TEST-TUBE WILDLIFE? - Perhaps The Only Option
Aswini Pai

The major threat that all species are facing today is habitat loss due to anthropogenic (man inflicted) pressures.  As the wilderness shrinks, many species (plant and animal) are faced by not just the problem of a loss of numbers but also isolation from their own populations distributed in other areas subsequently leading to a loss of genetic variation, an inability to adapt to changing environments and increased susceptibility to disasters.

Though India’s protected areas amount to only 4.6 percent of its total land, even these lie in small and isolated pockets.  Many of the species which occur in India are now in fragmented or unique (the one and only) populations, in dire need of conservation and proper management to ensure their survival.  The species are many -- the asiatic lion, the sangai, the brasingha, the one-horned rhino, the wild ass, the wild buffalo, the great Indian bustard, the hangul.  The list is ever expanding.  It is essential to recognise the need for efficient management to preserve, if not conserve, them.

Most plant and animal populations consist of several geographically separated deems (sub populations) between which migrations occur.  Species can be of low densities in areas (e.g. raptors, carnivores) or consist of clumps of individuals in local populations having a high density (e.g. most ungulates).  The distribution of any species is subject to the presence or absence of ecological barriers (discontinuity of habitats) and its need for a particular kind of habitat.  Man’s activities and his landuse decisions have had drastic impacts on the continuity of habitats.  This phenomenon better known as habitat fragmentation has caused the isolation of various deems of plants and animals form each other.  Several animals have migratory patterns that help maintain a gene flow among deems but as habitat fragmentation and geographical isolation take place these migrations cease.  Urbanisation in India coupled with agricultural advances have reduced forests to a few patches, effectively blocking traditional migratory routes of many animals and the distribution of vegetation types.

Isolation factors need to be better understood.  As populations of a species get isolated from each other we get “localised gene pools”, the implications of which are a decrease in population size and viability; loss of genetic variation; inbreeding and speciation (the divergent evolution of members of the same population into different species).  All these effects can be pinpointed to a cessation of gene flow and the survival of a population is often dependent on a combination of the above.

Decrease in Population Size and Viability
In a closed population where immigration is absent) the number of individuals dictates genetic variability and reflects on long term survival of the population. Small populations face intrinsic threats like genetic and demographic variation and extrinsic threats like environmental variation.  Small populations can be exterminated by epidemics and catastrophes as has happened with distemper killing the black footed ferret and the attack of an epizootic on the Ngorongoro lions.   Small populations are also vulnerable to competition from exotics.

A term that is being used frequently these days is minimum viable population (MVP) - magic number for a population below which it is doomed to extinction.  This number is abstract and is subject to environmental conditions, species characterstics and even human demands.  Rare species may persist despite prediction of extinction because they are not governed by dynamics with strong environmental variance.  To account for all the factors affecting the survival of a population we now have a technique called PVA (Population Viability Analysis).  PVA is used in wildlife management to estimate extinction vulnerabilities of small populations using computer modelling for an array of factors and for the selection, implementation and evaluation of management programmes in wildlife areas.

Usually viable populations are too large to be maintained in the reserves.  PVA has been used in studies of grizzly bear, northern spotted owl, eastern bandicoot rat and several other endangered species.

Loss of Genetic Variation
When a population is small and isolated, it’s genetic variability decreases.  Genetic variability (a diversity of genotypes) often ensures that a species can adjust to environmental change.  Species like the cheetah; elephant seal and the bison which have passed through a stage of low population number or ‘bottle necking’ in the past show low genetic variation.   This effect has been studied among the Isle Royale wolves in Canada which had all originated from a single breeding pair that had been introduced to the island.  Though deleterious genes may be purged in the process of bottlenecking, in the long run invariable populations may not be able to respond to environmental change.  Inbreeding can further decrease genetic variation.  Computer simulations like Gene Flow estimate genetic variation for generations of living specimens.

New genetic variations can be generated by mutation.  But the probability of mutation, its selection and fixing in a population takes a considerable amount of time.

Speciation is a phenomenon which can be thought of only in the evolutionary time scale.  As each deme is separated, divergent processes take place.  A good example is that of the asiatic, allopatric wild asses.  All the species are adapted to an arid environment.  Chromosomal divergence occurred in the various populations more than 500,000 years ago as a result of geographic isolation.

Another example of speciation that may be taking place is the Barasingha which has been differentiated into two sub-species due to geographic isolation - the soft ground Barasingha in north India and the hard ground Barasingha in central India.

Inbreeding When closely related individuals sharing common ancestors mate, the phenomenon is known as inbreeding.  The most notorious effect of inbreeding is increase in the numbers of homozygous  lethal genes resulting in “defective animals”.  Very rarely does inbreeding occur in the natural system, especially in animals.  Inbreeding is more common in plants - tomato, oats, wheat, peas, beans, barley are all examples of self fertilising plants.  Studies on zoo animals have shown that inbreeding can result in juvenile mortality, loss of fertility, spermatozoal abnormalities, cannibalism in carnivores and an increased susceptibility to infections.

