Melanism in the jaguar (Panthera onca) is conferred by a dominant allele, and in the leopard (Panthera pardus) by a recessive allele. Close examination of the color of these black cats will show that the typical markings are still present, but are hidden by the excess black pigment melanin, giving an effect similar to that of printed silk. This is called "ghost striping". Melanistic and non-melanistic animals can be littermates. It is thought that melanism may confer a selective advantage under certain conditions since it is more common in regions of dense forest, where light levels are lower. Recently, preliminary studies also suggest that melanism might be linked to beneficial mutations in the immune system.
The Javan leopard was initially described as being black with dark black spots and silver-grey eyes. Black leopards are common in the equatorial rainforest of Malaya and the tropical rainforest on the slopes of some African mountains such as Mount Kenya. They are also common in Java, and are reported from densely forested areas in southwestern China, Myanmar, Assam and Nepal, from Travancore and other parts of southern India where they may be more numerous than spotted leopards. One was recorded in the equatorial forest of Cameroon.
In captivity Edit
Melanistic leopards are the most common form of black panther in captivity and they have been selectively bred for decades in the zoo and exotic pet trades. According to Funk and Wagnalls' Wildlife Encyclopedia, captive black leopards are less fertile than spotted leopards, with average litter sizes of 1.8 and 2.1, respectively. This is likely due to inbreeding depression.
In the early 1980s, Glasgow Zoo acquired a 10-year-old black leopard, nicknamed the Cobweb Panther, from Dublin Zoo. She was exhibited for several years before being moved to the Madrid Zoo. This leopard had a uniformly black coat profusely sprinkled with white hairs as though draped with spider webs. The condition appeared to be vitiligo; as she aged, the white became more extensive. Since then, other "cobweb panthers" have been reported and photographed in zoos.
In jaguars, the melanism allele is dominant. Consequently, black jaguars may produce either black or spotted cubs, but a pair of spotted jaguars can only produce spotted cubs. Individuals with two copies of the allele are darker (the black background colour is more dense) than ones with just one copy, whose background colour may appear to be dark charcoal rather than black. The black jaguar was considered a separate species by indigenous peoples. W H Hudson wrote,
A black jaguar named "Diablo" was inadvertently crossed with a lioness named "Lola" at the Bear Creek Wildlife Sanctuary in Barrie, Ontario, Canada. The offspring were a charcoal black jaglionfemale and a tan-coloured, spotted jaglion male. It therefore appears that the jaguar melanism gene is also dominant over normal lion colouration (the black jaguar sire was presumably carrying the black on only one allele). In preserved, stuffed specimens, black leopards often fade to a rusty colour but black jaguars fade to a chocolate brown color.