Mosaicism in Seraphim

Mosaicism is the status of having more than one genetic population of cells in a single individual which developed from a single fertilized egg. This condition can be caused by a spontaneous mutation in a single cell in the early embryo that leads to the mutation being multiplied every time there is another cell division as the embryo develops. It can also be caused by less than robust DNA replication during cell division (mitosis) so that some genes become inactive or are left behind. Mosaicism occurs easily due to the millions of cell divisions and possibilities for replication errors that occur during the development of an embryo. In fact, 70-90% of complex organisms (maybe all?) are affected by mosaicism.

Mosaicism can involve any type of chromosome and its genetic apparatus. Some genetic changes are visible, and others are invisible. An example of visible mosaicism could be something as simple as a large birthmark where a single genetic change results in a population of skin cells that looks different from all of the rest. An invisible mosaic might have two or more lines of cells with genetic changes that result in slight variations in the molecular structure of the enzymes produced by the different cell lines. In most cases mosaicism does not lead to disabilities, but it sometimes can.

Last year I hand-raised a little runt of a baby Seraph that grew into a beautiful adult. As a juvenile it had the usual red Satinette markings, in this case lacewing/spot-tail. I didn’t study each feather, but it turns out that one of the tail feathers was not recessive red. When the bird molted into adult pure white feathers, she had a single perfectly marked tail feather in blue with a perfect white spot. Why did this happen? Sometimes mosaicism can happen in a very tiny patch of tissue – in this case in a single feather follicle. The cells in that follicle lost their functioning Seraph Color Gene Complex for some reason during embryonic development.

A year later I paired the Mosaic hen with the single spotted tail feather with a perfectly marked (pure white) Seraph cock. Their third baby was a wonderful specimen but had a large patch of brown mosaicism on his right wing-shield. Here he is below, still a baby, but showing a brown lacewing pattern in the shield of his right wing where the white-sides and recessive red genes failed to express. He has an entire segment of a wing that is missing the genetic machinery of the Seraph Color Gene Complex. I didn’t notice this when he was a baby as the drab markings didn’t register as being different from the surrounding recessive red feathers he had at the time. Now it is obvious. the bird to his lower right is the same age and has nearly complete replacement of red feathers in the wing shield with white as expected. The juvenile red tail feathers in both birds have yet to be replaced – that is NOT mosaicism.

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The father of this bird has sired at least thirty offspring with another perfect white Seraph hen, none of which demonstrated color mosaicism, so the trait seems to have been passed down from the hen. Since this Mosaic appeared, two more have appeared in the same nest, each with a colored tail feather in the exact same position as their mother’s-colored tail feather. The hen and three Mosaic babies were taken out of the breeding pool. Seraphim are a product of careful inbreeding and have complex recessive traits. One can see how careful you must be to avoid genetic pitfalls that can ruin the color of an entire line of birds.

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The only other Seraph mosaic I ever had was in 2009. I didn’t understand what he was. He was a beautiful and stunning bird. I sent him to California to a fellow near Sacramento. A year later he called me to tell me that the colored feathers contaminating the birds left wing did not disappear at the second-year molt. It was only then that I realized the colored feathers were brown, not recessive red, and would never disappear. At the time I advised him to breed the bird, as it was otherwise amazing and the standard opinion at the time was that mosaicism wasn’t necessarily inherited, but rather just a genetic accident. Well, that was wrong. A genetic accident – yes; a non-inheritable genetic accident – no.

The moral to this story? Watch very carefully for evidence of genetic abnormalities in your Seraphim and remove anomalous birds from the breeding program, whatever the fault. If a mosaic appears in your loft, it may just be a spontaneous mutation, but if a second one appears from the same parents you must conclude that there is a genetic issue with one of the parents and proceed accordingly.

David Coster

Seraphim: Does Color Matter?

Seraphim are a white color created by a special set of color genes called “The Seraphim Color Gene Complex.”

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The 2017 Seraphim Standard of Perfection as depicted in the new NPA Book of Standards. Seraphim are pure white as adults.

