The origin and migration of domestic cats: a genetic study

… articles about a new genetic study of domestic cats and their ancestor, Felis silvestris—an analysis published in a paper in Nature Ecology & Evolution by Claudio Ottoni et al.

The reference and free link to the paper (if you have “Unpaywall”) is at the bottom, as well as a link to the study’s supplementary material. The paper was also summarized in articles in The Guardian and in a Nature News and Views piece, and got tons of attention in the press because, well, cats.

In truth, the results can be summarized briefly; they’re a bit surprising but not earthshaking. First, if you want a video presentation and don’t want to read this whole post, just watch the 3.5-minute Nature synopsis below:

The authors looked at the mitochondrial DNA of 352 ancient cats from 30 archaeological sites, with samples taken from teeth, skin, and hair. They also looked at recent museum specimens of the five known subspecies of F. silvestris: the subspecies names are silvestris, lybica, ornata, cafra, and bieti. Here are their distributions with the numbers corresponding to the 30 archaeological sites sampled:

It’s been known from previous genetic studies that domesticated cats came from just one of these subspecies F. silvestris lybica (FSL), although modern housecats in Europe hybridize, and thus get genes from, the European subspecies F. silvestris silvestris (FSS). We also know, from remains of a cat associated with an ancient burial in Cyprus, that cats were at least semi-domesticated by 10,000 years ago, though they were probably not pets but living in association with humans and used for controlling rodents (there was agriculture by then, and stored grain needed protection). Here’s a rather skinny FSL, showing that the wild species is a striped (“mackerel”) tabby cat, but what’s shown below is a real wild species:

What the new study found, though, was that, using easily extracted mitochondrial DNA (mtDNA), there are five genetically distinct groups, or “clades”, within FSL. Using the distribution of these clades from dated cat remains from known locations showed how where cats were domesticated and how they moved about with the help of humans (probably largely on ships, which also have rodents).

 

Here are the five clades of mtDNA in FSL, also showing the genetic relationship of the other four subspecies with the inclusion if an outgroup species, Felis margarita, the adorable sand cat.

Here’s a sand cat just so you can see how cute they are. 

When the authors looked at the geographical distribution of these clades before domestication 10,000 years ago, they got the map below. Pay particular attention to the clades of FSL, as they are the ones used to trace the movement of cats in association with humans. A and B are in the Middle and Near East, and are genetically distinct from each other and from the DNA in clade C, which occurred (and still occurs) in North and Central Africa.

So looking at the genes of ancient cats from 10,000 years ago through Egyptian times and Roman times and medieval times to modern times, the authors found that the FSL subspecies appears to have been domesticated twice, It happened first in the Middle or Near East about 10,000 years ago, which we already knew, and then the descendants of those cats spread into southern Europe about 6000 years ago (we know this because cats from that region now carry the A and B mtDNA haplotypes seen above). Then there was another round of domestication that began in ancient Egypt about 4000 years ago. We know from ancient writings and artwork, as well as cat mummies, that the Egyptians kept tabby cats, and that their cats had the haplotype C from that region. Here’s an ancient painting from the Ottoni et al. paper showing an Egyptian tabby eating a fish under a woman’s chair. As the paper notes:

The image shows a ‘cat under the chair’ with a tabby mackerel marking, typical of F. silvestris lybica (Anna (Nina) Macpherson Davies, Copy of Wall Painting from Private Tomb 52 of Nakht, Thebes (I, 1, 99–102) Cat Eating Fish. Photo: © Ashmolean museum, Oxford, UK).

As shown by the correlation of clade C’s mtDNA with specimens from dated sites, the Egyptian-domesticated cats also moved into Europe, and in fact those Egyptian descendants became more numerous in Europe than did cats descended from the Middle and Near Eastern clades.  One of these Egyptian-like cats was also found at a Viking trading port, Ralswiek, on the Baltic sea, suggesting that cats were being moved around on Viking ships. Some of the Egyptian-clade domesticated cats even made their way to the region that’s now Iran, the domain of the wild subspecies Felis silvestris ornata.

So, based on mtDNA (and this needs confirmation with nuclear DNA, since mtDNA is really just a single gene that shows no recombination), cats in Europe are derived from FSL that was domesticated twice—in two places and thousands of years apart.

There’s one more interesting finding: the authors were able to get an idea about when humans began selectively breeding cats for coat patterns. (Cats probably largely underwent both natural and artificial selection for tameness, with the tamer wildcats able to get more food by approaching human settlements more closely, and then people breeding those cats that tended to hang around.)

There is one gene that is an indication of human selection for pattern: the gene causing the appearance of blotched rather than mackerel tabbies. As you see above, F. silvestris are mackerel tabbies in the wild, while the blotched pattern, seen below, is found only in domestic cats:

We also know that the difference between striped (“mackerel”) and blotched tabbies resides at a single gene, Taqpep (a “transaminopeptidase”), with the blotched form being recessive to mackerel (you need two copies of the blotched gene to get the blotched pattern). We also know the precise DNA sequences that code for either the mackerel or blotched pattern. The authors were able to get nuclear DNA sequences of this gene from about 90 cats, and ten of these had the blotched form, with this gene appearing earliest about 1400 AD.  Conclusion? Probably that, at least for coat pattern, people didn’t select cats for a preferred appearance until medieval times.

This is a very cool study, and course is especially interesting to us ailurophiles. What we need now are more data using nuclear rather than mtDNA (the latter tends to move more readily between populations), and, especially, samples from the Far East and elsewhere in the world, since all the samples studied came only from Africa, Europe, and the Middle and Near East. What happened in China? Were cats domesticated there 5,000 years ago, as one study suggests, and, if so, were they from F. silvestris ornata or F. silvestris bieti, whose ranges extend into the Far East? Time will tell, my cat-loving friends, but be assured that, given the big public interest in felids, we’ll have the genetic data soon.

______________

Ottoni, C., W. Van Neer, B. De Cupere, J. Daligault, S. Guimaraes, J. Peters, N. Spassov, M. E. Prendergast, N. Boivin, A. Morales-Muñiz, A. Bălăşescu, C. Becker, N. Benecke, A. Boroneant, H. Buitenhuis, J. Chahoud, A. Crowther, L. Llorente, N. Manaseryan, H. Monchot, V. Onar, M. Osypińska, O. Putelat, E. M. Quintana Morales, J. Studer, U. Wierer, R. Decorte, T. Grange, and E.-M. Geigl. 2017. The palaeogenetics of cat dispersal in the ancient world.  Nature Ecology & Evolution, doi:10.1038/s41559-017-0139

Supplementary information and data here.

 

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