Classic, mackerel, spotted or ticked - tabbies represent some of the most stunning coat patterns in the feline world.
The understanding of the genetics of the various tabby patterns has evolved over the years, with various theories of inheritance being confirmed or proven incorrect as science has been able to discover and map the genes involved.
New research results published in late 2009 in the journal Genetics, a publication of the Genetics Society of America, has clarified the inheritance of tabby patterns.
Below is an abstract of the researchers findings:
Defining and Mapping Mammalian Coat Pattern Genes:
Multiple Genomic Regions Implicated in Domestic Cat Stripes and Spots
Eduardo Eizirik,* Victor A. David,* Valerie Buckley-Beason,*,2 Melody E. Roelke,B' Alejandro A. Schaffer,** Steven S. Hannah, Kristina Narfstrom, Stephen J. O'Brien* and Marilyn Menotti-Raymond*
Mammalian coat patterns ( e.g ., spots, stripes) are hypothesized to play important roles in camouflage and other relevant processes, yet the genetic and developmental bases for these phenotypes are completely unknown.
The domestic cat, with its diversity of coat patterns, is an excellent model organism to investigate these phenomena.
We have established three independent pedigrees to map the four recognized pattern variants classically considered to be specified by a single locus, Tabby ; in order of dominance, these are the unpatterned agouti form called "Abyssinian" or "ticked" (T a ), followed by Spotted (T s ), Mackerel (T M ), and Blotched (t b ).
We demonstrate that at least three different loci control the coat markings of the domestic cat.
- One locus, responsible for the Abyssinian form (herein termed the Ticked locus), maps to an 3.8-Mb region on cat chromosome B1.
- A second locus controls the Tabby alleles T M and t b , and maps to an 5-Mb genomic region on cat chromosome A1.
- One or more additional loci act as modifiers and create a spotted coat by altering mackerel stripes.
On the basis of our results and associated observations, we hypothesize that mammalian patterned coats are formed by two distinct processes: a spatially oriented developmental mechanism that lays down a species-specific pattern of skin cell differentiation and a pigmentation-oriented mechanism that uses information from the preestablished pattern to regulate the synthesis of melanin profiles.
So, what does this all mean in English? <g>
Basically, there are 3 different and separate genes that control the tabby pattern in our cats.
The first gene, which is dominant, is for the Ticked Tabby (ie Abyssinian, Singapura, etc). This gene is abbreviated by a notation of "Ta". If a cat has this gene, they will show as a ticked tabby, regardless of any of the other tabby genes they may have.
The second gene comes in to play if the "Ta" gene is not present, and controls the tabby pattern, either Mackerel or Classic (also called blotched). These genes are noted as TM (mackerel) and tb (blotched), and as indicated by the upper/lower case of the notation, the mackerel gene is dominant, the classic/blotched gene is recessive.
The third and final gene is a modifier gene, and also only comes in to play if the "Ta" gene is not present. This gene, noted as Ts, is called the spotting gene, and breaks up the lines of the tabby pattern (mackerel or classic) into spots. The overall pattern of mackerel or classic is still maintained.
To learn more about the interesting subject of tabby genes and tabby gene inheritance,