Based upon the history of how the breed was developed as well as test crosses, the color genes known to be present in Seraphim are: Recessive Red (or yellow), Satinette Piebald, White Flight, White-Sides, and some unknown genetic factor(s) connected to the White-Sides gene that also turn the tail white – “tail-whitening” genes. This gene combo is “The Seraphim Color Gene Complex.” As for visual color, Seraphim MUST at first be recessive red or yellow as juveniles, and the color distribution MUST be specifically in the Satinette pattern, i.e., colored wing shields and tail. The head, neck and body are piebald (white), along with the 10 primary flight feathers. The Satinette pattern does not have to be perfect in young birds (it is difficult to breed a perfectly marked Satinette), but the pattern must be apparent. With the first molt, red or yellow feathers are replaced completely with white (on occasion this may take two molts to get every red feather). Typically, a Seraph is pure white by 6 months of age.

Being in the Owl family and originating from the Classic Oriental Frill, Seraphim also have lots of structural mutations unrelated to color that vary from wild-type, including – but not limited to – grouse foot feathering, chest frill, needle-point peak, mane, gullet, and short beak. Other genes influence stance, feather length, and skull shape and size, which are all critical factors that differentiate Seraphim from other breeds. These traits are inherited with the influence of multiple genes and modifying factors and are significantly affected by careful (or careless) breeding programs. Seraphim look substantially different in form than their breed of origin due to highly selective breeding. The breeding program has significantly modified how the structural genes in Seraphim are expressed. Seraphim are today significantly modified from their original breed of origin.

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The above old archival photo shows an early Seraph cock with his juvenile offspring. A couple of things stand out. First, this cock from the early years is noticeably shorter and stockier than the current standard and is not considered ideal by today’s Standard. Second, note the recessive red coloration in the baby, as well as the mismarked primary flights and neck feathers. Notice that the tail feather and wing covert feather tips are emblazoned with red. This six-week-old baby is mismarked and overmarked, but you get the idea; you can see that the underlying visual color pattern is Satinette Piebald. The discontinuation of pigment production occurs after juvenile feather formation. The juvenile markings may demonstrate the underlying presence of oriental frill stencil and/or toy stencil.

First baby out of NoBand and Snow. 2012. One month old.

The above 2012 photo of a rather petrified little Seraph demonstrates the Satinette pattern of the juvenile: red wing shield and tail, white everyplace else. Note that the pigment distribution is different in this baby, and muted compared to the other (may be dilute, i.e. yellow.) The red may be spread and pure, or it may be faint with just the tips of the feathers affected, or some pattern in-between as in this case, but it MUST be in this Satinette distribution. The Satinette markings are perfect in this baby – there are no mismarks in the white feathers of the body, neck, and head – but perfection is not required (only desired) in the juvenile phenotype (appearance), as long as the proper genotype (the necessary genes for the basic Satinette pattern) is present. You can see this baby is a “lace-wing, lace-tail” specimen now, but you won’t be able to tell that in five months when it turns white. With known Seraphim parents, the presence of the Satinette pattern in recessive red or yellow confirms the color pedigree of the young Seraph.

When the first molt is complete at 5-6 months of age, the young Seraph should be pure white – as demonstrated in the photo below of the baby from the previous photo taken at the Des Moines ISPA Show. The transformation to white in Seraphim due to the Seraphim Color Gene Complex is what is different about the white of Seraphim. There is typically no transition period; no gradual or progressive change to white over successive molts – it is immediate with the first molt. Sometimes a few red feathers will remain after the first molt simply because they weren’t replaced. Such residual red juvenile feathers will be replaced with white at the second molt or intermittently before the second molt.

A particularly beautiful young Seraph cock.

A gorgeous young Seraph cock. This is the baby seen in the photo above it, now a young adult shown at the Des Moines ISPA Show. It is an absolutely dazzling pure white after the first molt as expected. Not a red feather remains. Also notice how different in form this modern-day Seraph is from the much earlier Seraph cock in the first photograph of this article. This bird demonstrates the long line and regal statuesque structure expected of today’s Seraphim.  The feather ornaments are important. The frill is expected to be huge, as in this bird, and the peak must be a fine point, the mane must make a perfect line in the back, the swoop must be deep, and the toes must be finely feathered to the ends.

