Cats that have only longhair genes or only shorthair genes are said to be homozygous for that trait. The beautiful longhaired Persian cats, for example, are homozygous because they must possess two longhair genes before the recessive longhair trait can express itself. Consequently, Persians, when bred to other longhairs, always produce longhaired offspring.
Mutations
Occasionally, genes go haywire as nature attempts to improve upon itself or create something new and better suited to the environment. Aside from color variations, genetic mutations are also responsible for other distinctive characteristics certain breeds bear, such as the folded ears of the Scottish Fold, the stubby tail of the Manx, the hairless coat of the Sphynx, and the soft, curly coat of the Devon Rex and the Cornish Rex. Selective breeding has preserved these mutant traits that under random conditions likely would have disappeared with the influence of dominant genes or other factors.
Colors and Patterns
For show purposes, colors are grouped by division and include solids, silvers, shadeds and smokes, colorpoints, tabbies, particolors, and bi-colors. Solids are sometimes referred to as self colors. Tabbies have a pattern of stripes, patches, and bars. Silvers, shadeds, smokes have darker-tipped hairs lying against a paler ground color or undercoat color, which gives the coat a contrasting, shimmering effect, especially when the cat moves and the fur parts. Particolor is a broad term for a coat of two or more colors, such as a tortoiseshell, which is black with patches of red. A bi-color has a coat of two colors, one of which is white.
While many purebreds are bred specifically for their coloring, all of the beautiful colors, patterns, and markings that can be maintained by selective breeding can also appear randomly in the mixed genetic bag that makes up our treasured stock of nonpedigreed, domestic cats. And even though our modern-day domestic cats come in varying coat lengths, colors, and color patterns, they all are genetically tabbies, like their wild African ancestors. The term “tabby” commonly refers to the familiar striped color pattern, not to a specific breed. The pattern occurs in purebred and random-bred cats.
Bars and stripes: Most people recognize the tabby as a cat that has pronounced stripes and bars on its coat, tail, and legs, and frown marks that form an intricate “M” on the forehead.
• The classic or blotched tabby has wide stripes, swirls, patches or blotches, often forming a recognizable bull’s-eye pattern on the sides.
• The more common mackerel tabby has thinner stripes running from the backbone down the sides resembling fish ribs, hence the name.
• The rare spotted tabby, as the name implies, sports spots instead of stripes. The stripes are actually there, but they are broken in places so that they resemble spots.
The agouti pattern: There also are tabbies with no stripes at all. The Abyssinian and Somali breeds represent a unique form of tabby without stripes called the agouti pattern. These two closely related breeds—one a shorthaired type, the other a longhair—are noted for their reddish brown hair ticked with bands of darker color. The ticking, or agouti pattern, results from alternating light- and dark-colored bands on each hair shaft, giving the coat a delicately flecked appearance. The pattern occurs in some other species as well, as in squirrels, and serves as excellent camouflage.
Tabby colors: Of the tabby varieties, the most common colors are the red tabby (sometimes called orange, yellow, or ginger), which bears deep, rich red markings against a lighter red or yellow ground color; the silver or gray tabby, which sports black stripes against a silver or gray background; and the brown tabby, which has black markings on a reddish brown background.
But if all cats are genetically tabbies, how did we end up with the plethora of colors and patterns we see in domestic cats today? Well, over time, genetic changes have occurred that, depending on how genes are arranged in a particular individual, may result in masking or suppressing the distinctive tabby markings; yet, some variation of the tabby gene remains present in all cats. If a cat inherits genes that completely mask the stripes and bars, he will be a self or solid color, such as solid black, for example. But underneath, the cat is still a tabby.
Dilute colors: Generally speaking, dominant genes tend to produce darker, denser colors,
