ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

[peter]

ANSWERS TO THE FIRST TWO QUESTIONS IN POST 1,222


1 - Introduction

Yesterday, Parvez asked me if I had read a recent article about the genetics of tigers in the Terai Arc Landscape. I hadn't, but adviced him to contact Tigerluver. He did. Today, Tigerluver posted the link to the article in the thread 'The Terai Tiger':  

http://wildfact.com/forum/attachment.php?aid=915

The title of the article, accepted on October 18, 2010, is 'Genetically distinct population of Bengal tiger (Panthera tigris tigris) in Terai Arc Landscape (TAL) of India'. The article, an 'original investigation', was written by R. Sharma, H. Stuckas, R. Bhaskar, I. Khan, S.P. Goyal, S.P. and R. Tiedemann and published in 'Mammalian Biology', 76 (2011): pp. 484-490. The project was supported by the DAAD (German Academic Exchange Service) and the University of Potsdam. Markward Fischer of the 'Senckenberg Naturhistorische Sammlungen' (Dresden) assisted in the figures department.


2 - Abstract

The authors analyzed mtDNA polymorphisms in 91 scats and 12 tissue samples of tigers from 3 different populations in northern India; the Terai Arc Landscape (TAL), the Buxa Tiger Reserve (BTR) and northeastern India. Now for the results:

2a - They found a specific haplotype in TAL and BTR. As this haplotype was absent elsewhere, the conclusion is that tigers in these regions (TAL and BTR) are genetically different from those in other regions in India.

2b - Within the TAL region, they found some evidence for genetic isolation of tigers west of the Ganges river, like the western part of the Rajaji National Park (RNP). The isolation, most probably, wasn't a result of the river, but of human-induced changes and degradation of the Motichur-Chilla Corridor.

2c - Apart from the western part of the Rajaji National Park, the tiger population in the TAL, a region with a length of 900 km. and a width of 50-60 km., was genetically cohesive.

2d - Tigers of Royal Chitwan National Park in Nepal, in spite of its proximity to the TAL-region, are genetically different from tigers in the TAL-region.

2e - Tigers in the northeastern part of India are different from TAL and BTR tigers. They're also different from Chitwan tigers and tigers in others regions of India.    


3 - Haplotypes in 7 Indian regions

The article has a map with haplotype frequencies in 7 Indian regions (northeastern India, Buxa (BTR), Chitwan, northern India (TAL), western India, central India and southern India. Of these 7 regions, 4 have haplotypes not seen in other regions. They are northern India (4 unique haplotypes - TIG 8, TIG 11, TIG 12 and TIG 13), northeastern India (2 unique haplotypes - TIG 14 and TIG 15), Chitwan (1 unique haplotype - TIG 4) and southern India (1 unique haplotype - TIG3).

Haplotype TIG5 is most often shared (northeastern India, Chitwan, western India, central India and Southern India). Haplotypewise, northeastern India has connections with Chitwan (low), western India (high), central India (moderately) and southern India (high). There is no connection between northeastern India and Bux (BTR) and northern India (TAL).


4 - The answers to the first two questions in post 1,222

4a - Are tigers in mainland India different from those just south of the Himalayas? The answer is yes regarding tigers in the TAL-region and Buxa (BTR) and no regarding Chitwan. Tigers in the TAL-region and Buxa (BTR) do not share a single haplotype with with tigers in western, central, and southern India. Chitwan tigers, on the other hand, share haplotype TIG6 with central India and TIG5 with western, central and southern India. Chitwan tigers also have a unique haplotype (TIG4). Same for tigers in southern India (haplotype TIG3).

4b - Are there differences between regions in mainland India? The answer is no. Tigers in western, central and southern India share haplotype TIG5 (75% and over in all regions). Central Indian tigers share haplotype TIG6 with Chitwan tigers and western India tigers share haplotype TIG10 with tigers in northeastern India. Tigers in southern India are a bit different in that they have a unique haplotype (TIG3). 


5 - Conclusions

5a - Tigers living just south of the Himalayas are genetically different from tigers in others regions in India. It is, however, remarkable that tigers in northern India (TAL) and Buxa (BTR) share haplotype TIG7 (well over 85% and only seen in these 2 regions), whereas Chitwan, located between the TAl-region and Buxa, show no trace of this haplotype. Not at all.

5b - Tigers in northeastern India are genetically also are very different from tigers in other regions, but they share some haplotypes (TIG2, TIG5 and TIG10) with tigers in western, central and southern India. This is not true for tigers in the TAL-region and Buxa.

5c - Chitwan tigers are an enigma. As it isn't a result of geographic isolation (Chitwan is connected to the TAL-region), the question is why Chitwan tigers are not related to tigers in Buxa and the Terai Arc Landscape. Reply