International

Genetics confirms that there are 6 subspecies of tigers (not 2 or 5)

A team of geneticists confirmed that there were six subspecies of surviving tigers today, not two or five as other classifications suggest.

The number of subspecies is important for the conservation strategy for tigers, an endangered species whose wild population is estimated at less than 4000 animals, in a territory reduced to 7% of its historical zone, on the Asian continent (the tiger does not live in Africa in the wild).

Two Chinese researchers led the study that analyzed the genomes of 32 tigers. Their results were published Thursday in the journal “Current Biology”.

The traditional taxonomy recognized eight subspecies, three of which were extinct, but in 2004 a team of researchers, led by geneticist Shu-Jin Luo of Peking University, proposed a ninth, the Malaysian tiger (Panthera tigris jacksoni), as distinct from the Indochina tiger. The work published Thursday, led by Ms. Luo, confirms its existence at the genome level.

The six surviving subspecies, all in Asia, are from north to south: the tigers of Siberia, South China (not found in the wild), Bengal (sometimes white), Indochina, Malaysia and Sumatra.

In 2015, researchers proposed redefining only two subspecies: the continental Asian tiger and the Sunda tiger (Sumatra, Java, Borneo).

Animals of different subspecies can breed with each other, unlike animals of different species. They are traditionally separated according to arbitrary criteria based on geography, morphology … and genetics.

The new genome analysis also allowed us to go back in time to better understand the history of evolution of tigers.

“Modern tigers date back to around 100,000 years ago,” Shu-Jin Luo, who has been working on these felines for 15 years, told AFP. This common ancestor is therefore relatively recent, which is surprising, because we have fossils of tigers dating back more than two million years.

The huge volcanic eruption of Toba, considered by some researchers as one of the worst volcanic disasters in recent Earth history, about 75,000 years ago, may have killed most tigers, says the researcher .

Only a few individuals would have survived the long climatic chill triggered by the eruption … including the ancestor of modern tigers.

The correct genetic distinction of tigers should be used to guide conservation patterns. “They are the result of adaptation to their respective habitats and ecosystems,” says Shu-Jin Luo. “It is this uniqueness of evolution that wildlife protection actors are trying to preserve.”