From the readers’ comments on yesterday’s cat-coat post, there’s clearly some interest in the genetics and evolution of house cats (Felis catus). This is a huge topic, too large to cover here (in my younger and impecunious days, I thought of writing a popular book on the topic). I just want to make two points:
1. We know an enormous amount about the genetics of cat coat color and pattern. Wikipedia, for instance, has a good summary, and if you want a dose of photos with your genetics go here. Note that much of what was written about the genetics of ticking and tabby patterns before this year is likely to be wrong: a recent paper by Eizikir et al. (2010) shows that there are at least three loci responsible for the variation (everybody used to think that there was one), and probably at least two developmental pathways involved in producing the familiar patterns of spots, stripes, and swirls.
Here’s a nice photo from their paper showing a cross between two parents (“P”), their offspring (F1), and the backcrosses, obtained by crossing F1 individuals to one of the parents. Note the re-establishment of the striped “mackerel” pattern in the backcross offspring. These crosses helped Eizikir et al. disentangle the genetic interactions involved in coat pattern.
2. Why is there such variety in the coats of domestic (and stray) cats? Surely because people have bred for those colors and patterns, and most feral cats are recent descendants of pets.
It’s my theory that all feral cat populations will eventually revert to the tabby pattern; this comes from observing long-time populations of strays, and seeing the pattern of the “Scottish wildcat”, which I firmly believe is not a native species but a descendant of feral domestic cats. (Populations of feral dogs seem to revert to a yellowish, dingo-like color.) Why this reversion, if it’s indeed the case? Perhaps selection for camouflage, although I’m not sure what preys on feral cats, and whether those cats live in habitats where a tabby pattern would camouflage them to both predators and prey. Another explanation is that the tabby pattern is linked to genes that help domestic cats survive when forced to live ferally.
Eizirik, E., V. A. David, V. Buckley-Beason, M. E. Roelke, A. A. Schaffer, S. S. Hannah, K. Narfstrom, S. J. O’Brien, and M. Menotti-Raymond. 2010. Defining and mapping mammalian coat pattern genes: Multiple genomic regions implicated in domestic cat stripes and spots. Genetics 184:267-275.