Ligers are the offspring of lions and tigers, the result of species interbreeding in a closed environment like a zoo, or through artificial insemination. Sleek and muscular, with tawny, lion-like pelts adorned with faded tan tiger stripes, ligers are the aristocrats of the feline world. Lounging in their zoo habitats, they look somewhat like giant house cats. In fact, ligers are the largest of the Panthera genus, 100 times larger than the average domestic feline. How big is big? Ligers have been known to grow twice the size of their parents.
The Genetics of Lion and Tiger Mating
Why the super-size? According to Sarah Hartwell of Messybeast.com, in an article entitled "Why Are Ligers So Much Bigger Than Tigons?", it comes down to genetics. Lions are social, and live in prides. When in heat, a lioness may mate with two or more males. The lions’ genes have different goals. The males want their offspring to survive and thrive over their rivals’ offspring, so their genes are programmed towards size and strength. The lioness, however, wants all the unborn cubs to survive. Her genes tend to level the playing field, inhibiting growth to give all her offspring a better chance at survival.
Tigers are different. They’re loners, and a tigress usually takes only one mate. Gene competition between males is not a factor, so there’s no need for a gene encouraging larger cubs. The tigress’s checks and balances aren’t needed, so her cubs can grow uninhibited.
Growth Dysplasia Makes Ligers Bigger Than Lions
But a lion’s strategy leans towards competitive breeding. His genes insist on promoting that large-offspring agenda. When he mates with a tigress, her genetic programming won’t inhibit their cub’s growth. Their offspring (a liger) will grow bigger and stronger than the parent stock. Much bigger. This imbalanced assertion of growth-control genes, inherited from either the male or female, is called ‘genomic imprinting’. In the case of the lion-tigress romance, the result is ‘growth dysplasia’ – the super-sized liger.
Here’s a test. Will a tigon (the offspring of a male tiger and a lioness) grow as large as a liger? If you said no, you’re correct. The tiger’s genes have no growth-promotion strategy, but the lioness’s genes are still compensating, inhibiting growth. In this case growth dysplasia is manifested as a tigon smaller than either parent – essentially a dwarf.
Genomic imprinting is one theory of why ligers grow large (or tigons stay small), but there are competing theories. The truth is, the cause of growth dysplasia is still not fully understood.
Celebrity Liger
One magnificent liger has reached celebrity prominence - Hercules, the headline attraction at The Institute of Greatly Endangered and Rare Species (T.I.G.E.R.S). The Guinness Book of World Records lists Hercules is “the Largest Cat on Earth”. He weighs in at over 900 pounds. Think three sumo wrestlers sharing a twin bed. Standing on his hind legs, he’s taller than an NBA player dunking the ball – around 12’. He’ll eat close to 25 pounds of meat at a sitting. He could eat more, but overeating causes obesity. His trainers regulate his nutritional intake by feeding him a special potpourri of horse, cow, chicken and pig parts called King Lion Diet, blended together and formed into a loaf – a meal truly fit for a king.
Ligers continue to be born in captivity, but usually by accident, when a tiger and a lioness find themselves in close proximity. Occasionally an organization might use artificial insemination to purposely create a liger, but the Association of Zoos and Aquariums states that accredited zoos don’t follow that policy.
Take your family to see a liger. There’s nothing like a face-to-muzzle meeting, with only a flimsy barrier between cat and human, to reinforce their size. Whatever their origin, big, beautiful ligers will continue to fascinate us, staking their claim – their huge claim – on the hearts of animal lovers everywhere.
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