white canary Genetics

WELCOME to White-Canary-Genetics---a-review

The Dominant White Mutation

and its supposed lethality

 

INTRODUCTION

Every blog, every forum and practially every breeding manual dealing with the dominant-white mutation insists that double-factored 'dominant-white' birds do NOT EXIST. The belief is that crossing of dominant-white with dominant-white will result, on average, in a 25% reduction in yield because the double-dose (homozygous) allelic configuration is lethal and leads to dead-in-shell youngsters. The usual outcome diagram, which ASSUMES that each parent is single-dose (heterozygous) and carrying yellow, looks  like this -

                        [DOMINANT-WHITE / yellow]        X      [DOMINANT-WHITE / yellow]

                                                                 OUTCOME

                25 %   [DOMINANT-WHITE /DOMINANT-WHITE]         non-viable, dead-in-shell

                50 %   [DOMINANT-WHITE / yellow]                            visually dominant-white

                25 %   [yellow / yellow]                                                           visually yellow

 

No EVIDENCE whatsoever has been put forward to support this notion, but there is one notable exception to its unquestioned general acceptance and that comes from the eminent Geoff Walker in his book  'Colour, Type and Song Canaries'  where he says - "one is left to conject whether there is any truth in the statement or whether it is another example of the folklore which persists throughout the Fancy and which has no scientific basis" .

Hopefully the EVIDENCE provided on this website will contribute something to nailing that folklore for once and for all.

 

METHOD

A two-season approach was planned.

The first season was designed to increase the stock of possibly double-factored birds by crossing dominant-white with dominant-white. Assuming the folklore to be wrong, then at least some double-factors could be expected.  Twelve birds emerged, but how many were double-factored ? (by the way, there were no dead-in-shell birds nor was there any sign of unviability. All fledged successfully).

The second season called for crosses between the twelve white progeny from the first season (some possibly double-factored) with plain yellows, and the number of consecutive white chicks produced by each white bird was to be counted. Any white parent of a yellow chick was to be eliminated immediately from further consideration because it was obviously single-factored. Nine were so eliminated, and the remaining three, between them, parented six, eight, and eleven chicks consecutively. The formal probability of each parent being double-factored was then calculated.

PROBABILITY

Before calculating the above probability, consider the tossing of a coin, followed by the question 'how many heads in a row do we need before we say - "this coin must be double-headed" ' ?

Listed below are numbers of successive tosses made with a particular coin yielding heads only..... set against the increasing probability of the same coin being double-headed. It will be seen that by formally measuring probability we can arrive at an increasingly confidant answer to the above question, even an answer approaching virtual certainty

Number of  successive 'heads' 
tossed with a particular coin  
%  Probability of same coin 
being double-headed
  
1 {1 - (1/2)} x 100  =   50    %
2 {1 - (1/2 x 1/2)} x 100  =   75    %
3 {1 - (1/2 x 1/2 x 1/2)} x 100  =   87.5 %

If the white test birds were single-factored, and mated to yellows (which are assumed to be double-factored) the outcome would be, on average, 50 % visually white and 50 % visually yellow

                 [DOMINANT-WHITE / yellow]     X     [yellow / yellow]

                                                          outcome

           2 [DOMINANT-WHITE / yellow]       plus        2 [yellow / yellow]

When the headings on the list above are re-labelled as below, and when the second season results are inserted we have :-

Number of  successive 
white youngsters from 
a particular white parent

% Probability of the same 
parent being double-factored
6 {1 - (1/26)} x 100         =  99.44 %
8 {1 - (1/28)} x 100         =  99.61 %
11 {1 -  (1/211)} x 100         =  99.95 %

 

CONCLUSION

These results make it certain that the double-factored dominant-white exists, and that any breeder who has self-crossed dominant-whites has, unknown to himself, probably produced some of these double-factored birds.,
 


 

Contact details for White-Canary-Genetics---a-review

Contact:Donal Hayes
Address:6 Dollymount Rise
Clontarf
Dublin
None
Ireland
Telephone:01 8336680
Email:donalhayes@mail.com
Web page:www.whitecanarygenetics.eu

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