Suhas Kumar

It is quite intriguing that Wildlife Institute of India (WII) has suddenly changed its stand on breeding and reintroduction of white tiger into wild habitats. In 2013 the WII had responded to a question whether white tigers should be bred with a view to rehabilitate them in Sanjay tiger reserve (part f the general habitat where white tigers were present till mid twentieth century. After examining this query the WII had responded that White tigers are a variant of Royal Bengal tiger and not a separate species and therefore no unique conservation value. The CWLW then apprised the government of Madhya Pradesh and the project was abandoned. Now, this abrupt turn back on its own professional opinion by WII, when apparently no one had sought a fresh opinion from them, raises doubt about the institutional and scientific propriety of this prestigious Centre of Excellence of the country.

While shifting its stand, the WII now talks of new evidence that has compelled them to change their opinion. They compare the white tigers to the melanistic tigers of Orissa that survives without any problem but they may be totally wrong in their assumption as till now no genetic study is available that unravels the mystery of Melanistic tigers of Orissa. Not very far back in time down to Earth magazine in one of its articles quoted the former Member Secretary of NTCA , Swain talking about the possible causes of melaninism in some tigers in Odisha- “Experts are attributing this rare phenomenon to many factors—climatic conditions, genetic mutation and inbreeding. “A combination of high rainfall, rising temperatures and soaring humidity may have resulted in the melanistic mutation of Similipal tigers,” says Debabrata Swain, member secretary National Tiger Conservation Authority. “In fact, the striped pattern of the habitat is being replicated on the skin of the tigers,” says Swain, indicating that the change in appearance could be the result of the existing environment. The usual preying behaviour of the tiger is facilitated by the presence of open grasslands, helping the predator to first target its prey, then chase, and finally capture it.”

Other point of views quoted in the same article is of two scientists – “The phenomenon is probably the result of a mutation or genetic change,” says Uma Ramakrishnan, associate professor, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru. “Mutations mostly occur by chance. While some can be good, resulting in better fitness and more offspring, others can be detrimental,” she says.

“Something must have happened in their gene combination, which is reflecting in the body coat,” says Acharya. He has initiated a study to find the cause.”.(Source Down to earth-By Moushumi Basu : Friday 14 April 2017)

Obviously Dr. Acharya’s research is not yet concluded. If that is the case what has compelled WII to assert that the Melanistic tigers originated in the same way as the White tigers.

Now this change in WII opinion endorsing an isolated research carried out by some Chinese and Korean scientists on white gene in Royal Bengal tiger clearly betrays compromise on professional propriety and which, I believe might have been orchestrated by some vested interests who wish to earn tourism money from white tigers. I have no issue with such businessmen as long as they keep such manufactured white tigers in safaris and zoos, but I will continue my opposition to any attempt to install such white tigers into the wild habitats. The fact is there are several others research papers that strongly oppose the idea of breeding white tigers. Are they ignoring an earlier assertion by some scientists that Cross-eyed condition in white tigers (Strabismus) is directly linked to the white gene and is not a standard consequence of inbreeding, as the orange cubs of white tigers are not prone to crossed eyed condition?

In its current letter to National tiger Conservation Authority (NTCA), the first suggestion by WII is about screening captive white tiger for genetic purity and inbreed such tigers to get white offspring. The white offspring would be trained for a life in the wild and released to fend for themselves. Perhaps the WII scientist have forgotten that in the zoos in the entire world where ever the white tigers are present they are highly inbred and a store house of double recessive genes responsible for a myriad of diseases and deformities. The proponents would not find a suitable white tiger for their programme.

Scientists who have studied the genetics of zoo bred white tigers opine as follows- “White tigers from only a few individuals, which are highly inbred in order to preserve this recessive trait. Inbreeding depression has thus become the primary cause of many health problems for white tigers in captivity, such as premature death, stillbirth, and deformities.”

