White Bengal Tigers: A Harmful Genetic Mutation
Interactions between the white Bengal tiger and man resulted in death.
Historically, when they were come upon by humans, white tigers were immediately shot, stuffed, and displayed. Earliest records describe a tiger shown at Exeter Change as early as 1820.
Another taxidermist creation was famously gifted to King George V from the Maharajah in the early 1900s.
The capture of Mohan, the father of all modern white Bengal tigers, took place in 1951 and was not any less violent.
The Maharajah was notified that a tigress had been spotted with a white cub and a search for its retrieval was begun immediately. Not only was the tigress shot, but two of her cubs were killed as well. Mohan escaped only to be later caged, clubbed, and tied up.
From that moment on, Mohan was used for the purpose of producing more white tigers.
Mohan was first bred to a tigress called Begum. However, this tigress did not possess the required gene combination and together they produced only normal orange colored cubs. Mohan’s second partnership was with one of his and Begum's orange offspring. This pairing was just the beginning of a long history of inbreeding that is still practiced today.
Mating with his daughter proved highly successful and she gave birth to four white offspring. This strategy was repeated again, and again, pairing Mohan with daughters from each successive litter. Continually mating father to daughter provided one white litter for every three orange ones. Additional incestuous pairings were made as well. Two siblings from Mohan’s first all-white litter were given to the National Zoological Gardens, where they were mated to produce twenty offspring, all white.
White fur is a genetically recessive trait. Under normal circumstances, it statistically occurs only in one out of every ten thousand cubs that are born. It is an undesirable as well as unusual characteristic. Odds are that a white cub will be especially susceptible to predation and have difficulty catching food, as it cannot blend into its surroundings. Because of this, few of these already rare animals reach adulthood.
In conclusion, a white tiger first being born and then living to maturity is unlikely. Nine thousand, nine hundred and ninety-nine orange cubs will be born before this event occurs, each with a superior chance for survival. The odds of a parent mating with his or her progeny repeatedly to create white furred progeny at such an accelerated rate that multiple white cubs are produced for every four litters is virtually impossible. That is, if not for human interference.
But humans interfered continually, and the results were anything but normal.
Genetic variation is key for maintaining health in a population. Because white tigers were so repeatedly inbred, variation in the population was very low. And because of this genetic mutations, or gene-linked abnormalities, were very high.
The litters following Mohan’s first white furred progeny are great examples of this phenomenon. Of one hundred and forty eight cubs born, seventy two died from health-related complications. Cubs were born with eyes that crossed, curved spines, and distorted necks (undesirable mutations). With each passing generation, genetic defects became more and more concentrated and the instances of abortions and unsuccessful births increased, with fewer cubs surviving. On average, each of the tigers that did survive lived a reduced lifespan.
Fortunately, over time zoos' breeding practices shifted to be more beneficial to the animals.
It is now common practice to outbreed tigers, or mate two unrelated parents, one white and one orange. Then the resulting offspring are mated to each other. Although this still mates siblings, having one unrelated parent reintroduces new genetics which reduces mutations. Some zoos claim that they practice such good breeding strategies that they have no unusual mutations at all. They claim that mutations exist elsewhere at other institutions only because of inferior practices.
The reason inferior mating strategies may still be used is because intense inbreeding is highly profitable. By breeding two white tigers, instead of a white to an orange one, more white offspring are produced at a faster rate. This ultimately means more money, as a white tiger has been estimated to be worth around $60,000. If for every one healthy-looking white tiger multiple siblings are born deformed, this profit still makes it monetarily worthwhile. The only price paid is in the health of the quickly produced animals, not by the breeder.
A debate currently exists: Is it ethical to breed white tigers?
Those against the practice of breeding white tigers claim that it is inhumane because of the deformities that can take place. They also dislike that the animals are sometimes mated with other subspecies to introduce new genes to the population, rendering the lineage murky at best. Because the white tiger is the same species as the orange tiger, some find their conservation unnecessary, as they are essentially the same animal.
Those in favor of white tiger breeding have arguments of their own. First of all, they believe that the modern practice of outbreeding has reduced many unfortunate deformities usually frequent in highly inbred populations. Further, the animals attract so many people and bring in so much profit that they are indispensable. People come to the zoo to see the tigers, and thereby learn about the wider fight for endangered animal conservation. The money they provide to the zoo can be used to benefit many other species.
Do benefits outweigh possible risks?