So, color and pattern matter, as does form. The Seraphim Color Gene Complex must be visually demonstrated in juvenile Seraphim, along with the expected structural attributes demanded by today’s Show Standard as the birds mature. This confirms the presence of a proper genetic pedigree in the juvenile bird as well as the adults that produced it. Introducing the Seraphim Color Gene Complex into a population of Classic Oriental Frills does NOT create Seraphim. The fine-tuned physical attributes that make a Seraph a Seraph are lost in the process, as is the personality, and the result is neither quality Classic Oriental Frills nor quality Seraphim – all the work of selective breeding is lost. The only way to assure Show Quality Seraphim is through the purchase of high-quality stock with a known pedigree, followed by a dedicated and scrupulous breeding program to maintain the genetic modifiers that affect structure.

For some, Seraphim are the most visually exquisite breed of Fancy Show Pigeon ever created. The decades long process to create their delicate, angelic, and regal appearance while yet maintaining a strong natural constitution was an arduous combined artistic/scientific endeavor requiring the input and help of many experts, including Doc Hollander. As the developer of the breed, Anya Ellis is in real-life an artist. Seraphim are, at the end of the day, not just a complicated genetic enigma. They are really living art designed to be a gorgeous addition to any loft.

David Coster

Editor, The Seraphim Club International

The Magic of Seraphim Genetics – A Deeper Dive for the Serious Breeder

So, let’s take a deeper look at what makes Seraphim so special genetically, this “thing” that causes them to transform from a red Satinette color pattern to a pigment free, pure dazzling white – and how does this differ from the white of other pigeons in pattern of inheritance? And what else is going on genetically in Seraphim that makes these Fancy Pigeons different than their breed of origin, the Classic Oriental Frill? If you are unfamiliar with basic pigeon color genetics you can skip down in this same article to the section called Basic Pigeon Color Genetics and review it before diving into the explanation that begins immediately below:

Let’s start with some basic definitions and descriptions of what we know at this point – based upon the known history of the breed and breeding experiments – of the crucial genetic components that make Seraphim distinct from other breeds. As for color, the “Seraphim Color Gene Complex” – the combination of genes that cause Recessive Red to appear and disappear – is the key.

SATINETTE PIEBALD:  The first genetic requirement is the Satinette Piebald pattern of color distribution, a pattern that also includes the Dominant White Flight gene. The three additional genes of the Seraphim Color Gene Complex are overlaid on the Satinette Piebald color pattern. These are unimproved “Recessive Red” (a dull brownish red compared to improved red which has other genetic color influencers and is a deeper red and more lustrous) combined with the “White-Sides gene” and an as yet undefined “Tail-Whitening” gene(s). (The so-called White-Sides and Tail Whitening “genes” may not be genes at all, however. Rather, they may be genetic “switches” or gene controllers. As genetic switches they are inherited, but they are not “genes” per se. Genes direct the manufacture of specific proteins; switches are gene controllers, turning genes on or off, making them function or not.  In the case of Seraphim, the Recessive Red gene is initially turned to “on” to produce pigment, but then turned to “off” by the White-Sides and Tail-Whitening gene switches to create the absence of pigment in the adult.) 

The Piebald and White-Flight genes that make the “Satinette” pattern of a pure white body, head, neck and primary flights with colored wing shields and tail has long been established in Oriental Frills. Along with the additional Recessive Red gene and the White-Sides and Tail Whitening “controllers” (or “switches”), they are presumed to be integral to the Seraphim Color Gene Complex. The inheritance of the Piebald genes for the body, head, and neck in Classic Oriental Frills, and their patterns of visible expression are poorly understood and may also be a consequence of switches as well as actual genes. Most piebald patterns are difficult to maintain without highly selective breeding and very careful attention to color patterns when pairing birds. Piebald does not necessarily express the same every time.  Interestingly, in Seraphim, juveniles which have mismarked red pigmented feathers in areas that are supposed to be white based on the Satinette Piebald color pattern still molt completely to white, suggesting that the “controllers” that stop pigment production in the wing-shields and tail are also having a broader effect on the whole body, head, and neck. 