Management Strategies
The management can contemplate two options for an endangered species - either in situ or ex situ conservation.
In situ conservation involves preserving a population in its natural habitat and is the best conservation measure.  In situ conservation needs a protected area, a knowledge of the number of individuals in the population to be protected for long term survival and some measure of the habitat quality.  It is best to have reserves situated in places with a very high level of endemism.  Several small sites rather than one large area must be considered so that unique populations can be split up into smaller units to avoid catastrophes.  The need for migratory corridors between populations is essential, especially in the case of territorial and far dispersed animals with low densities (e.g. tiger, musk deer) both to avoid inbreeding and to have viable populations.  With migration loss of local populations can be counterbalanced with immigrants.  We must ensure that dynamics of succession do not destroy existing essential habitat.  For example, in Dudwa and can reduce Kanha National Parks woodland encroachment is controlled by sporadic fires.  Prevention of disturbance is necessary.

Ex situ conservation can be done either by captive breeding or biotechnological means.  Captive breeding preserves the whole animal while biotechnology focuses on preserving the germ plasm present in a few of the body parts, using it to propagate progeny.
Captive breeding preserves species in plantations, botanical gardens, zoos, aquaria or ranches.  Captive populations are often subjected to intensive inbreeding because the founder population consist of a few individuals (scarcely enough to represent genetic variation) and wrong management.  Unnecessary, short generation intervals are kept and only a small fraction of the population reproduces since zoos prefer to exhibit a family and its offsprings.  Preventing inbreeding an maintaining genetic variation can be done with the exchange of animals or genetic material (semen) between various lineages in zoos, by careful back- crossing with the founders and introducing more members from the wild.  Mixing of strains is also common in zoos.  An example is captive populations of the asiatic lion being mixed with the African lion in zoos.  Adaptation to captivity can reduce an animal’s chance to survival in the wild.  Zoos often lack space and are unable to provide proper food.  Over crowding and unhygienic conditions lead to a susceptibility to diseases.

Captive breeding programmes were initiated in the early 1960’s.  Captive breeding supplements in situ conservation.  Examples are the reintroduction of the Californian condor - the last three individuals in the wild were captured, captively bred to 40 individuals and released into the wild; whooping cranes were bred successfully in captivity and reintroduced; zoo stock was used for the successful reintroduction of the arabian oryx in Oman; in the USA depleted and outbred red wolf populations were replenished by a captive breeding programme which bred pure line red wolves and later introduced them to a protected habitat.  More populations being considered for reintroduction from the zoo population are european bison, blackfooter ferrets, hawaian goose, kemps ridley turtle, sangai and the asiatic lion.

Biotechnological conservation is a relatively new field.  Though gene banks for the preservation of economically important species were common, wild species are being preserved by these methods only recently.  Technologies like cryopreservation of germ plasm can conserve the genetic resource.   Genetic vigour in both captive and wild fragmented populations can be enhanced by reproductive biotechnology.  The techniques used are in vitro fertilisation (IVF), embryo transfer (ET) and artificial insemination (AI).  Artificial propagation has been tried out in elds deer, blackfooted ferret, tiger, Indian desert cat, leopard cat and cheetah.  Though the outlook of preservation of the germ plasm seems preposterous, it may be the only opinion left if we wish to conserve the genome (genetic code unique to a species) for posterity.

Indian efforts are far less impressive compared to other countries in the field of the conservation of wildlife.  With the high level of endemic plant species in the Indian subcontinent  more effort must be made to develop botanical sanctuaires.  More corridors must be provided to link protected areas.  These corridors may or may not be semi protected, allowing some amount of regulated human activity, these will form pathways of migration and dispersal thus removing limitations on the gene pool.  Unique populations like Gir’s asiatic lion may be abundant in their number and man-animals conflicts have increased.   Translocation of a few lions to another suitable habitat would help reduce local pressure and build up another contingency population.  The sangai deer in Manipur has a restricted habitat and a very much reduced population size.  Introduction of sangai form captively bred population into the wild after some genetic manipulation would also create an alternate population.      

Whatever the method of conservation, in situ or ex situ, what is important is the survival of the species.  Ex sit conservation must complement in situ conservation.  Merely declaring a protected area is not enough. When a population ebbs what would be most important would be the building of the numbers rather than bothering about the genetic consequences.  Solutions to genetic drift, inbreeding and founder effect follow only if the population has a health number (viable) of individuals.  Theoretical models must incorporate practical parameters and thus be applicable to real life populations without much room for errors.

The application of biotechnology must be weighed further and used judiciously since a small population does not leave much to be experimented with.  Before considering the bleak prospects of test tube wildlife let us do the best we can to protect the population within their habitats.

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