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Genetics

 Basic Genetics
Platinum & lutino
 
Mutation definitions  

    Basic Genetics

By Frank De Luca

You don’t have to be totally switched on with genetics to be able to predict the outcome of a particular pairing of birds. To improve your flock all you need is a basic knowledge and a little insight and once you have read this article a few times you will find it comes to hand pretty quickly!

In genetics there are basically 3 types you need to understand with 2 of them common, to be able to confidently predict pairing outcomes and these types are as follow:

1) Sex Linked
2)
Recessive
3)
Dominant

Gene 1 - The Sex Linked Gene

The first gene the Sex Linked variety is very simple to understand without going into all the formulas of how and why we achieve the results as not to confuse you, I can honestly say I wish I had a dollar for every time I was asked “What will I get If I breed this male to this hen”? Following these simple guides you can now work it out for yourself.

A Sex Linked gene is not complex it is a gene that represents most of our every day varieties and in most cases this covers Lutino, Cinnamon, Platinum and Pearl. You might say that’s what I have! Well you can predict the outcome and in some cases also the sex of a Sex Linked pairing and this is how it is applied in simple terms.

Males that are the above sex link varieties mentioned when bred to a hen that is not of the same variety will always produce sibling hens the same variety as dad! For eg A Lutino cock will produce a Lutino hen sibling! The same result will appear with the other mentioned varieties! Getting there slowly, if confused read that bit again slowly before you read on. Moving on so what if Mum is also a Lutino then naturally all siblings born will be Lutino!

So now we know that a Sex Linked cock will produce Sex Link hen siblings the same as dads’ variety. What about male siblings born from the same pairing what will they be? They will be Normal for the mutation involved, an eg is the Cockatiel the normal Cockatiel is grey bird! So in the nest from the same pairing where dad is Lutino and mum isn’t we have 4 siblings 2 with Lutino (yellowish tones) and 2 with grey normal tones, this represents 2 hens and 2 cock siblings a great way to sex your clutch which can be very important for those who are wanting to hand rear the young!

So what next? You ask simple you have heard the terminology “split-to” this term identifies a hidden gene that is carried but isn’t visible in appearance, for instance the young male siblings from our Cockatiel pairing that were born normal grey are also now genetically “split to Lutino” and we write that as Normal grey/ lutino a forward slash in genetic terms indicates the split factor confused! Have another read.

So your next question is “What about if dad is lutino and mum is cinnamon” what happens then? this is also easy to calculate as the breeding results will still be the same as mentioned where all hens born will be Lutino and all males born will be Grey Normal but instead of males being split to Lutino only the males will also be split to Cinnamon but still appear grey a Multi-split! In genetic terms Grey Normal/Lutino/Cinnamon or abbrev Nml/lut/cinn so now you know what that terminology means. The only other simple important factor to remember is that hens CANNOT BE SPLIT to a Sex Linked variety.

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Gene No 2 - The Recessive Gene

The Recessive gene is probably the most important gene as with most mutations and their varieties this gene normally represents a unique feature such as individuality, but has stunning results when combined with a Sex Linked gene. The Recessive varieties in Australian Birds are Countless but for the exercise we will concentrate on Cockatiels which we are most familiar with! (Well I am anyway)

The recessive varieties in Cockatiels are; Pied, Whiteface, Silver, Fallow and Pastelface to some extent. Remembering that the same is true for all recessive varieties in other forms of Aviculture which needs to inherit a gene from both parents to reproduce itself visibly!

So now you ask me “I have a Whiteface male what happens when I put him to Normal Hen”?

In simple terms nothing happens all siblings born will be normal like mum! But why? Because to produce a recessive variety likes a Whiteface Cockatiel both parents need to be visually Whiteface or at the least split to Whiteface. Not sure read that bit again over and over until it sinks in!

Can a hen be split to a recessive gene? Yes it can so to define a recessive variety both parents need to carry it in their make up or be visually that gene to produce siblings of the same mutation!

So what happens to the genetics of the above pairing? Well it would read like this all siblings born will be normal grey but all siblings will be split to the Whiteface gene Normal Grey/Whiteface or in brief Gry/wface! What happens if mum is also a Whiteface? Well simple, all siblings will be Whiteface! Now the term Multi Mutation pops up every now and then so what does this mean? This means that a bird carries more than one gene visibly such as a Whiteface Pied, Two recessive genes from each parent combined to produce a unique bird. What about if we now get the Whiteface Pied and add on Pearling for the exercise we end up with a Whiteface Pearl Pied a genuine simple Multi Mutation variety with absolute stunning features incorporating two recessive genes and one sex linked gene, so as you can see the outcome of multi mutating can become very complex but also very rewarding!

