You’ll possibly know of ligers from the movie “Napoleon Dynamite” (2004), in which a lad was obsessed with drawing them. Ligers are hybrid offspring from the cross of a male lion and a female tiger (the offspring of the reciprocal cross is called a “tiglon“). But you probably haven’t heard of—or seen—a liliger, which is the offspring of a hybrid female liger and a male lion. In genetic parlance, it’s the offspring of a hybrid backcross.
They breed the female hybrids because male ligers are sterile, conforming to Haldane’s Rule, named after geneticist J. B. S. Haldane, who first noticed this regularity. (H’s Rule is the generalization that if you hybridize two species and only one of the two sexes of offspring is sterile or inviable, that sex will almost invariably be the one having unlike sex chromosomes, or “heterogametic”. In mammals and my fruit flies, the hybrid males are XY [females xx] and thus are the susceptible sex, but in birds and butterflies it is the females who have unlike sex chromosomes and thus liable to be sterile or inviable as hybrids. I spent a lot of my career working on the genetic and evolutionary basis of Haldane’s Rule.)
According to the BBC News Europe, where you can find a short video (I can’t embed it), the liliger, named Kiara, has been adopted by the zoo’s resident cat because the mother can’t provide enough milk. That itself may be a deleterious symptom of hybridization. Although the film clip mentions criticisms of breeding such hybrids, saying they are of no conservational value and take up zoo space, I think they are of genetic and evolutionary value, for they tell us how well the genes of tigers and lions can cooperate in producing an offspring, and what maladaptive symptoms might arise from that hybridization. The data on hybrids between mammals, particularly ones as distantly related as lions and tigers, are still scant.
Here’s a screenshot from the video:
BTW, the common ancestor of lions and tigers lived about 3.7 million years ago. You can get this kind of information from the wonderful site TimeTree, where you can plug in any two species (including humans) and find out when their common ancestor lived, as well as the data used to determine that time. Your common ancestor with cats, for example, lived about 94.4 million years ago.