RECESSIVE RED MUTATION: The Recessive Red mutation is a recessive gene on one of the regular (autosomal) chromosomes which, when transmitted from each parent, overrides or masks the primary Ash Red, Blue, and Brown sex-linked color genes that normally determine the basic color of all pigeons. It usually masks feather pigment patterns as well, with exceptions. Birds with a pair of these recessive genes will appear “red,” while birds with only one of these genes will show the color carried by their sex chromosomes – Ash Red, Blue, or Brown. Recessive Red is epigenetic to all other colors except Recessive White and albino, i.e., it hides or “paints over” (dominates) them so they are not seen. However, Recessive Red does not “paint over” white piebald areas or stencil patterns. Recessive Red Satinette Piebald birds will thus appear red in the wing shields and tail regardless of the underlying sex-linked color of the bird, and they will show a spread, barred, or lacewing pattern and a lace tail or spot-tail pattern. The “Dilute” gene will modify the red color to yellow if present. Since all Seraphim are Satinette Piebald as a base color pattern as well as homozygous for Recessive Red or Yellow, they appear at first feather to be marked as Red (or Yellow) Satinettes. Seraphim babies are never white.

THE WHITE-SIDES GENE: The “White-Sides Gene” is expressed ONLY in birds homozygous for Recessive Red or Recessive Yellow (Dilute), and it is probably not a gene, but rather a gene controller or switch that is linked to the Recessive Red gene.  Pigeons of any color may carry the White-Sides trait invisibly. If a Recessive Red or Yellow pigeon carries one copy of the White-Sides gene, the wing-shield will turn partially white or “rose” with the first adult molt; if it carries two copies the wing shield will turn completely white. Seraphim are homozygous for “White-Sides” and Recessive Red – they carry two copies of each trait, so the effect of the combined genes is fully expressed at the first molt – their red shields are replaced with white. (Again, I’m fairly convinced that “White-Sides” is not a gene; it is more likely a switch that turns the Recessive Red pigment production gene on and then off, or a mutated master controller DNA sequence that directs a switch to turn the Recessive Red pigment production gene off. The biology of how genes actually work and are controlled is interesting and complicated. More is learned every day. It’s not as simple as we once thought.)

THE TAIL-WHITENING GENE: The “Tail-Whitening” gene(s) is presumed to be a separate autosomal gene (or genes) that causes the tail to stop producing pigment and turn white. The mechanism is not understood. (Probably not understood because, until only recently, no one understood the concept of “master controllers” and “switches” in regard to genes.) Again, I suspect the Tail Whitening Gene” is really just a mutation in the master controller that causes it to signal the genetic switch to flip to “off” at a certain point in feather pigment production. In experimental crosses of Seraphim with pure Recessive Red pigeons, crosses of the F1 and F2 generations result in birds with a mix of rose, red, and White-Sides in the shield with red or white tails, proving that the White-Sides and Tail-Whitening traits can be split out from each other. In Seraphim the whitening effects of the various genes and gene controllers act as though they are switched on together but based on the breeding tests it is clear that the gene controllers for White-Sides and the Tail Whitening gene are different.  **Note: There is a color variety of Uzbek Tumbler called a “Tschinnie” that is native to the Ottoman area (modern day Turkey etc.) that is Recessive Red and molts to either pure white or various beautiful predictable patterns of red and white with the first molt. There is a description of Tschinnies in Axel Sell’s book “Pigeon Genetics,” pp. 130-132. In personal email conversation with Dr. Sell he acknowledges that the genetic similarities between Seraphim and Tschinnies cannot be ignored, as they both are Recessive Red with the Tail-Whitening and White-Sides trait, and the Oriental Frill and Uzbek Tumbler breeds arose in the same area of the world. 

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The Tschinnie colored Uzbek Tumbler may be the ancestral source of the recessive red and all of the whitening genes that exist in Seraphim today. For various reasons I suspect the Red Neck variety to be the most likely culprit. In test crosses performed by Andreas Leif in 2006 of the RedHead/Neck variety, the RedHead/Neck trait was found to be allelic to White-Sides; Leif also suspected that a dominant enabler (switch) was required for expression of both the Whitesides and RedHead/Neck trait. (Photo from Axel Sell, “Pigeon Genetics,” page 131.