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Gene No 3 - The Dominant Gene

Last but not least is the Dominant and Co-Dominant gene. In most cases the wild form of variety is a dominant gene for e.g. in cockatiels the grey normal is recognized as dominant to a recessive variety meaning if you place a grey normal cockatiel to a recessive Whiteface cockatiel the dominant gene will express itself and produce all grey normal offspring.

The latest mutation to hit our shores is the Pastelface gene or properly termed as Par blue which is also a dominant gene! but only dominant to the whiteface gene, therefore in every Pastelface is carried the Whiteface gene but not so vice a versa! These types are sometimes called Single factor varieties, confused not really important unless you are breeding Pastelface and all you need to remember is every Pastelface is split to Whiteface but a Whiteface is not split to Pastelface.

By pairing a Pastelface to a Whiteface the offspring will be 50% Pastelface and 50% Whiteface. Pastelface can also inherit a Double factor variety which is achieved by pairing SF-Pastelface to S-F Pastelface some 25% of this pairings siblings will be Double- factor Pastelface which is usually identified by the lighter tones or by future test breeding. Just to confuse a little more when a D-F Pastelface is paired to Whiteface all siblings born will be S-F Pastelface.

Take your time to read over and over all genetic related articles as it will slowly sink in making breeding programs come to fruition and more enjoyable instead of the guessing game that usually starts with “What do I get if I breed this male with this female”

Please note the above is only a quick guide to genetics which can be very complex but I hope that you can take a little from here and put to practice some formulas that will enhance your flock,

“Bent Tails” Frank Hillcrest Cockatiels

© Hillcrest Cockatiels 2005. All rights reserved.

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Platinum and Lutino
Genetic Interaction:

THE PLATINO EFFECT!

© Mike Anderson

In Volume 3, Issue 1 of The Australian National Cockatiel Society Journal, January-February 1996, I put forward a theory that when Platinum and Lutinos were bred together, that all offspring would be coloured birds, and that I believed the Platinum and Lutino genes occupied the same chromosomal location. After three and a half years of further experimentation and also observing the results from other breeders, I still hold the same view.

Platinum Most cockatiel breeders will be aware that Platinum and Lutinos follow the normal sex-linked genetic pattern. This is generally true, but not when you breed a Platinum and a Lutino together! When bred together, irrespective of which bird is the cock and which is the hen, all offspring are coloured, including the cocks, which we would normally expect to be grey birds split for Platinum and Lutino.

Platinum
There is still a lot of confusion about Platinum and Lutino genetic interaction, and now is probably a good time to review our knowledge of these two birds, and to outline in practical terms the results of breeding them together.
Most cockatiel breeders will know that Lutinos are sex linked and basically light yellow in colour.
For the benefit of those readers who may not be familiar with the Australian Platinum, they are also a sex-linked mutation. Their general physical characteristics are briefly described as follows:

  • Light, smoky grey back, flights and tail, with flights sometimes verging on a grey/brown colour

  • Off white coloured chest

  • Flights and tails are characteristically always a darker colour to other feathers

  • The underside of tail feathers in mature cocks is usually a brown/ chocolate colour

  • Light-coloured feet and beak

Whilst there appears to be no information about the origin of Platinums in Australia, I have traced their presence back to at least the 1970s, and have owned and bred Platinums since 1988.

Before we examine what happens when we breed these two sex-linked mutations together, I would like to introduce and explain a descriptive term I have coined to describe an unusual offspring produced by the aforesaid union. As the bird in question has no official name, or logical genetic label that can accurately describe it in simple terms, I shall refer to it as a "Platino". The characteristics of a Platino are described as follows:

Sex: They are always cocks

Colour (Phenotype): An intermediate colour between Lutino and Platinum. Young Platinos can be so light as to be mistaken for Lutinos. With maturity they acquire more pigmentation, especially to the flights and tail, but never approach the depth of colour of normal Platinums. (N.B:- These birds are definitely not just Lutinos with a lavender wash!).

Genetic Makeup (Genotype): They carry one gene only for Lutino and one only for Platinum. In genetic symbols they would be denoted as XLXP, with X representing the male chromosome, L the Lutino gene & P, the Platinum gene. A full Platinum cock would be denoted as XP XP, and a Lutino cock as XL XL.

