Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
by Greg Mayer
As an extra bonus felid for today, and continuing the theme of cat coat patterns as camouflage, here’s the snow leopard (Panthera uncia).
You can’t see the snow leopard or it’s pattern very well, but, of course, that’s the point. Its head is to the right.
(BTW, is anyone getting the Monty Python reference?)
by Greg Mayer
Jerry recently posted about a new analysis of cat coat color patterns by William Allen and colleagues from the University of Bristol that is in press in The Proceedings of the Royal Society B, so I thought it might be interesting to take a look at one of the species in the analysis, that I was able to photograph recently: the jaguar, Panthera onca.
It kind of looks like he’s about to spring and make a meal of me, but I didn’t take the picture in a tropical American forest, but at the Milwaukee County Zoo. Jaguars are of course spotted cats, with dark rosettes on a lighter background. Leopards (Panthera pardus), found in Africa and Asia, are rather similar, but jaguars have a dot in the middle of many of the rosettes. Jaguars also have a relatively larger head and more muscular forequarters, which are also noticeable in the next picture.
As Jerry noted in his post, Allen and colleagues found that spotted patterns were significantly associated with closed or forested habitats. The jaguar is a bit of a problem in this regard, as it is a habitat generalist, found in the semi-desert of the southwestern US and northern Mexico, as well as in Neotropical rainforests. The authors attempted to account for varying degrees of habitat usage and specialization, although they did apparently miss the jaguar’s occurrence in semi-desert.
by Greg Mayer (update below)
Pedro Reis of MIT and colleagues are about to publish a paper in Science analyzing high speed films of cats drinking. A preprint is already available. I’m not sure there’s really anything interesting here, other than cool video. You can tell that only the tip of the cat’s tongue contacts the milk, so the ‘brushy’ part of the cat’s tongue is not involved in getting milk into the mouth, which is not what I would have expected. (The brush has a large surface area, which I thought would be involved in liquid adhesion, but it’s not.)
There are more videos at Reis’s website, here and here. Ed Yong at Not Exactly Rocket Science has more background on the work, and notes that MIT’s Harold ‘Doc’ Edgerton (of Loch Ness monster fame) made high speed film of cat lapping in 1940. The cat is at about 4:41.
Edgerton (or at least his film’s narrator) thought the back of the tongue cupped the milk, but Reis’s better films show the milk is on the front of the tongue, not the back, curled part of the tongue. The BBC also has a story up.
P.M. Reis, S. Jung, J. Aristoff and R. Stocker. 2010. How Cats Lap: Water uptake by Felis catus. Science in press.
Update. MIT has a press release with more background available here. I mentioned that cats don’t ladle the milk, nor is it the brushy part, and I’ve been queried about what it is they do do. Here’s how the MIT press release puts it:
Cats, unlike dogs, don’t dip their tongues into the liquid like ladles. The cat’s lapping mechanism is far more subtle and elegant. The smooth tip of the tongue barely touches the surface of the liquid before the cat draws its tongue back up. As it does so, a column of liquid forms between the moving tongue and the liquid’s surface. The cat then closes its mouth, pinching off the top of the column for a nice drink, while keeping its chin dry.
When the cat’s tongue touches the liquid surface, some of the liquid sticks to it through liquid adhesion, much as water adheres to a human palm when it touches the surface of a pool. But the cat draws its tongue back up so rapidly that for a fraction of a second, inertia — the tendency of the moving liquid to continue following the tongue — overcomes gravity, which is pulling the liquid back down toward the bowl.
The release goes on to mention that the cat instinctively knows when to close its mouth, but the paper did not in fact address that question, and cats may well learn the timing (much as first basemen learn the perfect time to snap their glove shut). The NY Times has a story up now too. Besides the cool video, the most interesting thing to me about the paper is that they were able to predict a relationship between lapping frequency and body mass, and show that their prediction roughly held (see Fig 4c of the paper; the authors make only a glancing reference in the text).
Displaying Steve Pinker’s rudimentary moral sentiments not just toward their human companions, but toward one another, these goggies and kittehs show that Bill Murray’s disaster of Biblical proportions is upon us. Or maybe that we can all just get along.
by Greg Mayer
Of interest to both ecological geneticists studying vertebrate polymorphisms and cryptozoologists is the king cheetah.
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).
by Greg Mayer
One of the most enigmatic of the felids is the spotted lion. Indeed, it’s so enigmatic that it might, in some senses, be said to not even exist.
As you may recall from Jerry’s earlier posting of a video of lion cubs, lions are born with spots, which disappear as they mature. Jerry and I disputed whether such patterns in young animals are atavistic or adaptive, but my concern today is not with whether spots are adaptive, but whether there are spotted lions at all.
