On this surface of the earth, where evolution is in operation, extinction of unfit and rarity of less fit in natural selection is an evolutionary necessity. Therefore, extinction is not an abnormal process in the life of a species. Extinction is generally considered to be the death of the last individual of that species or the end of an organism or group of taxa. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Whenever all the niches of an ecosystem are occupied, extinction occurs as a part of the origin of new species. Thus extinction is a must for the survival of the fittest.
Through evolution, new species arise by the process of speciation where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche and species become extinct when they are no longer able to survive in changing conditions or against superior competition. Extinction, though, is usually a natural phenomena; it is estimated that 99.9% of all species that have ever lived are now extinct. It is estimated most species that go extinct have never been documented by scientists. Some scientists estimate that up to half of presently existing species may become extinct by 2100. This is an alarming situation and an unenviable condition in the natural process of environment.
The grandiose achievements of man in the scientific and technological fields have led to an upsurge of industrialization, urbanization, growth of population, proliferation of consumer goods, dams and other big projects, which are considered to be the hallmark of progress and development. On the other hand we are faced with colossal problems of depletion of natural resources, contamination of our rivers, lakes and seas, shortage of food, water, land and air, toxic waste dumping on land, rivers and sea. The world has come to realize the development is exerting such a great pressure on the nature and its biodiversity that the growth process itself has begun to slow down. Impoverishment of nature is resulting in the impoverishment of man.
The present day drastic changes in the environment and habitat due to human activities are so unnatural that the species are not getting full liberty of time and space for their survival and adaptive radiation, therefore, resulting loss of habitat, biodiversity leading to the extinction of the species. The extinction of a particular species or taxa in a habitat or an ecosystem triggered a chain reaction of extinction of the fellow or the other species in the ecosystem.
Recently, the Alaotra Grebe(Tachybaptus rufolavatus), also known as Delacour’s Little Grebe or Rusty Grebe, has join the elite group of extinct bird species known to the modern world following the steps of other 190 species of extinct birds since A.D.1500 like Dodo, Martha (Passenger Pigeon) Labrador duck, Javanese lapwing, White-winged sandpiper, Rodrigues pigeon, Heath hen and Pink Headed duck.
A closer look at the extinct bird list reveals a suite of familiar bird groups such as petrels, herons, ducks, moorhens, pigeons, doves, parrots, thrushes, warblers and starlings that have been lost. Alaotra Grebe also joins two other species of grebe which have become extinct as recently as the last quarter of the 20th Century – Colombian Grebe and Atitlan Grebe. On the 26th of May, 2010, Birdlife International has officially declared the extinction of Alaotra grebe (Tachybaptus rufolavatus) from the red list registering another event marking as one of the darkest hours in environmental history.
Alaotra grebe (Tachybaptus rufolavatus) was endemic to Lake Alaotra of Madagascar. The size of the bird was about 10 inches in length and it was not a long distance flyer because of its small wings. The species was last seen in the year 1985 and the experts doubted the species as hybrid with Little grebe.
The species declined in the course of the 20th century, mainly because of habitat destruction and predation by the introduced snakehead Murrells (Channa striata). Also, the few remaining birds increasingly hybridized with Little Grebes which use the wetlands as a migration stopover site; as the species differed in several key aspects, the hybrid birds may have suffered from decreased fitness to the detriment of the rufolavatus gene pool.
Many conservation expert and scientist warn that if deforestation, desertification and destruction of wetland and coral reefs continue at their present rate, at least 50,000 and perhaps 1 million species will become extinct as a result of human activities between 1975-2015. Using the lower estimate, this amounts to an average extinction rate by 2015 of 20,000 species a year or 1 species every thirty minute. A simple arithmetic of the present trend is that no living organism including the human being on earth will not be able to survive for more than ten century in this world. There is thus 200-fold increase in the extinction rate in only 40 years. Most of the species will be plant and insects that they are yet to be classified and not much is known about their use to the people and their role in the ecosystem.
As reported by the WWF as many as 500 million (species) kinds of plants, animals and microorganisms have made earth their home since life began over 3.5 billion years ago. Presently, it is believed that there are only 8-10 million species alive. Then, where those rest of the 490 million species has gone? This is a million dollar question where lies the very survival of the diverse forms of life including human beings on earth. Thus since life began, about 490 million species have become extinct. They are no longer exists outside museum and photographs.
Why we should conserve biodiversity and mourn on the extinction of these diverse forms of life from the surface of the earth?
Each individual species depends upon others for its existence and links between different species hold life together. If one species is removed then the others that depend upon it will also die or seriously affected. Some species are so important that without them their whole ecosystem will collapse.
Another reason for conserving biodiversity is because humans are dependent upon it; we depend on biodiversity for our food, medicines, and shelters and for many industrial purposes. As we lose species, we are also losing potential new medicines and foods that may needed to continue human life on earth. Conserving biodiversity means judicious use of the natural resources but not exploitation. All this require scientific awareness and scientific temper. Let us remember, extinction is forever and is an irreversible process.
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