There are only 6 tiger subspecies left in the world: Here's why they are going extinct

Six different sub-species of tigers exist today, scientists confirmed amid hopes the findings will boost efforts to save the fewer than 4,000 free-range big cats that remain in the world.

The six include the Bengal tiger, Amur tiger, South China tiger, Sumatran tiger, Indochinese tiger and Malayan tiger, said the report in the journal Current Biology.

Three other tiger subspecies have already gone extinct: the Caspian, Javan and Bali tigers.

Key threats to tigers' survival across the globe

• Habitat loss
• Poaching
• Effects of climate loss
• Genomic evidence shows Breeding has also reduced drastically among different tiger populations.

How to best conserve the species and encourage both captive and wild breeding has been a matter of debate among scientists, in part because of divisions over how many tiger sub-species exist. Some say there are two types, and others believe there are five or six.

"The lack of consensus over the number of tiger subspecies has partially hindered the global effort to recover the species from the brink of extinction," said study author Shu-Jin Luo of Peking University in Beijing.

The groundbreaking research of tiger extinction

Researchers who've analyzed the complete genomes of 32 representative tiger specimens confirm that tigers fall into six genetically distinct groups.

The research helped scientists in coming to a conclusion that each subspecies has a unique evolutionary history.

The origin of the South China tiger remains unresolved since only one specimen from captivity was used in this study, the researchers note.

Tigers are not all alike

Also, tigers are distinct unlike big cats jaguars, which are found commonly across the world.

"Tigers are not all alike," Luo said, noting that key differences include body size and fur colour.

"Tigers from Russia are evolutionarily distinct from those from India. Even tigers from Malaysia and Indonesia are different."

"Tigers from Russia are evolutionarily distinct from those from India. Even tigers from Malaysia and Indonesia are different."

OneIndia News (with AFP inputs)