Jerry is working on a Caturday felid post, but, as we all know, he is traveling in Antarctica, and thus the timing of its completion could be delayed. So, here are some felids for your Caturday fix! First up, a Siberian Tiger (Panthera, tigris altaica).
Siberian Tigers are the largest of the living cats, with body lengths (not including tail) exceeding 9 feet and weights exceeding 650 pounds. Like all tigers they are endangered, and occur in the Russian Far East and far northeastern China. I photographed this and the other cats during my vertebrate zoology class’s field trip to the Milwaukee Zoo, which I’ve already shown some penguins from.
A few years ago, zoos began calling Siberian Tigers “Amur Tigers”, the Amur River being the border between Russia and China. I’m not sure why zoos did this, but I see no reason to change the English vernacular name, since most English speakers know Siberia, but relatively few know what the Amur River is.
There was also a Lion (Panthera leo), a large male, also tight asleep.
Lions, as WEIT readers may know, were once widely distributed in southwestern Asia, and one population survives in the Gir Forest of northern India; the fellow above is one of the African subspecies.
The Zoo also has a Serval (Felis serval), another African cat, but ‘mid-sized’. I couldn’t get a good photo, but the vdeo gives you some idea of the appearance of this spotted cat. Note the short tail and large ears. His name is Amos.
I also saw one of the Zoo’s Jaguars (Panthera onca), but couldn’t get a good picture. This is not a great shot of their two Cheetahs (Acinonyx jubatus), either– they were outdoors, and fairly far away. But they seemed so relaxed, I decided to post it anyway.
Cheetahs, like Lions, were once widely distributed in Africa and Asia. The Asian Cheetah was thought extinct, but was documented to still exist by camera-traps in Iran.
On this visit, I paid closer attention to the Zoo’s ‘big cat kitchen’, which is visible through a window, than I have on previous occasions.
I’ve visited the kitchen at the Racine Zoo. Not visible in this photo, but an important part of the kitchen’s tools from what I’ve seen in Racine, are the big knives used for cutting up the prepared diets, and the special protective gloves the keepers wear to protect their hands and fingers when doing so. There were two commercial diets visible on the counter: Toronto Zoo Feline Diet (which is horse meat, I believe)
Also visible in the kitchen is a board which displays the daily ‘menus’ for each cat, along with their names. (That’s how I know the Serval is Amos. The male Lion must be Themba, the Siberian that I photographed is probably Kashtan, and both Cheetahs, Kira and Imara, are in the picture, but I don’t know which is which.) So, just as Jerry has been sharing his shipboard menus, here are the cat menus– click to enlarge!
Our felid for today is actually five felids: a mackerel (striped) tabby, a blotched tabby, a spotted cheetah, a king cheetah and a black-footed cat. In a new paper in Science by Christopher Kaelin and colleagues, the physiological basis of these pattern variations in both domestic cats and cheetahs is shown to be due to mutations at the Transmembrane aminopeptidase Q locus (Taqpep for short ) that alter the function of its encoded protein, which they call Tabulin.
It has long been known that the dark areas in a tabby’s coat are places where the hairs are colored mostly by eumelanin (a darker pigment), while the hairs of the lighter areas have more phaeomelanin (a lighter pigment). In both areas, the individual hairs have bands of color (look closely at your cat’s hairs: you’ll see that few are unicolored– most are banded in some way). In mackerel tabbies, the dark and light areas are arranged in a periodic pattern, creating tiger-like stripes. This is the pattern found in the wild cats that are the domestic cat’s progenitors, and is still one of, if not the, most common patterns in domestic cats.
It has also long been known that the blotched tabby condition is due to recessive alleles at an autosomal (i.e., non sex-chromosomal) locus, called Ta, so that having two copies of the mutant allele b makes the tabby blotched. What Kaelin and colleagues have done is show that the Ta locus is in fact the gene Taqpep. In domestic cats, blotched tabbies have one (or more) of three single nucleotide mutations that alter the Tabulin protein’s function. If you have one copy of the dominant (M) allele, you’re mackerel (see diagram above).
One of the coauthors of the paper is Ann van Dyk, who, back in 1986, with R.J. van Aarde, first definitively demonstrated that king cheetahs, at one time thought to be a different species and the object of much cryptozoological speculation, were in fact a color-pattern variant of the common cheetah, with the same mode of inheritance as the blotched tabby: an autosomal recessive gene.
In the new paper Kaelin et al. extend their work to cheetahs, sequencing their Taqpep genes, and found that in king cheetahs there is a single base pair insertion in the gene that causes a frameshift, a type of mutation that alters every amino acid encoded downstream in the gene from the site of the insertion. Thus the king and blotched patterns result from alterations of a homologous gene, but the mutations themselves are not identical, being caused by a single nucleotide substitution in domestic cats but by an insertion in cheetahs.
