Lineolated Parakeet

Last up-date May 11th, 2005

First, it is important to note that there are nine distinct species of the genus Agapornis (agape, love; ornis, bird = lovebird). All are native to mainland Africa except for Agapornis Canus (Madagascar), which is native to the island of Madagascar. Agapornis roseicollis (peach faced), Agapornis fischeri (fischer's), and Agapornis personatus (masked), are the most common species found in aviaries and pet shops. Other less common species are the Agapornis lillianae (Nyasa), Agapornis nigrigenis (Black-Cheeked), Agapornis Canus (Madagascar), Agapornis taranta (Abyssinian), Agapornis pullaria (Red-Faced), and, Agapornis swindernia (Black-Collared).

Genetics comes from the Latin word “birth”, or, “generations” and is the study of birth and the genesis of life.

In this article I will be referring mostly to the color mutations of the Agapornis roseicollis or peach faced lovebird, as they are the species most commonly found in aviaries and pet shops. Keep in mind however that the theory is the same for all species. The differences between most of the species are in the number of mutations and factors available, and mostly their forms of inheritance, which we will talk about later. I want to also make it clear that this is my personal attempt to try and explain how genetics work in a very simple and short article. The study of genetics can be as involved as you want it to be. It is a very complex subject, which makes it impossible for me to fully explain in a short article, nor do I have the knowledge to do so. Hopefully this article will help in giving you a general understanding of the subject, and will encourage you to further discover the wonderful world of genetics through the different sites available on the Internet today. Please visit our links page which will direct you to some of these sites as starting points to a whole new adventure that will enhance your knowledge and appreciation for these beautiful little parrots.

Notice that Green is the primary color displayed in all Psittacine species. So you will also notice that all Agapornis species also have green colored body feathers in the wild. The peach face is no exception to this rule so in their natural form these beautiful little guys have a grassy green body color, with a deep red face, forehead and bib. The rump colors are aqua blue, feet are dark gray, and eyes are black. Mutations are rarely found in their natural wild habitat because even when they appear, they are lost through generations of breeding with other wild type, or, non-mutated partners.

However, many mutations have been developed over the years, mostly in various aviaries around the world. You will also learn that mutations are all a result of changes within the basic feather structure of the plumage. It is therefore important to have an awareness of the basic feather structure to understand the basic wild color form, and how it can be altered to give various mutations.

To help you understand how genetics work and to be able to determine the possible offspring’s from different pairings I will divide this article into 6 main areas of discussion. I truly think it is important that you acquire a general understanding of each of these sections. At the end of this article, for those who want to read even more, I will place suggested links to different sites that provide a more in depth study on the subject. The following are the areas of discussion we will explore.

1-     Feather structure

2-    Types of mutations

A-   Psittacin mutations

B-    Eumelanin mutations

C-    Alterations in eumelanin distribution

D-   Alterations in feather structure

3-    Genes and Chromosomes

4-    Modes of inheritance

5-    Basic applied genetics

FEATHER STRUCTURE:

Again, it really helps to have a reasonable understanding of how a feather barb is structured. Mutations are a result of changes within the feather structure so knowing the main parts of a feather barb should help in your quest to get an overall understanding of genetics.

Here is a diagram showing the cross section of the basic contour feather barb. Note that there are different parts to the overall structure of the barb. It isn’t just a solid object that happens to be green. You will notice as we go further, that the color green is achieved by combining the different elements of the feather structure. In other words there are several parts to the feather, and they all play a different role in obtaining the color green. Now lets look at the important parts of the basic feather structure, which are not only important in how the color green is formed, but also how mutations are formed. This is where everything that effects color happens. You will learn that what you see as the color green, is really the combination of Yellow, brown, and black pigments, with what is called blue interference. Here are the important parts you should be aware of.

Cortex: This is the outer ring. This part of the barb is very important as this is the part of the feather that has the yellow pigments called psittacins.