‘The genetic load of a population refers to the amount of deleterious recessive alleles in that population. Most mammals have recessive alleles present in their genome (Wright, 1977; Charlesworth and Charlesworth, 1987; Ralls etal. 1988). These alleles have little to no effect on an individual when present in a heterozygous state. Inbreeding is thought to have a negative effect on the fitness of individuals by increasing the number of loci at which an individual is homozygous for these deleterious recessive alleles. As inbreeding increases, so does the probability that the two alleles an individual has at a locus will be identical by descent (i.e. derived from an ancestor common to both sides of the pedigree), and therefore homozygous (Lacy, 1997).

The second suggestion is further far-fetched and totally undesirable. It is about a breeding programme in which it is envisaged that a normal wild tigress in oestrous would be captured and kept in captivity till she mates with a captive white tiger. One the mating takes place the female will be released and monitored. The WII scientists hope that as this mating would introduce recessives genes for white colour in the cubs hence the future generations may have a few white tigers in the wild. I am surprised that how an institution like WII can suggest such an outlandish idea, while many urgent issues that plague wildlife conservation in India remain unaddressed owing to lack of effort, funds and focus.

Interestingly, in the end the letter addressed to the Member secretary NTCA, WII offers to develop a proposal for the same if the CWLW Madhya Pradesh agrees it and suggests that NTCA should inform the CWLW of Madhya Pradesh. This letter carries no reference. It is clear therefore that neither the CWLW nor the NTCA had sought any opinion from WII on this matter. For them this matter was already closed. Therefore, a question that begs for an answer is – who then pressurized WII to write this letter to NTCA.

There are research papers suggesting that the White tiger is an outcome of a base mutation in a single gene and therefore are not freaks but a variant of the royal Bengal tiger and therefore the white tiger deserves a chance to return to the jungles.

I would have agreed to this idea had there been even a single white tiger anywhere in the world whose genes have not been excessively polluted from inbreeding. The Tiger Species Survival Plan issued by the Association of Zoos and Aquariums of the USA has condemned the breeding of white
tigers.

The problem is with the stock of white tigers available in captivity across the world in the zoos. Over more than sixty years the progeny of Mohan were subjected to incessant inbreeding resulting in accumulation of undesirable traits. Such specimen should never be introduced in the wild . The Original wild tigers of Rewa might have been a robust variant of the RB Tiger that were able to survive in the wild till adulthood when they were either captured or shot but what we have today in zoos are storehouses of defective genes.One also need to understand what nature doesn’t want can never be natural. Nature has a method to deal with recessive genes – it either hides its manifestation by adding a dominant gene for same traits or replaces it with a pair of dominant genes. Nature invariably tends to eliminate a pair of recessive allele.

The white coat colour manifested in the white individuals is due to the presence of a pair of double recessive genes and such individuals are rarest of rare in nature – represented by just about 0.001% of the tiger population. In India the problem of heavy inbreeding by zoos came to light when in 2008–2009, a survey of zoos revealed a stock of 264 Bengal tigers and 100 white Bengal tigers. These numbers clearly indicate that the white tigers are being selectively inbred within homozygous recessive individuals.

Scientists who have studied the genetics of zoo bred white tigers opine as follows- “White tigers from only a few individuals, which are highly inbred in order to preserve this recessive trait. Inbreeding depression has thus become the primary cause of many health problems for white tigers in captivity, such as premature death, stillbirth, and deformities.”

The genetic load of a population refers to the amount of deleterious recessive alleles in that population. Most mammals have recessive deleterious alleles present in their genome (Wright, 1977; Charlesworth and Charlesworth, 1987; Ralls etal. 1988). These alleles have little to no effect on an individual when present in a heterozygous state. Inbreeding is thought to have a negative effect on the fitness of individuals by increasing the number of loci at which an individual is homozygous for these deleterious alleles. As inbreeding increases, so does the probability that the two alleles an individual has at a locus will be identical by descent (i.e. derived from an ancestor common to both sides of the pedigree), and therefore homozygous (Lacy, 1997).

It is quite, obvious, therefore that the entire world doesn’t have a single white tiger that could be introduced in its original habitat. And if any one says that they can produce a white tiger without crossing closely related tigers he or she is misleading you. As an Individual I have right to form my opinion and stay with it whether people agree or disagree with my arguments.

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Check: Why white tigers should not be released in wild habitats