According to Mr. Sell there is anecdotal evidence that the Tschinnie color gene combination was deliberately crossed into Old-Fashioned Oriental Frills, probably in the 1800’s. If this is true, then no matter how small the possibility, it could be predicted that Anya Ellis’s effort to make a Recessive Red Satinette Old-Fashioned Oriental Frill in the U.S. in 1986 using only existing Old-Fashioned Oriental Frills could potentially throw those Tschinnie genes back together again in her loft. The Old-Fashioned Oriental Frill had been essentially abandoned in the United States at that time and the breed was not recognized by the NPA. Everyone was breeding Modern Oriental Frills instead. Anya’s original red project caused her to seek high and low for Old-Fashioned Oriental Frills (as they were called then, Classic Oriental Frills today) and bring them to her loft because she needed to find Recessive Red genes if they existed in the population, and she needed genetic variability. She became distracted from her Recessive Red project by the Seraphim Project, however, when the two Seraphim appeared in her loft, and she spent the next 30+ years working on that instead.  Others became interested in the Old-Fashioned Oriental Frill again because of the Seraphim Project and Anya sold many of her Satinettes to other interested breeders including Harold Collett who later established the Classic Oriental Frill Club in 2003. Anya’s projects thus set the wheels in motion that both created Seraphim AND re-established the Classic Oriental Frill breed which has today become so popular. A Recessive Red Satinette, however, was not ever created by Ms. Ellis and could not be created from within the existing population of Classic Oriental Frills because a pure Recessive Red did not already exist within the population. Historically, pure Recessive Red Satinettes did not exist in the U.S. in the Old-Fashioned Oriental Frill population and a good red was impossible to maintain in Modern Oriental Frills – the color quality was poor, and they tended to fade to a near-white with successive molts. Eventually an improved Recessive Red was bred into the existing Modern Oriental Frill population, solving the “Fading Red Problem” in Moderns. However, the “Fading Red Problem” was made more confusing by the fact that Ms. Ellis gave many of her Old-Fashioned Oriental Frills to interested breeders who became the early members of the Classic Old Frill Club, and some of those birds were carriers of the Seraphim Color Gene Complex (which only includes a regular or unimproved red) so occasionally an unimproved Red Satinette Old-Fashioned Oriental Frill would appear unexpectedly in a loft – a different “Red Problem” than the original, as was both poor color intensity and inherited along with all the other Seraphim color genes. The Seraphim Color Gene Complex today has been bred out of Classic Old Frills and new members of the Classic Old Frill Club have managed to introduce a pure improved Recessive Red back into Classic Oriental Frills. Mike McLin succeeded in creating high quality Red Satinette Classic Oriental Frills by using an outcross to a high- quality improved Red Modern Oriental Frill and aggressively culling the offspring to eventually create an improved Recessive Red Classic Old Frill. (Purebred Pigeon Magazine. Mike McLin – “Making it More Interesting,” March/April 2020, pp. 56-57.) Others may have had success using out-crosses as well but simply not published about it.  Today improved Recessive Red is recognized in the Classic Old Frill in both Satinettes and Blondinettes. All of this historical information is important both for Seraphim fanciers and Classic Oriental Frill fanciers.

And now going forward, for the sake of simplicity in understanding all of this, we’re going to think about the Seraphim Color Gene Complex as a combination of genes inherited together as if they are a single entity rather than multiple genes and switches and master controllers. It makes it easier to think about breeding them if one understands that although the Seraphim Color Gene Complex is many genes (or modifiers) it will always come through as if it were a single recessive gene as long as Seraphim are bred only to each other.

So, to review: for the Seraphim Color Gene Complex the Recessive Red, White-Sides, and some unidentified Tail-Whitening genes were all inadvertently re-combined in 1986 in two offspring of Old Fashioned Satinette Oriental Frills, birds that had an established piebald color pattern which makes the whole bird white except for the wing shields and tail. This Satinette Piebald color pattern is the background color pattern in all Seraphim. The visual color pattern in juvenile Seraphim is therefore entirely white with the Recessive Red gene showing up only as red marked wing-shields and tails, as one would expect for any Satinette Piebald marked bird. The White-Sides and Tail-Whitening genes (switches) turn on in adulthood, turning off pigment production before the first molt when the bird turns white.