Spongy Zone: This is the middle layer which, when it interacts with sunlight, will produce blue and violet interference.

Center or medulla: This area contains the black and brown pigments called eumelanin, which surrounds tiny holes called vacuoles.   

Changes to the physical structure of the different layers within the barb are what generate the different mutations. For example decreasing the thickness of the cortex will decrease the amount of yellow psittacin in the feather. Also, reducing the amount of eumelanin in the center medulla will affect the interaction or blue interference of the spongy zone.

The coloration of birds is derived from three kinds of pigmentations within the feather stem. In Agapornis I will mainly talk about two of these pigmentations, melanins (black eumelanin, and brown phaeomelanin pigmentation), and the psittacins (red and yellow pigmentation). These pigments are also influenced by the feather’s ability to disperse light beams within its cloudy zone, which is referred to as blue interference. It’s also important to understand that what you perceive as the color of a feather is a combination of the colors from the light source that are not absorbed by the feather, or, that are reflected back to you from the feather. Lets look at what this means. First you start with all the colors of the rainbow (found in natural sunlight), and, expose them to any object (in this case the feather barb). When all the colors reach the object, some of the colors are absorbed by the object, while others are reflected back (sort of like a mirror). The colors that are reflected back are the colors that you visually see. So a yellow object is one that absorbs all the colors it is exposed to except the yellow. So changes in the composition of the feather structure will also produce changes in the colors that are either absorbed or reflected.

As mentioned above, the wild form peach face has a green colored body. The color green is produced as a result of the interaction of the effects of the eumelanin (black and brown pigments), with the blue interference (light beam dispersment of the feather structure), and psittacins (yellow pigments). If you alter the percentages of any of the pigments, the color will change. Again, as mentioned, color variations are a result of the interaction of the eumelanin and psittacins pigments with the blue interference within the feather structure itself. These coloration variances are due to the changes in the different percentages of, absence of, and or presence of the different pigments. These changes affect the way that light is either absorbed or reflected off the feathers themselves, thus resulting in basic color changes.

It’s important to keep in mind that combining yellow and blue pigments forms the color green, so if you remove the yellow pigments, only the blue remains, if you remove the blue, only the yellow remains. For example, a blue bird is produced when there is a complete or partial reduction of the yellow psittacin in the feather. Ino is the result of an almost complete loss of the black eumelanin and it’s resulting reacting with the blue interference of the spongy zone resulting in a yellow plumage.

With the wide use of the Internet today, the choice of mutation names has become a subject of much discussion because different countries use different names for the same mutation or color. I do believe that standard names will help stop the confusion in the avian world in the proper identification of the different mutations. For this reason I will use the names that are presently suggested by an international group of scientists, with the commonly found (North American) names in brackets.

PSITTACIN MUTATIONS:

When we talk about psittacin mutations we are referring to mutations that are a result of a reduction in the amount of pisttacin within the feather structure, whether partial, or total. In other words, and in simple terms, the reduction (either partial or total) in the amount of yellow pigmentation from the wild green color form. The result is a partial blue or total blue bird. Remember that green is a combination of yellow and blue, so if you remove or alter the percentages of each, the color changes. In this case the more yellow that is removed, the bluer the resulting color will be.

In the peach face mutations only a partial reduction in the yellow psittacin is possible therefore there are no true blue (pure blue) peach face lovebirds. There will always be a trace of yellow in any of the blue mutations, which will always give a certain amount of green color to the plumage. However a true blue mutation does exist in the eye ring species (fisher's, black masked, nyasa) where a total loss of psittacin is possible.

When I say partial reduction I am referring to a reduction of less than 100% of the yellow pigmentation. There are 2 basic forms of the blue mutation in the peach face lovebird. They are both alleles of the blue-locus. The Aqua (Dutch Blue), and, the Turquoise (White Face). The difference in the two mutations is in the amount of (or percentage of) psittacin (yellow) altered or removed. In both cases, the facial colors are also affected. The result is a total loss in the red pigments within the facial area, and, a partial reduction in the forehead colors. 

