Cat College: Feline Genetics
Session 100: Feline Genetics
The study of heredity in cats reveals why they look, walk and react the way they do.
By Sandy Robins
Posted: December 1, 2009, 3 a.m. EST
First Semester Cat-lective
Genetics is the study of heredity. From the feline standpoint, it’s a scientific way of tracing your cat’s family tree and learning how your cat came to look, walk and react the way it does.
Every cell in a cat’s body contains a nucleus that carries 38 chromosomes arranged in 19 pairs. Cats inherit half their chromosomes — or 19 — from each parent.
Each chromosome is formed from what is called a double helix of deoxyribonucleic acid (DNA), which in turn is made up of thousands of genes. The information stored in the genes determines whether a cat is born male or female, its eye color, fur color and length, and the other characteristics of its physical appearance and personality.
However, feline genetics not only looks at these physical characteristics and inherent character traits, but also at inherited internal physiology. If geneticists can pinpoint the genes that carry conditions, such as kidney disease, and discover why white cats are predisposed to deafness, they can work to eradicate these genes and prevent these issues from occurring in future generations of felines.
Dominant and Recessive Genes
A dominant gene is one that produces a physical manifestation of internally coded, inheritable information with only one copy of that gene present. A recessive gene, however, requires two copies of the gene to be present for the trait to be physically expressed.
In the course of normal reproduction, genes occasionally mutate and it’s these mutations, or changes, in genetic material that bring about variations in color, coat type and body shape in cats.
Consequently, breeds have emerged over the years that are characterized by distinctive mutations, such as the folded ears on the Scottish Fold and American Curl, or the bobbed tail of the Japanese Bobtail, American Bobtail, Pixiebob and Manx.
Today, breeders work very closely with geneticists because, by studying the genetic makeup of different breeds, they know what kind of results they can produce by pairing up different cats.
Four Main Breeding Methods
Linebreeding involves breeding cats who are of the same bloodline but are not closely related. For example, a cat would be mated with a grandparent or cousin. This method is most often used to produce good examples of a particular breed.
Linecrossing involves mating two good examples of a breed that are in no way related to one another in the hope of combining the good qualities of both cats.
Crossbreeding involves mating cats of different breeds. This brings genetic diversity to established breeds and also results in new breeds often referred to as “hybrid” breeds, such as the Savannah.
Inbreeding involves mating closely related cats. However this can cause medical problems and deformities; to avoid this, responsible breeders need to work with a very wide gene pool.
Most domestic cats have coats that are a variation of striped or blotched fur patterns reminiscent of their wild-cat ancestors that lived approximately 10, 000 years ago in the area in the Middle East known as the Fertile Crescent.
This coat pattern is called agouti — more commonly known as a tabby pattern.
Because so many cats have this pattern in their fur, the word “tabby” has become slang to describe a cat breed instead of what it really is — a coat pattern. Similarly, cat lovers often refer to their cat as a calico or a tortoiseshell. Once again, these are not cat breeds but coat color and pattern descriptions.
Calico cats have a significant amount of white fur, plus two other colors broken up into distinct patches. In a tortoiseshell cat, the three colors are blended and don't form distinct patches.
Cat fanciers have some interesting descriptions for cat fur colors and distinctive markings on the face, ears, feet and tail areas.
Breeders use the term red for the color that is commonly referred to as orange, marmalade or ginger.
Similarly, they will describe shades of gray as blue. All shades of gray are diluted forms of a gene that produces a black-colored coat. The color is further diluted to produce colors known as lilac and lavender, which are the lighter shades on the gray scale.
A coat that is all one color all over is called solid; a coat that is one color but has white roots is called smoke.
When cats have a lighter shading on the face, paws and tail, it’s known in the cat world as points.
With this overview of descriptive words used to illustrate genetic traits, you’re ready to enjoy and understand the lingo used at cat shows.
Sandy Robins is an award-winning pet-lifestyle expert who appears regularly on TV, radio and in international publications. She is an obsessed pet owner to her cat Fudge.
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Cat College: Feline Genetics