Newer genes

Here you will find description of those newer genes, which were more described.

Recessive Dappled (rdrd) 1996 Estonia

Recessive Dappled gene was studied by Jan (The River Road Hamstery) in the USA, text bellow is used with her permission.

Description

History

Although methodical crosses to prove the nature of the pattern's genetics were not done at the time, Spice Teddybear and other area breeders came to believe that a new recessive pattern gene was responsible. They called it "Wide Banded."

Genetics

The River Road Hamstery acquired from these lines an unpatterned Golden male with a "Wide Banded" dam. Breeding was planned in conjunction with Spice Teddybear Hamstery to delineate the transmission of the pattern. Complete proofs can be found at Experimental Proofs of Gene Character and Transmission. Beyond a doubt, this pattern is indeed generated by a single-locus completely recessive gene. It was proven that this gene is not an allele of the Dominant Spot locus, and the two pattern loci probably are not resident on the same chromosome, that is, they are not linked.

As the work proceeded and the pattern was examined in many hamsters, there was reconsideration of its name. Spice Teddybear decided that "Recessive Dappled" incorporated both the mode of transmission (in an important contrast to the other common pattern genes) and the quality of the coloration on the rear of the animal. It was given the symbol rd, with Rd designating the wild type.

Breeding

Breeding for Recessive Dappled follows the same genetic rules as for any other recessive gene. Since two copies are required for the pattern to be evident, one must come from each parent, meaning that both parents must be either Recessive Dappled or carriers. A Recessive Dappled hamster should be bred to another Recessive Dappled or to an unpatterned hamster. Mixing the pattern with Banded, Dominant Spot or Roan/White Bellied is bound to generate confusion and obscure the true pattern. 

Color and coat type are pertinent, as well. With so much white, only strong, dark colors provide enough contrast to be attractive. The original lines were mostly Golden and Umbrous Golden with an occasional Cinnamon. Other colors have since been introduced. Recessive Dappled Cream and Recessive Dappled Extreme Dilute have inadvertently occurred and are regarded as undesirable. The original lines were exclusively longhaired, and this continues to be the case. It is thought that the pattern would show more clearly on a shorthaired hamster, but this would be a personal preference. 

Experimental Proofs of Gene Character and Transmission for the Recessive Dappled Pattern in Syrian Hamsters

When the "Wide Banded" pattern came to the attention of the River Road Hamstery, it was clear that the evidence for it being a recessive single-gene pattern was supportive but not conclusive. Spice Teddybear Hamstery collected data on all the relevant crosses done with the hamters up until that point, and both hamsteries planned breeding to delineate the gene. The definitive cross had to be between two unpatterned hamsters both of which were presumed carriers, producing patterned pups in the litter. This would prove that the gene was recessive.

From Spice Teddybear Hamstery

As of August 2000, there had been ten matings between an Estonian-patterned hamster and a hamster with one Estonian-patterned parent. These resulted in litters that were roughly 50% solid and 50% patterned. This would be expected whether the gene was dominant or recessive, so offered no useful information.

Three crosses between two of the patterned hamsters produced 100% patterned litters. Three crosses between a patterned hamster and a definitely unrelated solid from U.S. stock yielded 100% solid litters. These results suggested but did not prove that the gene was recessive and, therefore, completely different from the known pattern genes. (The only other recessive pattern gene known to have existed outside of labs is Piebald which may now be extinct, and unlike the pattern here, it produced color on the ventral surface.)

There was only one mating between solid hamsters both of which had one patterned parent. If the pattern gene were recessive, then each of these would be a carrier. This single cross produced a litter of four, one of which was patterned, proving the recessive nature.

To replicate these results and increase their credibility, another cross was made in July 2000 between an unpatterned Golden female that came from a patterned parent and an unpatterned Golden male that had a patterned grandparent on each side but unpatterned parents. (His chances of being a carrier were only 2/3.) Pictured here is the dam whose mother was a Golden Dominant Spot and father was an Estonian-patterned Golden.

The full litter of 12 consisted of 7 unpatterned and 5 patterned. The patterned animals are similarly marked. The darker animals are Umbrous Golden. It was not known that the parents carried Cinnamon, although both have Cinnamon in their pedigrees. The five patterned pups from above are shown below. Both sire and dam are unpatterned Goldens.

There were two other crosses of note from the Delaware breeders. One was a Recessive Dappled crossed to a Dominant Spot. The litter was a mix of Dominant Spots and solids. The other was between a Recessive Dappled and a standard Banded. The litter was solid and Banded. The patterning on the pups in these litters was typical for the pattern indicated and not intermediate in form.

(The photos in the preceeding section are courtesy of Spice Teddybear Hamstery.)