The AQUA (Dutch Blue) is a bird with approximately 50% psittacine reduction (half of the yellow remains) within the cortex of the feather producing a noticeable bluer body color (than the normal green) with a creamy light gray face and bib, and a cantaloupe colored forehead.

The TURQUOISE (White Face) is a bird with a 50% psittacine reduction dorsally, and a 90% psittacine reduction ventrally. It has a slightly bluer body color, with a cleaner white face, bib and forehead.

The APPLE GREEN (Seagreen) is often referred to as another blue mutation. That is not the case, but rather, it’s the result of combining the two previously mentioned blue forms (one Aqua parent paired with a turquoise mate), which produces an intermediate form. This combination is possible because both the Turquoise and the Aqua are alleles of the blue-locus, so they are called multiple alleles. These birds have the body color somewhere between the Aqua (Dutch Blue) and the normal Green bird but will retain the facial features of the Aqua (Dutch Blue). It is sometimes very hard to distinguish the Seagreen from the Aqua, especially if dark, and, or violet factors are involved.

The ORANGE FACE is the result of a different ratio of red and yellow pigments within the facial mask. The resulting affect is an orange mask (and tail dots), rather than red in the wild-type birds. The effect is not as dramatic (and a lot less desirable) in blue birds as it only affects the forehead color changing it from a cantaloupe to a very light to yellowish peach colored forehead.

EUMELANIN Mutations:

As noted above, the interaction between the eumelanin and the blue interference of the spongy zone is what produces the blue color in the feathers. A Eumelanin mutation refers any mutations that are a result of a complete, or, partial eumelanin (blue) reduction within the feather, resulting in a yellowier, or, totally yellow body color. The eyes and feet colors are also affected, but the facial features remain the same.

The INO mutation is a bird with a total reduction of eumelamin in the feather structure thus resulting in a bird with a totally yellow body color, white flights feathers, and a white rump (with a hint of pale blue). The eyes are red, and the feet are pink.

The PALLID (Australian cinnamon, Par-Ino) is a multiple allele to the ino-locus. It shows a practically total blue reduction (sort of in between the cinnamon and the ino, but a lot closer to the ino) giving it a yellow lime color. Feet and legs are pink, and, the eyes are plum colored.

The CINNAMON (American cinnamon) mutation has, because of its brown pigments instead of black, a lesser ability to absorb light thus resulting in a paler green body color than the normal bird.

The CINNAMON-INO OR CINNAMON-PALLID (Lacewing) is an interesting mutation, as it combines the (American) Cinnamon with any of the 2 Ino forms (Ino, or Pallid). In rare cases a crossing-over of (3% of the offspring's) both genes will appear, and, co-exist on the same location on the chromosomes rather than on separate locations as in a normal case. They are very similar in appearance to the Pallid. The green form will be yellow with a slight tinge of green on the wing coverts and a slight bluish rump.  The flight colors should be between the white flights of an Ino (white), to the brownish flights of the cinnamon or the grayish flights of the Pallid depending of the type of inheritance. Eyes are red.

The BRONZE FALLOWS (West German) is a mutation that alters the color of the eumelanin from brown to a gray brown. The granules of the eumelanin are also smaller in size that the normal form. This results in a mutation that shows a body color similar to the cinnamon, with lighter colored flights, red eyes, and, pink legs and feet. The back of the head is paler and the rump colors are a duller blue than the wild form.

The PALE FALLOWS (East German) is similar to the Bronze Fallow but has a lesser amount of grayish brown eumelanin resulting in an almost yellow (with an olive shade) bird.

Alterations in eumelanin distribution:

EDGED DILUTE (American yellow or Golden Cherry) is affected in much the same way as the cinnamon, but only on the outer edge of the feather. It’s a result of normal eumelanin distribution on the outer edges of the feathers, with a 60% eumelanin reduction on the rest of the feather (only the flight and feathers and wing coverts have the edged affect). This gives a two-tone effect, which results in a marbled pattern to the feathers. The rest of the body also has a eumelanin reduction, which gives it a pastel look. The rump colors are a washed blue, and the feet and legs are light gray.

