The liger is a hybrid between a male lion (Panthera leo) and a tigress (Panthera tigris). It exists only in captivity, and no wild liger has ever been confirmed.[1] Ligers are best known for their size, but they are rare, zoo groups say they have no conservation value, and breeding them is banned in the United States.[1][2]
Parents
A liger has a lion father and a tiger mother. The reverse cross, a tiger father and a lioness mother, is called a tigon.[1][3] Lions and tigers lived in the same parts of Asia in the past, and their ranges overlapped several times, but no wild hybrid has been reported.[4]
Appearance
Ligers are usually tawny with faint tiger stripes and spots, and males can grow a sparse mane.[5] The largest on record is Hercules, which Guinness World Records listed in 2013 as the largest living cat. It weighed 418.2 kg and measured 3.33 m in total length.[6]
One proposed reason for the size is genomic imprinting, in which genes inherited from the father push growth and genes from the mother hold it back. A liger would inherit the strong growth drive of a lion father without the matching restraint from a tigress.[7] The idea comes from studies of hybrid mice, in which reciprocal crosses grow very differently.[8] No study has measured imprinting in a liger or a tigon, so it remains a hypothesis.[7]
Fertility
Female ligers can breed. In 2012 a liger at Novosibirsk Zoo in Russia was reported to have produced a cub with a lion, called a liliger, which National Geographic said might be the only one in existence.[9] Male hybrids are expected to be sterile, a pattern called Haldane’s rule, in which the sex with two different sex chromosomes is the one affected.[3][10] No fertile male liger has been documented.[1]
History
A hobbyist compilation of historical records says cubs of a lion and a tigress were shown to King George IV at Windsor in 1824, and that a travelling menagerie raised six litters between 1824 and 1833. These accounts come from 19th-century writers and were not checked against the originals.[5]
Law and ethics
In the United States, the Big Cat Public Safety Act of 2022 makes it unlawful to breed or possess any lion, tiger, leopard, cheetah, jaguar or cougar “or any hybrid of such species”. Licensed exhibitors, universities, qualifying sanctuaries and animals owned before the law are exempt.[2] The Association of Zoos and Aquariums has said that hybrids have no conservation value and give a confused educational message.[1] How common health problems are in big-cat hybrids is not known.[1]
Sources
- National Geographic, 24 February 2017, on ligers and other big-cat hybrids
- Big Cat Public Safety Act, Public Law 117-243 (2022)
- Li et al. 2016, Genome Research 26: 1–11 (ancient hybridisation in cats)
- Schnitzler & Hermann 2019, Mammal Review 49: 340–353 (lions and tigers in Asia)
- Messybeast, ligers and tigons (hobbyist site with dated quotations; secondary)
- Guinness World Records, largest living cat (2013)
- Messybeast, growth dysplasia in hybrids (hobbyist account; a hypothesis only)
- Vrana et al. 2000, Nature Genetics 25: 120–124 (imprinting in hybrid deer mice)
- National Geographic, 21 September 2012, on the liliger
- Haldane 1922, Journal of Genetics 12: 101–109 (hybrid sterility)