserve biodiversity to maintain the integrity of natural ecosystems and human should conserve it because of their own benefits which are essential to live our life on earth.
Conservation of existing biodiversity
Conservation is a political, environmental and a social movement that seeks to protect biodiversity and natural resources including animal, plant species as well as their habitat for the future. The conservation strategies may be of either in-situ type or ex-situ type.
In-situ conservation means on site conservation. It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself, or by defending the species from predators. Wildlife conservation is mostly based on in-situ conservation. This involves the protection of wildlife habitats. National Parks, Wild-life Sanctuaries, Biosphere Reserves are the examples of in-situ conservation. The benefit of in-situ conservation is that it maintains recovering populations in the surrounding where they have developed their distinctive properties. The following criteria are kept in mind during the initiative of in-situ conservation:
- Sufficiently large reserves are maintained to enable the target species to exist in large numbers.
- The population size must be sufficient to enable the necessary genetic diversity to survive within the population, so that it has a good chance of continuing to adapt and evolve over time.
- This reserve size can be calculated for target species by examining the population density in naturally occurring situations.
- The reserves must then be protected from intrusion or destruction by man, and against other catastrophes.
Ex-situ conservation means literally off-site conservation. It is the process of protecting an endangered species of plant or animal by removing it from an unsafe or threatened habitat and placing it or part of it under the care of humans. Zoos, botanical gardens and arboretums are the most conventional methods of ex-situ conservation. There protected specimens are kept for breeding and reintroduction into wild habitat when necessary and possible. These facilities provide not only housing and care for specimens of endangered species, but also have an educational value. They inform the common people of the threatened status of endangered species and of those factors which cause the threat, with the hope of creating public interest in stopping and reversing those factors which jeopardize a species’ survival in the first place. Endangered plants may be preserved in part through seed-banks or germplasm banks. The term seed-bank sometimes refers to a cryogenic laboratory facility in which the seeds of certain species can be preserved for up to a century or more without losing their fertility. A special type of arboretum can also be used where seeds are harvested and the crop is rotated. For plants that cannot be preserved in seed-banks, the only other option for preserving germplasm is in vitro storage, where cutting of plants or plant parts are kept under strict conditions in glass tubes and vessels. Endangered animal species are preserved using similar techniques. The genetic information needed in the future to produce endangered animal species can be preserved in gene-banks, which consist of cryogenic facilities to store living sperm, eggs or embryos. The Zoological Society of San Diego has established a Frozen Zoo to store such samples from more than 350 species including mammals, reptiles and birds. Instead of above mentioned positive aspects, there are few drawbacks of ex-situ conservation,
- In ex-situ conservation the target species is removed from its natural habitat, preserving it under semi-isolated conditions whereby natural evolution and adaptation processes are either temporarily halted or altered by introducing the species to an unnatural habitat.
- In case of cryogenic storage methods, the preserved specimens’ adaptation processes are frozen altogether. As a result, when re-introduced, the species may lack the genetic adaptations which would allow it to thrive in its ever-changing habitat.
- Furthermore, ex-situ conservation techniques are often costly, with cryogenic storage being economically infeasible in most cases since species stored in this manner cannot provide profit but instead slowly drain financial resources of the government or organization determined to operate them.
- Seed-banks are ineffective for certain plant genera with recalcitrant seeds that do not remain fertile for long period of time. Diseases and pests may also attack crops of protected plants and animals living in ex-situ breeding grounds. These factors, combined with the specific environmental needs of many species, some of which are nearly impossible to recreate by human being, make ex-situ conservation inaccessible for a great number of the world’s endangered flora and fauna.
However, when the extinction of a species is eminent, ex-situ conservation becomes the only option left to humanity. It is simply better to conserve a species in part than to let it die out completely in their natural habitat.