DOMINANT PIED: factored birds show a complete loss of eumelanin, but only in selected areas of the feathers. The pied affect can range from a barely noticeable yellow blotch on the body feathers, or a single (or partly) white flight feather, to a completely yellow bird that looks like an ino and everything in between. The rump and facial colors are not affected by the pied gene therefore retaining the colors of the normal bird.

RECESSIVE PIED: was originally called Australian yellow. It shows an almost complete loss of eumelanin (95%), which results in an almost completely yellow body color. Even the rump colors are yellow with a slight green tinge to the upper portion.

Alterations in eumelanin and psittacin distribution:

The OPALINE is a uniquely new mutation (USA 1997), which extends the red (psittacin) mask to the back of the neck (rather than stopping at the top of the forehead). The body color is a duller green, and the rump colors are practically completely green. The black and blue tail dots have also been replaced by red markings.

Alterations of Feather Structure:

The VIOLET FACTOR  occurs due to an alteration of the structure of the spongy zone around the medulla of the feather barbs. This results in darkening the plumage with a violet color tone. The rump colors are also affected by the violet factor as it gives the rump a violet blue color. It is most noticeable when received from both parents, and, when a dark factor is also included giving the rump a beautiful dark violet look. Although the violet is also visible in the body feathers of the green form birds, it is most noticeable in blue mutation birds. The Turquoise (white face) mutation displays the most violet because it is the bluer of the 3 forms. Mutations involving violet factors are identified by adding the terms SF (single factor) Violet, or, DF (double factor) Violet to the phenotype. Example: SF Violet Normal Green, DF Violet Aqua, Sf Violet Turquoise, etc.. 

The DARK FACTOR occur because of the narrowing of the spongy zone, resulting in darkening of the entire plumage. One, or a single dark factor (received from one parent only) darkens the body plumage and gives the rump colors a darker royal blue color rather than the paler aqua blue of the normal bird. The existence of 2, or double dark factors, would display a further darkening of the overall body plumage. Green form birds would show a very dark green look, whereas the blue form birds would become practically gray (again, the turquoise would be the grayer of the 3 forms). The rump colors will always be gray regardless of the forms. Mutations involving dark factors are identified by adding the terms Dark (single dark factor), or, Olive (double dark factor) for Green form birds, and, Dark (single dark factor), and, Mauve (Double Dark factor) to the phenotype. Example: Dark Green, Olice Green, Dark Aqua, Mauve Turquoise, etc.. 

Genes and Chromosomes:

Have you ever wondered why every living human is somewhat the same, but yet every single human ever conceived is different in some ways, even so called identical twins? And have you ever wondered why there are so many similarities within the same families? Do you have your fathers, or, your mothers nose, eyes, bone structure, skin tone, etc., or, even some of your grandparents features? It’s all a product of genetic modifications. You are all a product of both your parents.

Every living being is comprised of living cells, which are the smallest living organisms on our body. We are a combination of billions and billions of cells that vary in size and structure depending on their function.

The nucleus of each living cell contains chromosomes. Each chromosome consists of a pair of long string like bodies lying close to each other. The number of chromosomes within the nucleus of the cells depends on the species in question. The roseicollis (peach face), as an example, has 23 pairs of chromosomes (or 46). Chromosomes are where you will find nucleic-acid molecule structures called “Genes”.

The “gene” is the fundamental building block in genetics. Its molecular structure is responsible for every living being’s structural make-up.  All occupy well-defined and well-organized places, called “loci” (think of location), along the string like structure of the chromosomes. Each gene is located on a specific “locus”, which is the specific location that each gene occupies.  It is important to know that each gene is responsible for, and, is designed to do one specific task. Therefore it is the combination of thousands of genes that form the genetic make up of each chromosome.