From the River Road Hamstery 

This Shorthaired Golden male has normal agouti markings. His sire was an unpatterned Golden, but his dam was a Recessive Dappled Golden, making him a carrier. He is also known to carry Black Eyed Cream and Longhair. He was mated to an entirely unrelated female, and two unpatterned daughters were saved for backcrossing. These daughters would have only a 50% chance each of inheriting the rd gene and being carriers themselves.

The two females, a Black Eyed Cream and a Golden, both longhairs, have markings typical for their colors and no indication of pattern gene effects.

The Black Eyed Cream had a litter of fourteen, including seven unpatterned Goldens and five unpatterned Black Eyed Creams. There were two Recessive Dappleds (one of each color), but the Golden died at eight days. This picture was taken at seven days when the markings are clear on the single Golden. Markings on the Cream could not be distinguished this early. 

The Golden had a litter of thirteen, including seven unpatterned Goldens and five unpatterned Black Eyed Creams. In this litter, there was a single Recessive Dappled, Golden. This picture was taken on day nine.

The contrast on the Black Eyed Cream Recessive Dappled, also at 24 days, makes the pattern more difficult to see, especially on the hindquarters where it is very light. This pup is a female shorthair.

Conclusions and Comments

The structured breeding efforts from both hamsteries prove that the pattern is caused by a recessive gene. This has since been supported by numerous other litters. It has never split into two patterns, as would be the case with a Dominant Spot Banded. The pattern itself has seemed to change somewhat over the generations with color creeping anteriorly up the back, but this remains a variable feature.

The expected percentage of Recessive Dappled hamsters born to parents who are both carriers of the gene is 25%. In litters of this size then, one would expect to see about 3 or 4 in each litter. That there were only half that many could easily be a chance phenomenon or it could be an indication of reduced viability associated with the pattern. The latter has not been indicated by the numbers of Recessive Dappled hamsters in other litters.

Recessive Dappled Compared to Other Syrian White Patterns

Recessive Dappled can be easily differentiated from other white patterns except for one — the combination pattern, Dominant Spot Banded, which has recently become standardized by the British Hamster Association. This one will be examined in detail with notes about the other patterns following. 

Recessive Dappled v. Dominant Spot Banded

The BHA Exhibition Standard (reproduced by permission) reads as follows:

The dominant spotted banded shall have a coloured head and nape of neck with a central blaze of white running from the nose to between the ears. This area shall be evenly spotted with white. Spots of colour shall be distributed along the dorsal line from the neck to the rump, with the area from the rump to the tail evenly spotted with colour and white. The white band shall cover two thirds of the body length. The spots shall be sharply defined. The belly fur shall be white. The white areas shall be white to the roots. The coloured area shall conform to the recognised corresponding full coloured variety. Eye colour: As for the full coloured variety. Ruby/red eye or eyes permissable.

Recessive Dappled shares with Dominant Spot the white belly, white facial blaze and spotted patterning. 

Although there is no standard for Recessive Dappleds, features are consistent enough to contrast it with DS Banded.

1. As noted by Lorraine Hill of the Pet Web Site, the blaze on an RD starts from the top of the head rather than from the nose, as is usual on a DS.

2. The anterior color on the RD stops just to include the ears and never covers the nape.

3. The head color on an RD is always symmetric, not necessarily true on a DS.

4. The white area over the back of an RD has no spotting.

5. The posterior spotting of color on an RD is more dithered than spotted. Since this can also be true of poorly marked DSs, it is not a defining characteristic.

6. Genetic transmission is opposite, as implied by the names. In addition, there is no lethality associated with Recessive Dappled as there is with Dominant Spot in the homozygous state.

Recessive Dappled v. Dominant Spot

Unlike Dominant Spot Banded, this pattern has no area that is consistently devoid of color. In other aspects, it contrasts with Recessive Dappled as above.

Recessive Dappled v. Banded

White Banded hamsters ideally have a clear belt of white occupying the middle third of the body. Common faults range from a little spotting on the dorsal line to an almost absent band seen only as triangles of white extending up the sides from the white belly. The clear white "wide band" on a Recessive Dappled is always over the shoulders and in some individuals extends nearly to the tail. The margins of the band on a Banded should be straight, but even when they are jagged the white does not seriously extend fore or aft to simulate a spotted pattern. There is no facial blaze.

Recessive Dappled v. Roan

Roaning consists of an admixture of white and colored hairs with the proportions varying considerably. The pattern occurs in Self hamsters except for Black, i.e., in cream-based colors. It is the effect of the dominant gene, Anophthalmic White, which in homozygotes is expressed as Eyeless White. Color is usually more concentrated on the head, but even when it fades to a predominantly white body, the white is never in organized spots.

Recessive Dappled v. White Bellied

Also caused by the Anophthalmic White gene, the White Bellied phenotype is seen in hamsters that are either Agouti or Black. In Agoutis, the belly is snow white as with the other patterns. In addition, there may be a grizzled effect owing to a slight scattering of white hairs, especially on the muzzle. On Black hamsters, the white is evident in an enlarged belly patch not covering the entire ventral surface and often mistaken for commonly seen white faults on Self hamsters. White markings are not seen on the upper parts of the animal.

