Monday, 21 April 2014

GENETICS: MUTANT BIG CATS - SPOTTED LIONS

Mutants are natural variations which occur due to spontaneous genetic changes or the expression of recessive (hidden) genes. Recessive genes show up when there is too much inbreeding. White tigers and white lions are uncommon in the wild as they lack normal camouflage. Albinism (pure white), chinchilla (white with pale markings) and melanism (black) are the commonest mutations. Erythristic (red), leucistic (partial albinism/cream) and maltesing (blue) are also been reported. Sometimes the markings are aberrant e.g. too sparse or too heavy (abundism), giving the appearance of a pale or dark individual. White, black, red, blue or cream mutations are similar to those found in domestic cats. Sometimes the pattern is different from normal e.g. the blotched King Cheetah or an normally coloured individual may have anomalous black patches (mosaicism) or white patches (partial albinism). Rufism refers to the richness of the red colour in tawny-coated cats.
As well as anomalous colours, there are abnormally large or small individuals, longhaired individuals, short-tailed or even tail-less individuals. All of these occur in domestic cats so why are they less common in big cats? Wild cats displaying these traits may be less likely to survive to pass on the traits. In captivity, humans control which traits are bred, hence the multitude of domestic cat colours and types. In the wild, nature selects against any trait which does not enhance the animal's survival chances.
In the past, the obvious reaction to any unusual big cat was to shoot it for the trophy room. As a result, many interesting mutations may have been wiped out before the genes were passed on. Some colour mutations which would disadvantage a wild big cat are bred in captivity and are not viable in the wild. It is questionable whether these mutants should be perpetuated for the sake of curiosity 
SPOTTED LIONS
Lion cubs are spotted or rosetted for camouflage. They normally lose their spots when they reach adulthood. There are numerous sightings of spotted lions and a number have been shot and the pelts displayed. Young adult lions often have markings which are clearly visible in certain light and some retain strong markings. There is also the less likely explanation that the spotted lions are leopons - lion x leopard hybrids. These have been bred in captivity although the leopard is much smaller than the lioness. There are African legends of naturally occurring leopons and there has been one report of a solitary lioness accepting a leopard as a mate and producing hybrid cubs. In the wild, this would only occur where a lioness is unable to find a male of her own species. The spotted lion, where there is good contract between the spot colour and the background, probably represents a natural variation.
When suggesting that the marozi is a lion-leopard hybrid it is necessary to understand that a person describing it as "a cross between lion and leopard" may simply mean it bears resemblance to both of those creatures and does not mean it is literally a hybrid.
The first observations of spotted lions (marozi, Panthera leo maculatus) by westerners were made by Colonel Richard Meinertzhagan in 1903 when he described darker lions with rosette-like markings in the Kenyan mountains. Meinertzhagen had heard of the marozi several times between 1903 and 1908, but no official notice was taken of it and it was probably dismissed as native myth.
In 1924, Captain A Blayney Percival, renowned game warden and brilliant naturalist (in the days when this meant shooting things!), reported killing a lioness and her cubs which were all very clearly spotted. The lioness was described as being no less spotted than her cubs. It was possible some individuals retained their juvenile spotting much later than usual. The existence of cubs is often cited as evidence that the spotted lioness could not have been a leopon hybrid. However, female big cat hybrids are often fertile, producing offspring if mated to a non-hybrid big cat. It is the male hybrid that is sterile.

In 1931 Captain RE Dent, Kenyan game warden in charge of the Fisheries section, observed 4 spotted lions crossing the path in front of him, between 10,000 and 11,000 feet up, near the source of the Kathita above Meru. These lions seemed darker and smaller than normal lions and "of a very different type". Dent seemed to forget about them until a few months later when his boys, who had set leopard-traps all along the eastern slopes of the Aberdare Range, excitedly told him that they had caught an unusual animal that was neither a lion nor leopard, but some sort of cross between the two. For some unknown reason they were unable to bring the specimen back and had not preserved the skin of this spotted lion.or aesthetics alone.An Irish adventurer and author of the book "Nomad" (1934), C.J. McGuinness, wrote that Carl Hagenbeck (animal collector for Hamburg Tierpark and breeder of many big cat hybrids) had himself sighted a spotted lion.
There were also reports of a spotted lion being trapped and killed around 1931. The main evidence comes from skins obtained in 1931 when Michael Trent, a white farmer in the Aberdare Mountains of Kenya, shot 2 small lions, one male and one female with strange fur. They had been attracted to a waterbuck fixed as bait some 10,000 up in the Aberdares. Trent was not a naturalist and took little notice of their odd appearance, but preserved the skins as trophies. The skins later caught the attention of an official in the Game Department who considered them unusual enough to be taken to Nairobi to Chief Game Warden Captain ATA Ritchie. The skins were examined by Game Department officials in Nairobi and Ritchie recognised that they were unusual.
The skins belonged to a lion and a lioness, though the mane on the male's skin consisted of little more than side-whiskers. From their size they seemed to belong to lions at least 3 years old (i.e. of pubescent age) and were probably a lion and his mate. Unusually, the skins were spotted although lion cubs normally lose their juvenile spotting well before 3 years old. The skins were clearly spotted, and the spots showed no signs of fading. Lacking a complete skeleton, or at least a skull, which could have definitely established the specimen's age (and probably species), it was hard for the Game Department officials to give a verdict.
Kenneth Gandar Dower, a big-game hunter, examined Trent's skins and wrote: "They appear to belong to lions two or three years old – the male had a whiskery mane – and yet the cub spots with which almost every lion is born showed no signs of fading. Certain freak lions do keep their spots to an advanced age, but not in a degree comparable with these rosettes which were distributed not only on the legs and flanks, but right up to the spine itself."
This, along with Blayney Percival's spotted lioness shot in 1924, convinced Gandar Dower that a separate species of spotted lion existed and in 1933 he, accompanied by the more sceptical Raymond Hook, organised a safari to look for specimens. In his safari book "The Spotted Lion" (1937), the 26 year old African adventurer Gandar Dower wrote: "Mine was not a promising situation when I found myself stranded in Nairobi. My only assets were a love of Rider Haggard and a vague half-knowledge of what I wished to do. I wanted to see big game in their natural surroundings, to take their photographs, and, once that was done, to fit myself to go alone into the great forests. I wanted to discover and to explore. Yet I could not speak Swahili. I had no fiends in Kenya. I had scarcely taken a still photograph (that had come out) or fired a rifle (except upon a range). My riding was limited to ten lessons, taken seventeen years previously when I was nine, on a horse which would barely canter. My shy suggestions of the possibilities of new animals brought only rather scornful jokes about the Naivasha Sea Serpent and the Nandi Bear. [...] This opportunity, given so undeservedly to a novice, who three months ago had never been to Africa or really ridden a horse or fired a rifle at a living thing, was almost too great a responsibility to bear. I felt small. Even with Raymond's help, how could I hope to find this rare animal, the very existence of which had for so long been unsuspected, in 2000 square miles of wilderness, through which we could hardly travel, to find it and track it down, and read more

No comments:

Post a comment