Kaelin et al. also sequenced the Taqpep locus in 29 other species of wild cats, assessing any nonsynonymous substitution (i.e., those that change the amino-acid sequence of the protein produced by the gene) for how likely they were to alter protein function. All the cats had “normal” genes, except for the black-footed cat (Felis nigripes), which had five substitutions that were collectively judged as being very likely to alter the protein’s function. Interestingly, the black-footed cat has a pattern similar to domestic cats with a “swirled” pattern associated with the mutation T139N of the Taqpep locus:
Kaelin et al. note that blotched tabbies rarely appear in early illustrations of cats, but that by the 18th century they had become more common. They also note that there is a fairly large region (244kb of nucleotides) around the Taqpep locus that is invariant in blotched tabbies, while it has usual levels of variability in mackerel tabbies. This is the exact pattern, both historically and genetically, that we would expect if the blotched pattern had been favored by (presumably artificial) selection over the last few hundred years.
When an allele is favored by selection, closely linked forms of genes will also increase in frequency (a phenomenon known as “hitchhiking”), leading to higher frequency or fixation for a whole block of genetic material. Recombination will eventually break up the association of the favored and hitchhiking alleles, and new mutations will increase variability; but this dissociatio takes time, and until it happens the region of low variability persists as a record of the selection (which in this case may still be ongoing).
[Note by GCM: While the paper, at five pages, is long by Science‘s standards, there are still 27 pages of online supplements, and it is difficult to follow the authors’ train of argument and evidence since it requires constant switching between the paper and the appendices to fully appreciate what they’ve done (not to mention it would be impossible to do so if you were reading the journal or a reprint, rather than an online version). More justice would have been done to the authors’ work, and to their readers, had a substantially longer paper been published (which, of course, could not have appeared in Science). I mention this not to criticize the authors, but to decry the increasing practice of putting essential parts of a paper into relatively inaccessible and, I fear, ephemeral, appendices.]
Kaelin, C. B., X. Xu, L. Z. Hong, V. A. David, K. A. McGowan, A. Schmidt-Küntzel, M. E. Roelke, J. Pino, J. Pontius, G. M. Cooper, H. Manuel, W. F. Swanson, L. Marker, C. K. Harper, A. van Dyk, B. Yue, J. C. Mullikin, W. C. Warren, E. Eizirik, L. Kos, S. J. O’Brien, G. S. Barsh, and M. Menotti-Raymond. 2012. Specifying and sustaining pigmentation patterns in domestic and wild cats. Science 337:1536-1541. abstract
van Aarde, R.J. and A. van Dyk. 1986. Inheritance of the king coat colour pattern in cheetahs Acinonyx jubatus. Journal of Zoology 209: 573-578. pdf
The king cheetah, known only from southern Africa, is a striking pattern variation of the common cheetah (Acinonyx jubatus). Instead of being spotted, the dark markings of the king cheetah coalesce into stripes and vermiculations, especially along the dorsal midline. King cheetahs are to common cheetahs as blotched tabbies are to spotted tabbies, not just in the similarity of the patterns, but in their genetic relationship: the king pattern is a variation within populations of the same species, and both patterns can occur in the same litter.
In 1927, R.I. Pocock of the British Museum named the king cheetah as a new species, Acinonyx rex, the holotype being a specimen at the Queen Victoria Memorial Library and Museum in Rhodesia (now Zimbabwe). In 1932 the zoologist Angel Cabrera suggested that the king cheetah was merely a coat pattern variant of the common cheetah. For many decades after that the question of the status of the king cheetah was unresolved, as few specimens were known, and genetic experiments on cheetahs not possible. Cryptozoologists became interested in the king cheetah as a ‘semi-cryptid’– a not quite undiscovered species of large mammal, but at least a mysterious one.
In the 1970s more king cheetahs turned up, and methods of captive breeding of cheetahs, developed for conservation purposes, had advanced to the point where it was possible to investigate the question. In 1986, R.J. van Arde and Ann van Dyk of Pretoria University and the National Zoo in Pretoria, South Africa, showed that the king coat pattern was due to a recessive mutation at a single autosomal locus, thus vindicating Cabrera’s hypothesis from 50 years earlier. King cheetahs are now found in several animal parks in South Africa, and can be easily seen and photographed.
The story of the king cheetah shows that even when a new species is described and named according to the best practices, including insuring a publicly available holotype, it doesn’t guarantee that the species so named is new. It might be a new species, but it might also be a geographic or within-population variation of a known species (the latter in the case of the king cheetah), or in some cases nothing new at all (as when the describer is unaware that a description had been published previously).
We all know that cheetahs are fast, but I didn’t know they were this fast: over 60 mph, and some say over 70. That is three times the speed ofUsain Bolt, the world’s fastest man,when he ran his world-record 100 meter dash. Imagine: by the time Bolt made it from the blocks to the finish line, the cheetah could run that distance, run back to the blocks, and then sprint to the finish line, drawing even with Bolt. A new piece on the BBC website discusses recent work on cheetahs, with a nice video showing how they’re studying the running animal, making it run after a piece of chicken on a string, much like greyhounds run after a mock rabbit. (It’s not really clear what the researchers are actually trying to find out.)