Recessive Dappled v. Piebald

Piebald is the only other known Syrian hamster pattern caused by a recessive gene (symbolized s). No Piebald hamster has been seen in many years and the gene is presumed to be extinct. Old descriptions and photos in scientific papers indicate that the color was equally distributed over the back and belly, making it the only pattern gene to have ventral coloration. (Occasional color spot faults on the bellies of other patterned hamsters do not approach this equal distribution.) In contrast to Dominant Spots, the Piebald's spots were larger and less defined. This diminished definition may have been similar to the dappling on the rear of Recessive Dappled hamsters.

Testing for Allelism Between Recessive Dappled and Dominant Spot

It is established that Recessive Dappled is a new recessively transmitted pattern. Since it shares so many phenotypic features with Dominant Spot, we wondered if the two genes could be allelic. This would mean that the RD gene is a variant of the DS gene, occupying the same locus on the chromosome. If this were true, then a hamster could have Ds (the symbol for Dominant Spot), ds (the symbol for wild type) or rd (the symbol currently used for Recessive Dappled) on each of two chromosomes. If the genes are unrelated and each has its own locus,

Of interest is that in mice there is a variant of the dominant white spotting gene called panda-white wherein color is restricted to the head and the base of the tail.

The Test - Stage 1

The most important part of the test was selecting the hamsters to use. We needed:

• a Recessive Dappled that definitely had no Dominant Spot parent, and
• a Dominant Spot from a line with no Recessive Dappled relatives.

In addition to the patterns mentioned, both of these hamsters were Banded. This wasn't an ideal situation since care needed to be taken to differentiate RD from DS/Banded, but it was the best available choice at the time.

The resulting litter was expected to be roughly 1/2 DS with all pups carrying RD. It has been shown before that when DS is crossed with RD, the litter is DS or solid with no intermediate patterning. What we wanted was a DS pup to cross to another RD.

Shown below on the left is a Golden male saved from the litter produced by the above cross. He at first looks RD but is actually a DS Banded. The pigmentation around his head is assymetrical and does not encompass the ears (unlike RDs).

The Test - Stage 2

Results here depended on whether DS and RD are co-alleles or not. The second cross was the DS pup (carrying RD) to an unrelated RD female (above right) from a line with no other patterns..

If they are not allelic:

DsdsRdrd x dsdsrdrd 

Disregarding the Banded factor, the expected outcome is 25% each Dominant Spot, Recessive Dappled, Dominant Spot/Recessive Dappled, and wild type. It may be very hard to distinguish the DS/RD combination from RD alone so there may appear to be a preponderance of RDs.

If they are allelic:

We will need a new symbol for the rd gene identifying it as an allele of Ds. Since it is recessive, it will be designated ds rather than Ds, but will need a differentiating superscript for which we can retain the rd. The same cross is as follows:

Dsds(rd) x ds(rd)ds(rd) 

The litter will be about 1/2 Dominant Spot and 1/2 Recessive Dappled. The significant aspect is that there can be no wild type individuals here. If even one pup without either pattern appears, then DS and RD cannot be alleles of each other. However, if no wild type pups are produced, then this could be an event of chance. This cross would need to be repeated many times, each and every time generating only patterned animals, to say with some confidence that DS and RD are allelic.

Results

Their litter of 14 included one solid Golden and one Banded Golden, proving that the Recessive Dappled gene is not an allele on the Dominant Spot locus. Additionally, 2 unpatterned pups (disregarding the bandedness) out of 14 comes close enough to what would be expected that it is an indication that the genes are probably not linked. More crosses would be required to say this with certainty.

Recessive Dappled Photo Gallery

 (All photos are of hamsters from the River Road Hamstery except as otherwise noted.)

There are very few Recessive Dappled hamsters in existence in the Western hemisphere. Outside of Russia (and perhaps its near neighbors) this hamstery has been the only known repository for the gene since the Delaware hamster club (and with it Spice Teddybear Hamstery) folded. In 2003 some RDs and RD carriers were shipped to AAA Hamsters in California and Chesapeake Hamstery in Maryland to help preserve and develop the pattern. The task at hand has been to keep the pattern from extinction in this part of the world, and as a consequence, attention to type has been lacking.

The first RD bred at the River Road Hamstery, the "poster girl" for the genetics site, is shown above. Below are a pair of Satin Longhairs, female (left) and male (right), multiple generations removed from the first one.

The rest of the hamsters on the page are from Spice Teddybear Hamstery's original Recessive Dappled lines descended from the single hamster brought from Estonia. (Reproduced courtesy of Spice Teddybear Hamstery.)