|Unique Avian Solutions
for Breeding, Genetics,
and Companion Parrots
|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
and zoos worldwide
"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 3
Sex-linkage: Mutations & Symbols
Before we set up a graph to chart the color possibilities of future offspring, we must first learn
how to assign the colors and mutations with symbols with which we plan to work. We shall
begin by discussing the sex-linked recessive mutations. Once we have mastered sex-linked
notation, we will then work with the autosomal recessive mutations. You may want to review this
chapter several times to be certain you understand the material, because you will need to know
this information if you wish to learn to chart cockatiel color genetics.
The following symbols illustrate how sex-linked mutations are written. As you may recall from
the preceding chapter, upper case letters are used to denote the sex-linked recessive
mutations, for example:
L stands for Lutino
P stands for Pearl
C stands for Cinnamon
We simply use this notation and position the genes for these colors and patterns symbolically
by placing them on the "X" sex chromosomes. Remember, the "Y" sex chromosome cannot
carry sex-linked mutations!
To graph a Lutino hen, we must first write down her sex chromosomes:
By assigning one "X" and one "Y" chromosome, we know we have a female (XY). Next, we need
to place the sex-linked gene "L" for Lutino on the hen's "X" sex chromosome. She therefore
Now let's try and graph a Lutino male. We know that the male carries two "X" sex chromosomes,
so we write:
We also know from reading chapter two that we need the Lutino in double quantity
in order for the mutation to be visual, therefore we write:
which indicates a visual Lutino male cockatiel.
Conversely, if we want to indicate a bird with no mutation, for example a Normal Grey cockatiel, we have two ways to illustrate such a bird.
The first method is to simply list the sex chromosomes of the bird (thereby indicating its sex) and write nothing beside the "X" sex chromosomes:
X Y = a Normal Grey hen, or
X X = a Normal Grey male
The second option, which I highly recommend when first learning to chart color genetics is to assign the capital letter "N," which stands for Normal Grey, to any
vacant "X" sex chromosome.
Some students in my workshops have felt more comfortable if they are able to assign something to each "X" sex chromosome they work with rather than leaving an
"X" blank. Either method is correct, and if you feel more comfortable with assigning an "N" to indicate Normal Grey - to an otherwise empty "X" chromosome, then
please do. Just remember, this procedure is only permitted when working with the "X" sex chromosomes, not the "Y."
For now, we will continue to assign the capital letter "N" to stand for Normal Grey for several more chapters until you have progressed to the point where we can
comfortably drop it.
Now, what if we want to indicate a male split to one or more sex-linked mutations? Again, let's break it down. Let's suppose we want to consider a Normal Grey male
split to Lutino. First, we must assign the bird his male sex chromosomes: X X.
Next, by referring back to chapter two, we remember that a mutation must be in double quantity for it to be visual however, "A single quantity on only one "X"
chromosome indicates a bird that is SPLIT. Therefore we write:
XL XN (or XL X)
which reads, Normal Grey split Lutino male. Remember we are using the upper case letter "N" here to indicate there is no other mutation continue