Species extinction, an `evolving process'

THIRUVANANTHAPURAM May 29. While the threat of extinction faced by rare species from development programmes continues to raise a storm of protest, environmental studies of the biosphere have drawn attention to how extinction of species results also from evolving ecological process,

According to the Centre for Earth Studies here, naturally protected `sacred' groves exist in the State under a variety of ecological conditions, the largest being them Iringole kavu, spreading over 20 hectares.

Hoofed species, known as `ungulates', in Kerala and Tamil Nadu, do not seem to have been rated very high under the environmental protection measures launched by the Government though they have been listed as `vulnerable', `threatened' or `endangered'.

Only eight out of the classified 34 ungulates have been assigned a satisfactory protective status and these include the Malabar Civet and the Southern Swamp Deer.

The other surprising finding is the presence of `wild relatives' of paddy in the densely populated coastal plains of Kerala which might have been expected to be present only in `extensive tracts of pristine ecosystems'.

The biosphere reserves in Kerala, Karnataka and Tamil Nadu which are environmentally protected spread over 5,529 sq km while the tiger reserves of Kerala in Periyar extend over 777 sq km, and they are much smaller than those of Nagarjunasagar in Andhra Pradesh, (3,568 sq km), Bandipur in Karnataka (866 sq km) and Kalakad Mundanthurai in Tamil Ndu (800 sq km). The Tropical Botanic Garden and Research Institute here is engaged in developing strategies and undertaking in situ conservation of rare plant species.

The study of habitat preferences of large and medium-sized mammals in the Parambikulam Wildlife Sanctuary revealed that herbivores and carnivores were most abundant in grasslands and plantations.

Pointing out that `species extinction is a natural process', the studies focus attention on the evidence from fossil records, which indicate that species become extinct because of `transformation over evolutionary time or they divide into two or more separate lineages'.

This is known as `pseudo-extinction', as it results from evolutionary changes like glaciation, instead of only through deforestation by humans. Chance or random events known as `stochastic processes' act independently or `influence variation in deterministic processes'.

The four types of such processes are (i) demographic uncertainty resulting from random events in survival and reproduction (ii) environmental uncertainty due to unpredictable changes in weather, food supply, threat from predators and parasites (iii) natural catastrophy like floods and (iv) genetic uncertainty brought about by random changes in genetic make-up.

The studies have further revealed that while the prevailing abundance of a species ensures survival over an evolutionary period, a rarity of the same quickens its extinction.

It is still not known why some species, which are vulnerable to evolutionary extinction, have remained rare in spite of non-intervention from the humans or other predators. Wherever species have migratory instincts, they are known to have survived longer.

It has been estimated that one million species had become extinct between 1975 and 2000

The Global Biodiversity Assessment Report of the United Nations Environment Development Programme has pointed out that management deficiencies weaken the ability of India's Protected Ares Network for conserving a representative of the country's biodiversity.

The Indian Institute of Public Administration has recommended a number of measures for improving the situation and some of them are under implementation.

However, in spite of species extinction resulting grom ecological changes is now recognised as a fact, environmental destruction brought about by spread of industrialisation is still a major destructive presence.

It has been estimated that half of the species in tropical rain forests (like those of Kerala) around the world had become extinct between 1975 and 2000 and this is attributed to deforestation.

An alarming prediction is that by 2020 the extinction of forest species could be between to 6 to 15 per cent of their present number if deforestation is not arrested.

These studies, just published as `Economics of Protected Areas and its effect on biodiversity', have been carried out by Ram Bir Singh Kushwaha and Vijay Kumar of the Indian Institute of Forest Management, Bhopal.

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