|Double Banded Syrians
By Jan of The River Road Hamstery
| "The parents of my Banded hamster both had bands so my hamster must be Double Banded."
Wrong. In fact, if your Banded hamster has even one littermate that is nonbanded, the chances of your hamster being Double Banded are only 1 out of 3.
What It Is
"Double Banded" is a somewhat unfortunate term to indicate that a hamster has two Banded genes. It is a poor term because it seems to describe an animal with two bands or even one double-sized band, yet the band of a hamster with one Banded gene is for all practical purposes indistinguishable from a hamster with two. Some people think that having two genes for Banded might make for slightly better bands, but this has not been proven, and there is certainly a huge range of bad and good bands no matter what the genotype.
The gene in Syrian hamsters that produces the Banded phenotype is a dominant gene. This means that only one copy of the gene is necessary to give a band. The genetic shorthand for the Banded gene is Ba. A Banded hamster can have the genotype BaBa or Baba, and a Nonbanded hamster will always be baba. BaBa then is sometimes referred to as "double banded" and Baba as "single banded."
Why It Matters
It only matters if you breed. Without exception, ALL pups from a Double Banded hamster will be Banded. A Single Banded hamster will donate the gene for bandedness to about 1/2 of its progeny. For the 1/2 that receives the nonbanded allele, their appearance will depend on what they inherit from the other parent.
The Only Way to Know (and then not even for sure)
The only way to know if your hamster is Double Banded is to breed it. Double Banded hamsters will never produce Nonbanded pups no matter what the mate looks like. (The band on a Banded White hamster won't show against the coat, but in the skin anatomy it's still there.)
To see why a Banded hamster with both parents Banded is not necessarily Doubled Banded, look at all the possible crosses.
Nonbanded x Nonbanded: baba x baba = baba (all Nonbanded)
Nonbanded x Single Banded: baba x Baba = 50% Baba (Single Banded), 50% baba (Nonbanded)
Nonbanded x Double Banded: baba x BaBa = 100% Baba (Single Banded)
Single Banded x Single Banded: Baba x Baba = 25% BaBa (Double Banded), 50% Baba (Single Banded), 25% baba (Nonbanded)
Single Banded x Double Banded: Baba x BaBa = 50% BaBa (Double Banded), 50% Baba (Single Banded)
Double Banded x Double Banded: BaBa x BaBa = 100% BaBa (Double Banded)
The last three crosses are all between Banded hamsters. Taking them as a group, both Single and Double Banded hamsters can be produced. Without knowing the genotypes of the parents, all that can be said is that a Banded pup from banded parents has a 7/12 chance of being Double Banded (just a little more than 50-50). However, if there is even a single Nonbanded pup in the litter, you immediately know that the parents are both Single Banded, and the chance of any one Banded pup being Double Banded is only 1 out of three.
The Umbrous gene (symbolized U) works the same way as Banded. It is completely dominant so that there is no difference in appearance between a UU hamster and one that is Uu. Just as in Banded crosses, an Umbrous pup from two Umbrous parents is not necessarily "Double Umbrous," and also it is entirely possible to get a Nonumbrous pup from an Umbrous to Umbrous cross.
Although Satin (Sa) in Syrians is dominant, it is incompletely dominant, meaning that SaSa does not look exactly like Sasa. The desirable Satin coat is found with the Sasa genotype. "Double Satins" (SaSa) are overly satiny with a thin, unattractive coat. Double Satins can only be produced by crossing Satin to Satin (as with the previous two genes). They are kept by some breeders as Satin generators since, when bred to a Nonsatin, 100% of the progeny will be Satin. To avoid getting a Double Satin (which may be tough to place or sell) simply never breed Satin to Satin.
Jan of The River Road
Note: or more information on syrian genetics, please go to The River Road Syrian Genetics website.