The photograph above is the best evidence we have for the existence of spotted lions. (The skin’s total length is 8 ft. 8 in., so it’s not a cub!). I’ve previously noted that photographs are not the best evidence for documenting the existence of a previously unknown species of animal, but in this case we have the benefit of the fact that the specimen in the photograph was examined by Reginald Pocock of the British Museum (Natural History) in the 1930s. Here is some of what Pocock, a world authority on cats, had to say, about the specimen loaned to him by Kenneth Gandar Dower (subscription required):
…it is a remarkable specimen owing to the distinctness of the spots in a beast of its size.
It is a male. … From it’s size I guessed it to be about three years old, a year or more short of full size.
…the peculiarity of the skin lies in the distinctness of its pattern of spots, consisting of large “jaguarine” rosettes arranged in obliquely vertical lines and extending over the flanks, shoulders and thighs up to the darker spinal area where they disappear.
As is well known, lion-cubs at birth generally, but not always, show a pattern of spots or stripes supposed, probably correctly, to be the remnants of an ancestral pattern transmitted from the time when lions were denizens of forests or jungles. In nearly all cases this juvenile pattern vanishes at three or four months on the body, but persists longer on the belly and legs and may sometimes be visible on those parts at maturity, especially apparently in sone lionesses from East Africa. Mr. Gandar Dower’s lion-skin is quite exceptional in this respect.
Pocock went on to indicate the absence of this pattern in a large series of adult specimens at the British Museum and the United States National Museum, but noted one account and one photograph that indicated at least an approach to being spotted. He also examined a skull provided by Gandar Dower, which may have come from this specimen, or from a female shot at the same time; the skulls were not kept when the animals were skinned, but one was retrieved later. Pocock concluded
…it is clear that no precise conclusion can be formed regarding this interesting beast until skins and skulls of adults have been collected.
As noted above, the skin was brought to Pocock by Kenneth Gandar Dower. Gandar Dower had read accounts of the spotted lion and mounted an expedition to East Africa to try to find one, but was unsuccessful, save for the skin and skull which he obtained from Michael Trent, a farmer in the Aberdare Mountains of Kenya, who had shot a pair of spotted lions a few years earlier. Gandar Dower recounted his expedition in a book, The Spotted Lion. Bernard Heuvelmans summarized Gandar Dower’s investigations, and recounted later stories of the spotted lion in his On the Track of Unknown Animals.
So what is the spotted lion? There are several possibilities. First, it might represent a distinct population that lives in the Aberdare Mountains of Kenya. In this case, it might be a species distinct from other lions, or it could be a geographical race or subspecies of the familiar lion. Second, it could just be a rare individual variation, in the same way that populations of house cats have spotted, striped, particolored, solid, etc. patterns occurring in individuals that are part of the same breeding population (and, indeed, part of the same litter). Finally, it could be a hybrid, perhaps between a lion and a leopard. Pocock, however, was well familiar with interspecific hybrids in large cats, and did not mention this possibility; also, interspecific hybridization in large cats is known (almost?) exclusively among captive animals. So, a hybrid origin does not seem likely to me.
If the first possibility is true, then there would indeed be something we can rightfully call the spotted lion. If the second is true, while there would then be known to exist lions with spots, there would not be a distinct natural population. And if the third is true, then there aren’t spotted lions at all– only lion-leopard hybrids that have spots. Further study of the skin or supposed skull, especially using modern techniques, might have allowed at least some of the possibilities to be eliminated, but unfortunately, Pocock apparently did not retain them at the British Museum, and I am unaware of their current whereabouts. (I had thought they were at the British Museum until reading Pocock’s full account, in which he notes the specimens were left for him to examine, but makes no mention of them being donated to the collection.) To solve this problem, we thus must, as Pocock did over 70 years ago, await the collection of more specimens.
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Gandar Dower, K. 1937. The Spotted Lion. Little Brown, Boston.
Heuvelmans, B. 1959. On the Track of Unknown Animals. Hill and Wang, New York.
Pocock, R.I. 1937. Note on the spotted lion of the Aberdares. pp. 317-321 in Gandar Dower, 1937.
by Greg Mayer
Following some links from PZ, I ran across this website: Skepticcat. It’s got cats and skepticism. Sample text:
If LOLcats ebolbed from tigers den y r there still tigers?
Sample image:
[The lolcat is a comment on Pat Robertson saying that the Haitian earthquake is Haiti’s just desserts for its sinful past (2 posts). Robertson’s abysmal ignorance is signalled by, among other things, his saying that Haitian independence was won from Napoleon III, who wasn’t born until 4 years after the successful end of the Haitian war of independence, while his moral decrepitude is signalled by his main claim. On this matter, see also PZ, Andrew Sullivan, Ta-Nehisi Coates (2 posts), and Rachel Maddow (2 posts).]