How many types of tigers are there?

Molecular Genetic Technologies Resolve Explicit Precision and Distinctions Among All Living and Extinct Subspecies of Tigers

Living tigers are severely endangered in their fragmented range across Asia numbering as low as 3000 wild individuals that remain  in a handful of tiger range countries.  Tigers have been  traditionally subdivided into eight principal subspecies based upon geographic provenance and subtle morphometric traits for over a century.  Four of these subspecies (Javan, Bali, Caspian and South China tigers) disappeared from their former natural range in the 20th century, leaving relict populations of the Bengal (Indian), Indochinese, Sumatran and Amur (Russian Far East and northeast China) surviving today in small  vulnerable populations, objects of intense conservation concern and protection.

Tiger subspecies recognition and classification is important because the subspecies boundaries often coincide with geo-­‐political boundaries between countries that do not always agree on a unified conservation approach.   Further, subspecies recognition has been somewhat controversial since selected morphological traits and geographic boundaries of tiger range are dynamic, capricious and imprecise.  Today, an international team of scientists from China, USA, UK, Israel, Russia, and Qatar released a comprehensive molecular genetic reassessment of tiger subspecies population structure, their relative relationship and a plausible interpretation of tiger natural history that led to the present disposition of surviving  subspecies.

Published online  today in the  May 1, 2015 edition of the Journal of Heredity, the report describes DNA signatures for 145 individual tiger specimens including so-­‐called “voucher specimens” of tigers from verified geographic origins including Eurasian museum specimens for the extinct Caspian,  Javan and Bali tiger subspecies.

The culmination of a ten-year study using both mitochondrial DNA sequence and nuclear microsatellite markers led by Shu-Jin Luo of Peking University and Stephen OBrien of Theodosius Dobzhansky Center for Genome Bioinformatics in St Petersburg, Russia, revealed clear molecular genetic distinctiveness among Amur, Bengal, Indochinese and Sumatran tigers. The team’s first results appeared in 2004 announcing the Malayan tiger splitting from its Indochinese counterpart as a distinct, new fifth living tiger  subspecies. However today’s report offers evidence that the extinct Javan and Bali tigers were near indistinguishable in molecular genetic distance from Sumatran tigers, as the extinct Caspian tigers are similarly near identical to the surviving Amur tiger subspecies, raising the prospect of revising subspecies nomenclature.

The new results, though probably not the last fine-­‐tuning of our understanding of tiger subspecies status, are important in designing management strategies for protecting each surviving subspecies of tiger and stabilizing the march toward extinction that tigers are clearly suffering.  The identified diagnostic markers also provide powerful methodology for forensic   identification of subspecies intercrosses in captive populations or subspecies identification of trafficked bones and skins in illegal trade enforcement. As human DNA forensics revolutionized capital crime prosecution, the tiger DNA profiles offer  powerful tools in  wildlife protection as well as in reducing illegal wildlife commerce.

Contacts:

Shu-­‐Jin Luo, Ph.D. Principal  Investigator College of Life Sciences Peking  University Beijing 100871, China Tel: +86-­‐13811457516

Email:  luo.shujin@pku.edu.cn

Stephen J. O'Brien, Ph.D. Chief Scientific Officer

Theodosius Dobzhansky Center for Genome Bioinformatics St. Petersburg State University

41 Sredniy Prospekt

St. Petersburg, Russia 199004 Russia (011)+7 981 801 7983

SKYPE ID:  lgdchief     EMAIL:   lgdchief@gmail.com