Introduction to Genetics and Inherited Traits

One of the things I talked about in the previous chapter was sex-linked matings. I promised to show how this information can be used to check the accuracy of a bird's pedigree. This will be our primary focus here.

Many times, I have been asked to review pedigrees to see if they were genetically possible. Why? you might ask. Well primarily, to insure it was possible for the parents and or grandparents to produce the bird in question. Since you, the buyer, have paid your hard-earned money for offspring from certain stock, you're entitled to get what you were promised. Should the pedigree have obvious genetic errors then there is a high possibility that the bird is not the product of the stock listed.

Many times, while conducting these pedigree checks, I have found discrepancies that were without question, genetically incorrect. Two blue bars producing a red check or two non-grizzles producing a grizzle are examples. Such discrepancies bring the legitimacy of the pedigree into question. Either these birds were bred in an open loft and are the product of a non-monogamous coupling; or they are the result of some new mutation. The first possibility or adulterous chance mating is very common in open lofts while the odds for the second, a mutation, is more like winning the lottery. Possible yes but highly unlikely.

Since the hen is the one who lays the eggs, we tend to accept her as being legitimate while the cock may or may not be. Well this is normally the case but not always. Some cocks will attract more than one hen into their nest. The first to lay her eggs is not always the one to set them. Many older hens will accept eggs placed in their nest as being their own. Once accepted she can become very possessive and may drive the true mother away. If she had not begun the process of coming down on eggs herself, she simply goes into the brood condition and begins the incubation. Thus she becomes a foster parent.

Flyers simply cannot live in their lofts 24 hours a day so they're not aware of everything that goes on. Basically, any youngsters produced in an open loft should be suspect as to its true lineage. The only way to be sure of parentage is via breeding in separate pens. So how do we go about checking to see if the seller is telling the truth when he says that his birds were hatched in individual breeding cages? If they are truthful then there should be no discrepancies. I say this on the assumption that the breeder can classify the bird's phenotype correctly. In racing homer circles, this is one of our biggest weaknesses. Most flyers simply have no basic understanding of the different phenotypes and this can cause confusion when reading their pedigrees. Terms like chocolate, slate, self, silver and mosaic all have different meanings to different flyers. It is best to learn the proper terms for these phenotypes and avoid the confusion and or embarrassment when misunderstood. Example, the term silver when used by US flyers to describe a mealy is incorrect. The majority of the English speaking racing world including the US Show Fancy uses the term silver to describe a dilute blue bar. Now there is a world of difference between an ash-red bar (mealy) and a dilute blue bar (silver). We as racing types should learn to speak the same pigeon language as the rest of the world. Should you not be familiar with the proper terms or need to brush up on them, I suggest you start with Wendell Mitchell Levi's two books The Pigeon and the Encyclopedia of Pigeon Breeds. If you are the reader of the pedigree check with the breeder to learn his understanding of the terms he used. If you are the breeder, avoid the use of local terms and use the more excepted ones for clarity. But I digress so let me come off my soapbox and get back to the subject at hand: Checking the validity of a pedigree.

So how does all this work? There isn't enough time to go into all the details but let me hit the high spots and give you the tools you need to conduct a check on your own. The tools we will use are the rules governing dominant, co-dominant and recessive genes both when sex-linked and non sex-linked. We have already discussed many of these in our previous discussions so this shouldn't be to difficult to follow.

Let's begin with the non sex-linked genes. If you recall these are the ones found on the autosome chromosomes. The rules here are not associated with the bird's gender. In other words, they apply to cocks and hens in the exact same manner. These rules are simple to follow. They are in essence applying the principals of dominance over less dominant or recessive. With pedigree in hand, begin by looking at all the birds listed. Note they're marking patterns such as bar, checker etc.. We know that every pigeon carries two genes for pattern, having inherited one from each parent. These pattern possibilities are t-pattern, dark checker, checker, light checker, bar and barless. There is an order of dominance associated with these. It starts with the t-pattern markings (also known as t-check or velvet) as being the most dominant in the pattern series and runs down to barless being the least dominant or most recessive. The simplest way to remember this order of dominance is to say that the more pattern shown the higher it is on the pecking order. Nature when faced with the problem of two gene possibilities solves the dilemma by always selecting the most dominant as the phenotype.

Let's put that last statement to the test. A bird is listed as being a light checker. For this to occur, one of its parents must be at least a light checker or darker in pattern. Example: a dark check cock with one gene for dark check and one for light check mated to a dark check hen carrying one gene for bar. Thus you have two dark checker pigeons producing a light check. Is this possible? Yes, all that is necessary would be for the sire to pass along his light check gene while the dam passed along her gene for bar. The outcome would be a light checker-carrying bar. Remember the order of precedence. The more pattern shown the higher on the pecking order. The light check would be displayed while the bar would not. During future reproduction, the gene for either light check or bar will be selected at a rate of 50/50. Should this light checker/bar be mated to a bar/bar partner then 50% of the young will be light checker/bar and the remainder bar/bar. The light checker/bar will appear as a light check in phenotype where as the bar/bar will be a bar in phenotype. Color does not enter into this equation even though color can also be used in sex-linked identification. We will get into that in just a few minutes. From the pedigree, we can't tell what the unseen pattern gene is. We only know the one, which is shown or listed on the paper, so we must follow the first rule of what I call "The Ten Commandments of every Pedigree".