Now that we know that all genes are combined to create chromosomes, which in turn form the basis of every living cell, lets look at how they all work together.

We should know that every living being is the product of the union between male and female cells. The union of two reproductive cells forms an egg. The one from the male is called the spermatozoon (sperm), and the other from the female, called the ovum. What happens is that each of the parents contributes a half of their genetic make-up. It is therefore important to note that all chromosomes come in pairs, and that each pair is “homologous” to one-another. What this means is that each gene is located in the same corresponding location as the corresponding gene within the pair of chromosomes. Chromosome to chromosome, gene to gene (locus to locus). These pairs of genes, which are located locus to locus, are known as “alleles” (think of allies). This is important so that each pair of genes can exchange their genetic make-ups. Knowing that each gene has a specific task, it’s important that they be “alleles” to one another so that the exchange of information from both parents can be properly made. So the union of the father’s gene with the mother’s gene creates every specific task within the body of all living beings.

Occasionally, some genes suffer abnormalities, or alterations. Most of these changes within the gene structure occur as a spontaneous natural phenomenon, although some are created in laboratories. These variations are called “mutations”, but, “Only if they can be inherited”.

Modes of Inheritances:

Even if a bird has received a particular mutant gene from one of the parents, it may, or may not be visually seen in the offspring. Some mutations have to be inherited from both parents in order to be visually seen. 

Lets look at one example where a particular pair of genes is responsible for the development of the lutino (ino mutation of the normal green form). If one of the genes suffers an error rendering it incapable of producing melanin, then the overall melanin production within the allele (pair of corresponding genes) will be reduced.  However, melanin continues to be produced under the control of the normal (non altered) allele gene resulting in no detection of visual changes or alterations in the offspring’s colors. Now if two of the altered genes appear in the same bird (received from both of the parents), it eliminates the possibility to produce any melanin at all (both genes are unable to produce any melanin). As we’ve seen at the beginning, the elimination of all the melanin within the feather results in an all yellow-bodied bird, or, a lutino. 

The study of how genes interact within the pair (alleles) is referred to as modes of inheritance.

We will look at 3 modes of inheritance: Autosomal Dominant, Autosomal Co-Dominant, Autosomal Recessive, and, sex- linked Recessive.

Autosomal Dominant: A dominant gene will always express itself regardless of whether it’s paired allele gene is the same or has been altered. Its presence (whether single or double) will always be visual. If you go back to the ino example given above, where the presence of the non-altered gene was sufficient to produce the melamin levels necessary to produce the normal phenotype (wild form colors).  The obvious dominant gene is the normal wild form. In other words if the green (wild form) gene is present, 

Autosomal Co-Dominant (or Incomplete Dominant): means that the presence of any of these mutant genes will have a visual effect. The appearance of a single factor (heterozygous) will be different than a bird with a double factor (homozygous).  Because it isn’t completely dominant, the presence of both mutant genes is required to give the full effect to the feather form, and resulting color change. However the presence of only one affected gene will produce an intermediate effect to the structure and color. For example, the dark factor is visually different when it is inherited from only one of the parents  (cobalt) or both (mauve). The presence of only one dark factored gene gives an intermediate (not as dark) effect when compared to the presence of two altered genes. The same inherited effect is seen with the violet factor.

Autosomal Recessive: means that it has to be inherited from both of the parents in order to be visual. All blue forms are recessive as well as the - ed mutations.

