Identification of Species for Ex-Situ Conservation

With a multitude of species likely to be lost in near future, we shall have to pick and chose the important ones which we can preserve as we cannot conserve all of them. Naturally we shall have to devise some criteria for the selection of species to be placed under ex-situ conservation efforts. These criteria may include:

1. Vulnerability of the species to extinction.

2. Economic, ecological or aesthetic importance of the species.

1. Vulnerability of Species to Extinction :

The expansion of human enterprise in near future will inevitably result into fragmentation of natural habitats which shall in turn cause disappearance of one species after the other. There is considerable evidence to suggest that the number of species in an isolated patch of habitat decrease over time.

Therefore, with so many species likely to be extinct in near future, a crucial issue for conservationists is to identify those species which are most at risk of extinction after habitat fragmentation from the knowledge of their biology and ecology. A number of attributes or traits of life cycle have been proposed as factors determining the species vulnerability to extinction (Karr 1991, Laurance 1991). Important among these include:

1. Rarity:

Abundance of species before fragmentation is an important criteria for determining the vulnerability of the species to extinction. It has been found that after fragmentation, rare understory birds occupy fewer forest fragments per species than common ones. Thus fewer individuals of rare species as compared to the common species are likely to occur in habitat fragments. Such species are prone to extinction sooner than other species.

2. Dispersal ability:

Species capable of migrating between fragments of habitats or between mainland areas and the fragments are able to nullify the effect of small population size. Thus mobile species which are capable of migration with ease and swiftness are not at much risk of being lost.

3. Degree of specialization:

Specialized species usually use and subsist on resources which are distributed in small patches in time and space. These resources are likely to be effected more frequently than others. The reason for rarity of specialized species is the rarity of these resources. Such species are, therefore, more prone to extinction. Specialized species may also be vulnerable to succession changes in the habitat fragments and to the break-down of co-evolved mutualism and food web.

4. Niche location:

Species adopted to or able to tolerate conditions at the interface between different types of habitats are less affected by habitat fragmentation than others. These species are actually benefitted by habitat fragmentation. Species intolerant to conditions of life at the interface between two types of habitats are more prone to extinction in a relatively shorter time.

5. Population variability:

Species with relatively stable populations are much less vulnerable to extinction than those which undergo large fluctuations in population densities. The population of those species with stable population is unlikely to fall below the critical threshold from which it is difficult to recover.

6. Trophic status of the species:

Animals at higher trophic levels are usually less abundant and thus more vulnerable to extinction because of rarity.

7. Adult survival rate:

Species with naturally low adult survival rates are usually more vulnerable to extinction than those species which have higher adult survival rates.

8. Longivity:

Usually long lived animals are less vulnerable to extinction than that specie which has shorter life span.

2. Economic, Ecological and Aesthetic Importance of the Species :

Once the likelihood of extinction of species has been assessed, the choice of species for ex-situ conservation rests on its economic, ecological and aesthetic importance. As the resources available to us are limited and cannot be applied to all the endangered species, the species which are or are it likely to be more important to man in near future among the endangered species shall be preferred ft ex-situ conservation. There is little logic in conserving and wasting our limited resources on specie which has no use for man in future.