Color Genetics of Guinea Fowl
D. Phillip Sponenberg, DVM, PhD
Guineas come in an interesting and increasingly varied array of colors. These are due to different combinations of genes, and breeders can manipulate these to get the colors they want. A few basic prinicples will help.
Genes occur in pairs, and interact in various ways. Each bird gets one of each pair from the sire, the other from the dam. In its turn, each bird provides only one of each pair to its own offspring. This is an important concept, and the gene pairs need to be understood as separating and remaking pairs at each generation.
When the genes of a pair are different, they interact in various ways. The most common is for a specific one of the pair to be expressed, and the other hidden from view. The one that is expressed in this situation is called "dominant" and the hidden one "recessive." The key concept here is that dominant genes are expressed when present as either one or both of the gene pair. Recessive genes are expressed only when both pairs are of the recessive sort. The result of this is that dominant genes can hide recessive genes, and recessive genes can therefore pop out as surprises when two birds carrying them are mated together.
The concept of dominant and recessive can greatly help to understand how to combine different genes to make different colors. One very helpful approach is to document which colors come out of the matings of other colors. For example, keets coming from pearl x pearl matings are generally pearl – with occasional other surprises due to recessive genes. By going through what pops out as surprises from each color, it is possible to discover what the genetic control is, and which are recessive.
The major variants are few in number, although some few colors remain unexplained. Most of the variants can be thought of as "switches" between two choices.
dots – few dots
This first switch is due to a recessive gene that takes away most of the dots. Adult birds have a few dots remaining on the lower aspects of the bird. Keets have striping that is more irregular than in the dotted ones, and also have a white breast. The white breast can help to detect this gene in the various combinations. This gene also darkens the color somewhat. In chart form it is possible to "build" various colors by considering the switches.
grey – blue
The normal guinea background color is grey to purple, but a single recessive gene changes this to a light blue color. By changing grey to blue, and by considering that some are dotted and some are not, it is possible to now come up with four major colors from the two genes.
The table reveals that pearl guineas are expressing neither recessive gene, royal purples are expressing only the few dots gene, lavenders only the blue gene (they are therefore blue with dots), and coral blues are expressing both so they are blue with few dots.
grey – buff
This switch changes the grey of the usual pearl guinea to a lighter brown color that is usually called buff. Hens are darker than cocks. This is reputed to be a recessive gene, although similar genes in most other birds are sex-linked as well.
The table is now getting larger and more complicated. It is possible for individual birds to have any combination of the genetic effects, which is multiplying the numbers of color classes. To simplify the tables, only the presence (+) of the expression of the gene is noted – not the absence (-).
dots – no dots
Some guineas have absolutely no dots, and the keets are red instead of striped. This is probably a separate gene, but whether it is dominant or recessive is uncertain. The effects of this with various combinations are somewhat uncertain. It is likely to be recessive.
nonpied - pied.
This genetic effect adds white patches to the bird. Birds with one dose of the gene are pied, and birds with two doses are white. The fun aspect of this is that the pied birds can be any color with white – not just pearl and white.
nonpied – irregularly pied
In at least some countries a separate sort of white spotting is noted in some guineas. This in unlike the usual pied birds in that the spotting follows no specific pattern. It is probably recessive.
"shade of color"
As a final confusing detail, the final shade of color within a color class is variable. So, the lightest pearl guinea is different from the darkest one. In some colors the variation is more pronounced than in others, and so the various shades have been separated out as different colors. The exact genetic control of these fine "shades of difference" has not be determined.
Some colors are the result of specific single changes in the genetic makeup. Others are more complicated and involved multiple changes piled on top of one another. As time goes on it is going to be possible to tease out some of the details by making test crosses. The best test cross for figuring out what major genes are present in some new, unusual colors is to mate them to an opaline bird. The results should quickly tell if "few dots," "blue," or "buff" are present, which is a great point of departure for finding out if new colors are similar to some older, established ones.
The final table is only an educated guess as to what is going on. Question marks accompany especially confusing colors.