When the adult molt occurs at about four months ALL the adult feathers come in pure white. Once activated, the White-Sides and Tail-Whitening traits prevent the production of pigment for the rest of the bird’s life. The only time color will ever be seen in a Seraph is thus with initial feather development in the nest. As far as we know, no other white Fancy Pigeon in existence owes its absence of color pigment to this particular combination of genetic processes. Seraphim are unique in this way.

This 5-week-old Seraph demonstrates the visual effects of the Satinette Piebald genes and the Recessive Red genes. Color is primarily expressed on the wing shields and tail in Satinette pattern.  (See discussion.)

The same Seraph after his first molt, now white due to the full expression of the White-Sides and Tail-Whitening traits linked to the Recessive Red gene in Seraphim. Note that the red mis-marked feathers in the piebald white areas of the chest and head in the juvenile at left are replaced above with white as well.
OTHER REQUIRED TRAITS: The needle-point peak in the Seraph is autosomal recessive. The unusually large, ruffled frill (or cravat) is the result of two recessive genes which code for the chest frill (kr1 and kr2) that are both present in the Seraph. The feathered toes are called “grouse” and are a recessive trait. Like a kid glove, each toe is individually seen and individually feathered. The short beak (ku) is polygenic, i.e., is inherited with the involvement of more than one gene. As you can see, Seraphim carry a lot of recessive traits, all of which have to be donated by each parent and present on chromosomes in pairs in order to be seen.

The visual conversion from recessive red Satinette pattern to pure white as a result of the expression of the Seraphim Color Gene Complex –  Satinette Piebald, Recessive Red, the White-Sides gene, and the Tail-Whitening gene(s) – is an absolute defining trait for Seraphim. Any bird that does not show Recessive Red (or Yellow – the dilute of Recessive Red) in the wing-shields and tail and go through this transformation is not homozygous for the Seraphim Color Gene Complex and is not – by definition – a Seraph. Selective breeding for over thirty years has created additional enhancements of body form and feather with an overall refinement and lengthening effect, giving the Seraph an unusually beautiful long flowing line, height, posture, and overall stunning regal look that is distinctly different from the breed of origin, the Old-Fashioned (Now “Classic”) Oriental Frill. The toe feathers are longer, more refined and delicate; the skull has a more defined arc, the swoop and mane are deeper, the frill is larger, and the beak is more downturned. This is easy to see when comparing the 2017 Show Standard for Seraphim to the Show Standard of the Classic Oriental Frill. Since 1986 the differences between the two breeds have become increasingly evident as both have been modified by different goals of selective breeding. The Seraph is a breed that is now separate and stands on its own. 

BASIC PIGEON COLOR GENETICS

(Please note the links in this article to Wikipedia entries and other sources that can be helpful. This can all be very difficult even when stated as simply as possible! Yet some basic understanding of these principles is necessary for the breeder of any Fancy Pigeon. The National Pigeon Association website has in-depth articles on pigeon genetics for those who wish to immerse themselves.)

CHROMOSOMES: The pigeon has forty pairs of chromosomes (or eighty individual chromosomes). Unlike other cells in the body, the sperm and the egg each have just forty individual chromosomes, or half the total, thanks to a process called meiosis which occurs only in testes and ovaries. When fertilization occurs and the sperm penetrates the nucleus of the egg, each sperm chromosome finds it’s match in the egg nucleus and pairs up with it. The fertilized egg now has a complete complement of forty paired chromosomes, or eighty total chromosomes, a normal pigeon cell. That cell immediately begins to divide using a new process called mitosis in which all of the chromosomes are duplicated just before division so that each division results in two cells with the full complement of eighty chromosomes. A great deal is now known about how this initial cell becomes an embryo and then a fully developed chick, but the details are too complex to discuss here. Enormous textbooks are written on the subject, and every day massive dissertations as well! It is wonderfully complex and amazing.

Anyway. During meiosis the various genes on the individual chromosomes remain reasonably consistent, but variation exists in the proteins that make up the DNA in those genes. Every time a new egg or sperm is formed there is the possibility that its chromosomes carry tiny changes in the order, or sequence, of the DNA proteins in the various gene segments. It is this possibility for change that results in genetic variability, or differences that may be seen in the fully formed organism.

