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for Breeding, Genetics,
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Copyright © Linda S. Rubin | CockatielsPlusParrots.com
Cockatiel Genetics Made Easy!
  • 112 pages
  • 15 Chapters
  • Chapter quizzes
  • Chapter answers
  • Glossary definitions & more ...
Used with great success by cockatiel breeders
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"Well, there is help on the horizon and anyone
seriously interested in color genetics should take
a look at Linda Rubin's book: COCKATIEL
GENETICS MADE EASY! Though this book is
primarily directed to breeders of cockatiel
mutations, there is enough information in this
volume to teach anyone the secrets of dealing
with recessive, sex-linked, and dominant
mutations.
Click to read rest of review
- Dr. Rainer R. Erhart, American Cage Bird Magazine,
Volume 65, No. 12. p. 37.
Excerpt  From Chapter 6
Charting Sex-linked Mutations
In chapter three, we learned the notation for writing and interpreting sex-linked
mutations. Armed with this information, we are now ready to chart these sex-linked
mutations by working with a slightly modified graph as shown below:

Sire's Chromosome Pair                                           Dam's Chromosome Pair             

Pairing #1: Male Offspring                                         Pairing #3: Female Offspring


Pairing #2: Male Offspring                                          Pairing #4: Female Offspring




We may also use our subscript numbers once again, as a learning aid to the above graph,
merely to demonstrate how the sex chromosomes pair off:



                   
___X1    X2                           X3    X4         

                          X1    X3                           X1    X4

                          X2    X3                           X2    X4



You may also "feel" the familiar technique of the FOIL method we learned in the previous
chapter. However, as we will be charting the sex-linked colors somewhat out of order
(compared to the recessive graph you learned in the previous chapter), the FOIL method will
also differ somewhat in this chapter. Yet, it will be easier for you later on, if you learn to complete
the left (male) side of the diagram, before going on to complete the right (female) side. This will
be expalined as we progress through the chapter.

We will initially demonstrate both the subscript numbers, and the FOIL technique (to check your
work) in this chapter, until with enough practice you no longer need to rely upon them.

In chapter two, we listed seeral assumptions under the "Golden Rules," which we
will prove throughout this chapter. You may refer back to chapter two for additional information as we cover them however, the major points are repeated here for your
convenience.


                                                                                                        I.  NORMAL GREY   X   MUTATION MATINGS

Let's start by charting a Normal Grey cockatiel with the sex-linked Lutino mutation. Remember, now that we are working with sex-linked mutations, it is imperative to
identify the gender of each carrier of a mutation. In other words, we need to know the sex of the parent who is affected by one or more sex-linked mutations.

                                                                                                Example:  
NORMAL GREY COCK   X  LUTINO HEN


                                                                                                                            F      O                       I        L

                                                                         XN          XN                    XL       Y                           X1    X2                     X3    Y4   

                                                                        XN          XL                    XN        Y                          X1    X3                     X1    Y4

                                                                        XN          XL                    XN        Y                           X2   X3                      X2    Y4




The above graph utilizing numbers shown at right will help you to move each "X" and "Y" chromosome to their proper position. You will note how each chromosome is
assigned a number to illustrate where it is to be placed on the completed graph at left.

In addition, the letters of the acronym "FOIL" are positioned on top of the graph with numbers to aid you with checking your work below. Each letter of the acroym (i.e.,  
F. O.
I.  L.
) shown on the graph stands for the first letter representing the position of First, Outer, Inner, and Last.  Also, each quadrant (upper and lower, right and left) is now
identified.

                     
You will note a slight modification in the FOIL method given below, between steps two and three which are now
inversed.  The inversed steps are underlined to show how
they differ from what you've learned in the preceding chapter.
 ... to learn more, order here
FOIL METHOD
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Overview & Book Review                  Table of Contents                    Preface                     Chapter 2                     Chapter 3                    Chapter 6                     Chapter 10                 Order >>
Premiere Book Review
by Dr. Rainer R. Erhart