Let us now examine what happens when Platinum and Lutino are bred together:

Pairings

Platino 1. Lutino cock to Platinum hen

  • All cocks are Platinos

  • All hens are Lutinos

2. Platinum cock to Lutino hen

  • All cocks are Platinos

  • All hens are Platinums

3. Platino cock to Platinum hen

  • 50% of cocks are Platinum

  • 50% of cocks are Platino

  • 50% of hens are Lutino

  • 50% of hens are Platinum

4. Platino cock to Lutino hen

  • 50% of cocks are Lutino                                        Platino

  • 50% of cocks are Platino

  • 50% of hens are Lutino

  • 50% of hens are Platinum

For contrast, a Platino cock paired to a normal hen would produce:

  • 25% Grey cocks split for Lutino

  • 25% Grey cocks split for Platinum

  • 25% Lutino hens

  • 25% Platinum hens

To look at it another way, a Platino is simply a male bird that is split for Lutino and Platinum, as would be the expected result from any combination of breeding Lutino and Platinum together. It is simply a "DOUBLE SPLIT". If we forget that a Platino is coloured, and think of it as a normal split to Lutino and Platinum, it is much easier to understand the above breeding results.

  • 21 visually normal cocks (but split either Platinum or Lutino)

  • 15 normal-coloured Platinum hens, and

  • 12 Lutino hens.

In the above example, as in every other case I've observed, the Platinum and the Lutino gene have always been passed on singularly, which leads me to suspect that the respective genes (or alleles) occupy the same chromosomal position. My understanding of genetics is that genes at the same locus on paired chromosomes cannot get together on the one chromosome. If this were possible, you would have, for example, Cinnamon cocks passing on one of their two sex determining chromosomes with a double dose of Cinnamon genes, and the other devoid of any Cinnamon genetic material at all. This of course does not happen, and that's why we can always guarantee any bird bred from a Cinnamon cock must inherit a Cinnamon gene.

If we accept that Platinum and Lutino occupy the same chromosomal location and interact to produce an intermediate colour in cocks, the following facts can be concluded:

  • Cocks of normal grey appearance cannot be split for both Platinum and Lutino

  • Platinum cocks cannot be split for Lutino

  • Lutino cocks cannot be split for Platinum

  • As genes that share the same chromosomal location can't combine on the one chromosome, it would not be possible to breed a Platinum-Lutino (or Lutino-Platinum)

An explanation for this relationship between Platinums and Lutinos might simply be that the gene that mutated to ''turn off'' the production of dark pigments to create the Lutino effect may have mutated again in a slightly different way, only partially turning off dark pigment production, and thus creating the Platinum effect. If so, this could explain the relationship and genetic interaction that is occurring with these birds.

Platinos are not a new mutation, but a colour effect produced when Platinum and Lutino genes interact. "PLATINOS" have, to my direct knowledge, been around since the 1980s, but more likely they would predate that time by about ten years if we assume the early Platinums were bred with Lutinos. As a point of interest, in the 1980's Platinos were recognised by some breeders as being ''different'' and were sometimes referred to as ''dirty whites''.

An issue still to be considered is what to call these birds. (I think we can rule out ''dirty whites''!) Suggestions have included "Platinum split Lutino", "Lutino-Platinums", and "Double factor and Single factor Platinums", the latter being a term I used in my original article.

Let us examine these three terms separately.

  1. By calling the Platino a Platinum split for Lutino, it is suggestive that it is a full Platinum, carrying the Platinum gene on each of its two sex determining chromosomes. It would then seem a logical conclusion from that description to assume that any offspring would have to inherit a Platinum gene. As this is not the case and the progeny of such a bird will inherit either the Platinum or the Lutino gene, calling it a Platinum (albeit split for Lutino) is misleading.

  2. Whilst the term "Lutino-Platinum" (or vice versa) may give an impression of what the visual characteristics of a Platino are like, it is also misleading, as it suggests the bird is genetically a full Lutino as well as a full Platinum.

  3. "Double" and "Single" factor Platinums was a term used by myself in my original article to put a descriptive label on these bird and to convey the idea that whilst full-coloured male Platinums carried two Platinum genes (double factor) , intermediate coloured males (Platinos) only carried one (single factor). This was never a term that I was particularly comfortable with in terms of its genetic correctness, but it sufficed at the time to get the idea across. Another problem I have with using the term "Single factor Platinum" is that it bears no reference to the fact that the bird also carries Lutino. I suppose you could say single factor Platinum split Lutino. But just as logical would be "single factor Lutino split for Platinum"?

My suggestion for putting a label on this "double split" until such time as all naming options can be carefully considered, is to refer to it as a "PLATINO". If you think about it, the word Platino does symbolise both what this bird is genetically, i.e. half Platinum and half Lutino, as well as what it is colour-wise, which is somewhere between a Platinum and a Lutino.

Mike Anderson © Gumdale Aviaries

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