Sex-Linked:  There are several genes that do not manifest themselves in the usual manner. In some offsprings we can observe that certain phenotypes appear predominantly in females, rather than males. Genes exist on both autosomal and on sex-chromosomes. As mentioned earlier, genes come in pairs. All pairs, with the exception of one pair, are identical, and are called autosomal chromosomes. The one pair that is different in cocks and hens (XX and XY) is called the sex-chromosomes pair. Genes that are linked to sex are called sex-linked. The letters X and Y identifies sex chromosomes. The male has 2 X chromosomes and the female has an X and a Y chromosomes. - ed genes only exist on the X chromosomes.  For this reason (because the female has only one X chromosomes, the other being the Y) it only has to inherent the gene from one of its parents, whereas the male (having 2 X chromosomes) has to inherit the genes from both of the parents. Therefore the chances of producing females in the sex-linked mutations are much greater. If a female has the gene it will be visual, but the male still has to receive the gene from both parents. 

There are several sex-linked mutations in the peach face lovebird. They are the Ino, the Cinnamon (American Cinnamon), the Pallid (Australian Cinnamon, Isabel, Par-Ino) that is an allele of Ino (the cinnamon is not an allele of the Ino), and, the Opaline.

Here is a list of the different mutations with their corresponding modes of inheritance, and their genetic symbols. The genetic symbols are used to identify the different mutant genes from their non-mutant or wild form genes. This will be very useful in the next section where we talk about applied genetics.

Peach-Faced Lovebird Mutations

Eye-Ringed Lovebird Mutations

Basic applied genetics:

Now that we’ve studied how mutations are derived from the normal wild type birds, let’s look at how this theory is applied. What will the babies from a specific pairing look like? What are the percentages of each possible mutation from this specific pairing?

The first thing to remember is that the mutant genes that I’ve talked about can, and, do co-exist. In other words you can have combinations of several of the above mutations. (Ex: a double dark double violet Turquoise (whiteface) Aqua pallid (Australian cinnamon) pied, or, a dark single violet factor green, or a aqua (Dutch blue) pied, and so one, and so one.... There are hundreds of combinations.

In order to be able to predict the different off springs from a specific pairing, you have to be able to identify and separate the different mutant genes present in both of the parents.  Sometimes the mutations are visible, and, sometimes their not (the presence of only one mutant recessive gene). It is also important to remember that all genes that affect color come in pairs.

Mendel’s Law: When the segregation of a pair of genes occurs, the gametes are transmitted to the off-springs at a rate of 50%, or, each of the 2 genes forming a pair will be transmitted to the descendants in an equal amount of times (50%/50%). So we are dealing with the issue of probability. We’ve talked about coloration being the result of genetic interaction. Mendel’s law is a means of identifying all possible combinations (different off springs) within a specific clutch, along with the probable percentage of each occurrence. It is also important to note that the law of probability (that’s what we’re talking about here) requires a very large number of samples to be valid.

We now know that each parent will produce, and pass to each descendent, a gamete that carries only one allele of each pair of genes. We also know that the male has 2 X chromosomes and the female has an X and a Y chromosomes. Any of the genes can be passed on to any of the sex chromosomes (X or Y). So now it’s a matter of identifying and separating all the possible genes and placing them in Mendels model. Let’s look at the simples of examples, that being the pairing of 2 wild form birds. We know that there are no mutant genes, so both pairs of genes will have identical alleles. The male will have two normal green (or wild form) genes (bl ⁺, bl ⁺), and so will the female (bl ⁺, bl ⁺).  Therefore the following are the only possible combinations.

Hen: X bl ⁺, Y bl ⁺

Cock: X bl ⁺, X bl ⁺ 

The first thing you have to do is place all possible combinations in the grid as shown below. All male combinations are placed on the top row, and the female combinations in the first column.

Now fill the inner spaces with the corresponding genes as shown below.

The four inner blocks represent the possible offsprings for this pairing. Note that there are only two different combinations

X bl ⁺ Y bl ⁺, and X bl ⁺ X bl ⁺       

The difference is only in the sex chromosomes, therefore you have a male and a female. Also there are no mutant genes present so all babies will be normal green. This is to be expected. All babies will be normal green with half being cocks and half being hens.

