Snow leopards are those high altitude cats that have long fascinated Westerners. Peter Matthiessen won a national book award for writing a memoir about his trip to the Himalayas to go looking for one, and for most of my life, we had no idea how many were around or where their exact range was. Huge debates about their taxonomy weren’t even resolved until recently, when it was finally settled that they were indeed members of the genus Panthera and that they were a sister species to the tiger.
But as we’ve looked at the snow leopard genome, something really odd has come to the fore. In the bulk of their genome, they are clearly closely related to the tiger, but their x-chromosome and mitochondrial DNA are oddly quite close to those of lions.
In 2016, genome comparisons were performed for many cat species, and the researchers found that these lion-like x-chromosomes and mitochondrial DNA entered into the snow leopard population just before the lion and leopard split. The authors think that there was an introgression between the ancestral male snow leopard and female lion/leopard ancestor. This matriline is now all that survives in snow leopards.
So yes, snow leopards are most closely related to tigers, but they did receive some genetic contribution from the lion and leopard ancestor. This hybridization happened over two million years ago, but it is the closest thing to a liger ever occurring in the wild.
“but it is the closest thing to a liger ever occurring in the wild.”
* That we know of.