“Dominant” genes are segments of DNA that always express themselves over any mutation of the same gene sitting on the opposite paired chromosome. For instance, if a mother donates a gene for blue eyes and a father donates a gene for brown eyes, the child will always have brown eyes; brown always dominates any other eye color. The blue gene is there, but it is not visually expressed; it is “hidden” and will only show up if given a chance to pair up with another blue gene in the next generation. That blue gene may be passed on for several generations before finally getting the chance to appear when matched up with another person also carrying at least one blue gene. The blue gene is thus “recessed,” – or hidden – a “recessive” gene. It may also be called a recessive “trait”, or “characteristic.” Recessive genes or traits become important only when both parents carry them, as therein lies the only possibility for them to be expressed or seen.

“Partial Dominant”, or “Dominant with Variable Penetrance” are terms used to describe genes that are always expressed – but to a variable degree – when present, depending upon the effect of other genetic conditions present. Feathered legs and feet are an example of this phenomenon. The gene that causes this is dominant to the bare leg gene, but the variability in the penetrance – or visual expression – of the gene can result in anything from enormous leg “muffs” to “slipper” feathers to “grouse” feathers to “stubble” and anything in-between, depending upon other genes modifiers present that add to, or subtract from, the degree to which feather growth on the feet or legs is allowed.

There is also something called linkage. Sometimes genes are locked together and are passed on as a group that cannot be broken apart by the process of cell division and meiosis. In such instances, these linked genes are always expressed together at the same time, so for all intents and purposes the combination acts as if it is a single gene in the way it is passed on or inherited. Linkage may be partially responsible for some of the way color is passed on in Seraphim.

So, let’s review. Now you understand that each parent bird passes on half of its set of chromosomes in the egg or sperm so that the new chick has a full set of chromosomes – half of them from each parent. You also understand that some dominate genes on chromosomes overpower or dominate weaker recessive genes at the same location on the opposite paired chromosome; the paired chromosomes may carry a recessive gene each, a dominant gene each, or a combo of recessive and dominant. As Dominant always wins, the only time you can see hidden recessive traits is when they are on both chromosomes in the pair, so the trait has to come from each parent to appear. Linked gene combinations transfer multiple traits to the offspring all at once, and always together, so for all intents and purposes linked genes are inherited as if they are a single gene or trait.

SPECIAL CHROMOSOMES: So, let’s go back to those forty pairs of chromosomes once again. One of those pairs has a very special function: it determines the sex of the bird. This pair has a special name: sex chromosomes. The other thirty-nine pairs of chromosomes are called autosomal chromosomes, and they program almost everything else in pigeon development with a few exceptions

In Pigeons the sex chromosomes are called Z and W. The hen is ZW and the cock is ZZ. So, the W sex chromosome is responsible for creating the female sex. The hen thus determines the sex of the chick through the egg, as she always donates a half of her set of chromosomes to an egg. By chance, half her eggs will carry a Z and half will carry a W; the eggs with W will produce hens. The cock can only contribute one of his two Z’s, since that’s all he has. In pigeons, the genes for the primary base color of the feathers – ash red, brown, and blue – are also located on the Z sex chromosome. This knowledge can be a useful tool. Since the hen has only one Z, a breeder KNOWS that she has just one basic color gene on her Z chromosome and can pass only that one color gene to ALL of her male offspring. Her color is also true – her appearance matches her one color-gene on her Z sex chromosome; if she is blue she carries only blue, if she is ash red she carries only ash red, if she is brown she carries only brown; nothing is hidden from the eye. Her W does not carry a color gene, so her female offspring MUST have their base color determined by one of the two Z chromosomes from the cock, whichever one he contributes at fertilization. One can thus determine what colors the cock is carrying by the colors that are expressed in his female offspring. This is a general basic fact that can be helpful for all breeders.

I wish it were just that simple, but obviously there are other color-pigment and pattern altering genes present in pigeons or one wouldn’t see all of the different colors and patterns one sees at Fancy Pigeon Shows. Most of these color and pattern modifiers are located on the autosomal chromosomes and a few on the sex chromosomes. No matter what, though, every pigeon has a base color of ash-red, blue, or brown on the sex chromosomes; those colors can either be fully expressed, modified, or completely masked by color-modifying genes on the autosomal or sex chromosomes.

Now it’s time to go back to the top and read about the specifics of color in Seraphim!

I