(IN): Decoding the Sariska tiger puzzle

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*Rajasthan sent siblings to repopulate Sariska*

 

*DOOMED? Two sisters and their half-brother were selected without DNA test *

 

Jay Mazoomdaar

 

Ranthambhore/Sariska, June 28

 

As the Rajasthan forest department celebrates the anniversary of India’s

first wild tiger repopulation drive, evidence with Hindustan Times suggests

that all three big cats – a male and two females -- airlifted from

Ranthambhore to repopulate Sariska are siblings.

 

All three tigers come from the same father, known as Anantpura male. The two

females are from the same mother, known as Jhalra female or machhli. Before

selecting tigers for relocation, no DNA analysis was conducted to ensure

genetic dissimilarity. As a result, if corrective actions are not initiated,

the future tiger population at Sariska might suffer acute inbreeding

depression (See box).

 

An analysis of the photographic census data gathered by Wildlife institute

of India (WII) in 2006 clearly shows that one adult male occupied the entire

territory where these three tigers were born during 2004-2006. Tigers are

highly territorial and a male do not allow other males to breed with the

females residing within his territory.

 

“While there are enough telling evidences to conclude that all tigers sent

to Sariska came from the same father, there is nothing to suggest otherwise.

The state authorities should have used the WII expertise of DNA analysis to

eliminate the risk,” said Dr Dharmendra Khandal, a field biologist based in

Ranthambhore.

 

It is very important to conduct DNA test before introducing tigers,

particularly when we are repopulating from zero. In interconnected forests,

a bigger breeding population keeps the gene pool healthy. But one has to be

very careful about pocket reserves like Ranthambhore or Sariska,” said PK

Sen, former director, Project Tiger.

 

While Rajasthan forest bosses denied that the male and female tigers came

from the same father, PR Sinha, director of Dehradun-based Wildlife

Institute of India, agreed that only a DNA analysis could confirm it. “We

did not conduct any DNA test so far as it was not felt necessary. Having two

sisters in Sariska is not an issue but the male must be from a different

lineage for healthy reproduction. We have blood samples. We can check,” he

said.

 

Dr Ullas Karanth, India’s leading tiger scientist, felt that gene analysis

was a must for selecting tigers for relocation: “Why take chances when a DNA

test can resolve such issues? These relocation drives seem like knee-jerk

exercises done in a hurry but we cannot compromise on science.”

 

Experts, however, claim that the situation can still be salvaged. “Even if

these tigers are siblings, they are only a part of the source population as

we are supposed to bring in more tigers. If these new tigers are selected

genetically, the future Sariska population won’t be affected,” explained Dr

Qamar Qureshi, a scientist with Wildlife Institute of India.

 

Only if the Rajasthan forest department learns its lessons and opts for DNA

tests before picking up another arbitrary male for Saiska to meet its

self-imposed July 11 deadline. Ensuring genetic variation is one of the

fundamental requirements in the protocol recently issued by the National

Tiger Conservation Authority (NTCA) for tiger relocations.

 

Siblings are genetically similar and when they breed among themselves, they

are likely to pass the same lethal (deleterious) gene on to their offspring.

If the offspring receives two copies of the lethal recessive gene, it dies.

 

Other effects of inbreeding over successive generations include reduced

fertility and sperm viability, lower birth rate, higher infant mortality,

slower growth, smaller adult size, fluctuating facial asymmetry, and weak

immune system.

 

 

Jay Mazoomdaar

 

Ranthambore/Sariska, June 28

 

All the three tigers sent to Sariska so far have grown up in and around the

tourism zone of the Ranthambhore National Park. Many field guards, guides

and regular tourists have spotted and photographed them. They all have a

clear idea of their lineage and can confirm they are step-siblings.

 

“Not many will go on record fearing action against them by the park

authorities,” said Aditya Singh, Ranthambore’s well-known wildlife

photographer. “But we have seen these tigers grow up. The male was born to

the tigress in the Chiroli zone of the park, and the two females to another

tigress in the Jhalra zone. All three cubs were fathered by the same male as

he was the only dominant tiger in that area since 2004. He has been filmed

mating with the Jhalra tigress. I can’t believe the park authorities did

not know this.”

 

Hindustan Times has analysed the Wildlife Institute of India’s 2006 tiger

census. The census extensively used camera traps and clicked 356 photographs

of 31 tigers in Ranthambhore over 19 days.

 

The result threw up five adult males – two of them too young to have

fathered the male cub born to the Chiroli tigress. It clearly defined the

territories of the three other males, as well as that of the Jhalra and

Chiroli females.

 

As the accompany map of Ranthambore shows, the territories of the Jhalra and

Chiroli females fall within the territory of Anantpura male. Except under

rare circumstances, the other males in the park could not have mated with

either of the two females without dislodging the Anantpura male from this

area. It follows that all cubs born to the Jhalra and Chiroli females during

that time were fathered by Anantpura male.

 

“Very rarely will a male tiger allow other males in his territory,” said

Fateh Singh Rathore, ex-conservator of Ranthambore. “I do not see any chance

of any other male mating the Anantpura male’s tigresses.”

 

“The fact that the Anantpura male shared space with the Chiroli male cub

indicates that they are father and son. A male tiger would kill the litter

of another male,” said P.K. Sen, former director, Project Tiger.

 

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