Fewer than 4,000 tigers remain in the wild. New research aims to give conservationists an improved understanding of their genetics in order to help save them.

After years of debate, scientists report in the journal Current Biology that tigers comprise six unique subspecies. One of those subspecies, the South China tiger, survives only in captivity.

“The results presented in this paper are important because they contradict the currently accepted international conservation classifications for tigers,” said Uma Ramakrishnan, a molecular ecologist at the National Center for Biological Sciences in Bangalore, India, who was not involved in the study.

A system recently proposed by some scientists that would classify the world’s tigers into two subspecies would harm the world’s remaining tigers rather than benefit them, said Shu-Jin Luo, a geneticist at Peking University who led the study. Preserving what is left of tigers’ genetic diversity will require ensuring that all remaining subspecies are taken into account, she and her co-authors argue.