Let’s look at another simple example where we have a green/aqua hen paired with an aqua male. We know that we have 2 different genes at work, one being the Green (non-mutant or wild-type), and the Aqua (mutant gene). We can identify both parents by their respective gametes, being (bl ^aq, bl ^aq) for the male (2 mutant Aqua genes), and, (bl ^aq, bl ⁺) for the hen (1 mutant Aqua gene, and one non mutant, or normal gene). Therefore the following are the list of possible combinations that can be passed on to the offsprings.

Hen: X bl ^aq, Y bl ^aq, X bl ⁺, Y bl ⁺

Cock: X bl ^aq, X bl ^aq

Notice that there are 8 different possible combinations identified for this pairing, half of which are hens (XY), and the other half are cocks (XX). Also note that there are only two distinct combinations for colour (bl ^aq bl ⁺, and bl ^aq bl ^aq).

From this we can conclude that the babies will look like their parents. Half will be Aqua, and half will be normal green split to Aqua. Of these half will be hens and half will be cocks.

Now lets look at what happens when you pair two normal greens birds, both split for Aqua. So both hen and cock would have the same gametes (bl ^aq, bl ⁺).

Hen: X bl ^aq, Y bl ^aq, X bl ⁺, Y bl ⁺

Cock: X bl ^aq, X bl ⁺

Other than the fact that half the offsprings are males, and the other half are hens, there are 3 different combinations observed.

Bl ^aq bl ⁺,  bl ⁺ bl ⁺, and bl ^aq bl ^aq

Now lets look at the percentages for each of the 3 phenotypes from the 8 possible offsprings,

1/2 are Normal Green/Aqua (bl ^aq, bl ⁺)

 1/4 are Normal Green 

 1/4 are Aqua (bl ^aq bl ^aq).

OR

1/8 – male Normal Green (X bl ⁺ X bl ⁺ )

1/8 – male Aqua (X bl ^aq X bl ^aq )

1/4 - male Normal Green/Aqua (Xbl ^aq, Xbl ⁺),

 1/8 – hen Normal Green (X bl ^aq Y bl ^aq )

1/8 – hen Aqua (X bl ⁺ Y bl ⁺ )

1/4 – hen Normal Green/Aqua (X bl ^aq Y bl ⁺),

Now lets look at what happens when we combine more than one mutant gene. If we add a dark factor to both parents in the last example we will have a pairing consisting of both parents being “Dark (Jade) Green/Aqua”. So both hen and cock would have the same gametes (bl ^aq, bl ⁺) + (D ⁺, D).

Again if you look at all the possible combinations we get the following.

Hen: X Dbl ^aq, Y Dbl ^aq, X Dbl ⁺, Y Dbl ⁺ , X D ⁺bl ^aq, Y D ⁺bl ^aq, X D ⁺bl ⁺, Y D ⁺bl ⁺

Cock: X Dbl ^aq, X Dbl ⁺ , X D ⁺bl ^aq, X D ⁺bl ⁺

Again half of the combinations are hens, and, the other half, are cocks. Notice that although there are 32 blocks filled, there are only 9 phenotypes observed.

(D ⁺bl ⁺, D ⁺bl ⁺) – Normal Green, (D ⁺bl ⁺, Dbl ⁺) – Dark Green, (Dbl ⁺, Dbl ⁺) – Olive Green

 (D ⁺bl ^aq, D ⁺bl ^aq) – Aqua, (D ⁺bl ^aq, Dbl ^aq ) – Dark Aqua, and, (Dbl ^aq, Dbl ^aq) – Mauve Aqua

(D ⁺bl ⁺, D ⁺bl ^aq) – Normal Green/Aqua, (D ⁺bl ⁺, Dbl ^aq) – Dark Green/Aqua, (Dbl ⁺, Dbl ^aq) – Olive Green/Aqua

The 32 blocks only become important when identifying percentages of each offspring.

