Back to Genetics
For instance a white rat that is genetically an albino may look just like a pink eyed white rat that is not albino, but whose color has been faded out from dilutions. Although they both have the same genotype (pink eyed white) they have very different genotypes (genetic makeup).
In the wild, rats are typically agouti (with an occasional albino or non-agouti showing up as a natural mutation. Their fur and whiskers are straight, the ears are placed on the top of their heads, and they usually do not have any white markings.
Looking at the rats we have in the fancy now gives you an idea of just how many phenotypical mutations have naturally occurred in the breed . They include any types other than agouti self with standard coat and standard ears.
Often, a mutation is not as simple as dominant or recessive. There are also mutated genes that act as modifiers or in combination with other genes, and within gene mutations there are usually variations and degrees of expression.
As mutations that affect phenotype have occurred and came to the attention of breeders, there have been some who took an interest in them and chose to work with them.
When working with a possible new type, a breeder will systematically breed, and inbreed the rats in order to learn.
Determinations involving Possible New Mutations
(The questions a breeder seeks to answer)
There is a recessive mutation on the agouti locus for non-agouti, and a non-agouti rat with no color dilutions is a black rat.
There are also color dilutions that can change the appearance of an agouti or a non-agouti-based rat, and these color mutations are typically recessive. They can affect both coat and eye colors and include fawn/beige, champagne/amber, mink/cinnamon, chocolate, blue and Russian blue.
Color dilutes can be combined on an animal to make other shades.
The fur can appear sparse or or even be nearly hairless when the gene is double dosed on an animal.
There are also several hairless mutations. Hairless mutations are carried recessively.
Genetically hairless rats can actually have various amounts of fur on their bodies and still be true type hairless.Their whiskers are curly from birth (as are rex).
Sometimes hairlessness is associated with certain issues such as: inability to lactate, autoimmune disorders, predisposition to cancer and skin problems.
Satin is another coat mutation. It is a recessive gene that produces rats with longer, shiny fur as well as whiskers that are slightly bent. The satin mutation also tends to add a yellowish cast to white or light-colored fur.
Posted on October 30, 2005, 08:33,
Last updated on December 18, 2008, 14:24