1/32 – Normal Green cocks, 2/32 – Dark Green cocks, 1/32 – Olive Green cocks

 1/32 – Aqua cocks, 2/32 – Dark Aqua cocks, and, 1/32 – Mauve Aqua cocks

2/32 – Normal Green/Aqua cocks, 4/32 – Dark Green/Aqua cocks, 2/32 – Olive Green/Aqua cocks

1/32 – Normal Green hens, 2/32 – Dark Green hens, 1/32 – Olive Green hens

 1/32 – Aqua hens, 2/32 – Dark Aqua hens, and, 1/32 – Mauve Aqua hens

2/32 – Normal Green/Aqua hens, 4/32 – Dark Green/Aqua hens, 2/32 – Olive Green/Aqua hens

Now lets add one violet factor to each of the parents mentioned in the above example. Again both hen and cock would have the same gametes (bl ^aq, bl ⁺) + (D ⁺, D) + (V ⁺, V).

For this example we’ll forget the X & Y chromosomes and just concentrate on the possible phenotypes.

Cock – (bl ^aqD ⁺V ⁺), (bl ^aqD ⁺V), (bl ^aqDV), (bl ⁺D ⁺V ⁺), (bl ⁺D ⁺V), (bl ⁺DV)

Hen- (bl ^aqD ⁺V ⁺), (bl ^aqD ⁺V), (bl ^aqDV), (bl ⁺D ⁺V ⁺), (bl ⁺D ⁺V), (bl ⁺DV)

From this pairing we know have the following 27 phenotypes (27 cocks, and, 27 hens).

Normal Green, Dark Green, Olive Green

SF Violet Normal Green, SF Violet Dark Green, SF Violet Olive Green

DF Violet Normal Green, SF Violet Dark Green, DF Violet Olive Green

Aqua, Dark Aqua, Mauve Aqua

SF Violet Aqua, SF Violet Dark Aqua, SF Violet Mauve Aqua

DF Violet Aqua, DF Violet Dark Aqua, DF Violet Mauve Aqua

Normal Green/Aqua, Dark Green/Aqua, Olive Green/Aqua

SF Violet Normal Green/Aqua, SF Violet Dark Green/Aqua, SF Violet Olive Green/Aqua

DF Violet Normal Green/Aqua, DF Violet Dark Green/Aqua, DF Violet Olive Green/Aqua

By now you should be able to calculate the percentage for each of the phenotypes on your own by following the above examples.

Now lets look at what happens when we add a - ed mutation to the mix.

It’s important to remember at this stage that the - ed gene only exists on the X chromosome. It doesn’t exist on the Y chromosome as seen earlier. Again it’s for this reason that these particular mutant genes are called - ed.

You should also note that it is important to add X & Y sex chromosomes to this exercise.

Lets look at the Ino mutant gene and how it is transferred to its offsprings. If we pair a Lutino (Green Ino) hen with a Normal Green cock you will have the following results.

Cock – X (ino ⁺ bl ⁺), X (ino ⁺ bl ⁺)

Hen – X (ino bl ⁺), Y (bl ⁺)

In this example we observe that half the offsprings are Normal Green/Ino males, and half Normal Green hens.

Now lets look at a Green Ino hen paired with a Normal Green/Ino cock.

Cock – X (ino ⁺ bl ⁺ ), X (ino bl ⁺)

Hen – X (ino bl ⁺), Y (bl ⁺)

From this pairing we get :

1/4 Normal Green/Ino male

1/4 Lutino male

1/4 Normal Green hen

1/4 Lutino hen

Now lets look at pairing a Lutino male and a Normal Green hen.

Cock – X (ino bl ⁺), X (ino bl ⁺),

Hen – X (ino bl ⁺), Y (bl ⁺)

From this pairing we get:

1/2 Normal Green/Ino males

1/2 Lutino hens.

The interesting thing to note in this pairing is the fact that all babies can be sexed by mutation. Note that Normal Greens babies are all cocks, and that all lutino babies are hens. I short, any Ino babies that are produced from a pairing in which the hen is “not” an Ino, will always be hens. This is always the case for all - ed mutations.

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