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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.
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 |
on the remaining "X" chromosome. Or, if you wish, you may leave it blank as shown in the
parenthesis).
Why does only a single quantity (i.e., one "L" on only one "X" chromosome) indicate a bird that is
split? Because the vacant, remaining "X" chromosome works to cover up the other "X" chromosome
carrying the "L", or gene for Lutino.
Does it matter if we write XL X, or X XL ? No. As long as the "L" or gene for Lutino (or any sex-linked
mutation) appears on one of the "X" sex chromosomes of the pair, it will indicate to you that the male
is carrying the gene. Therefore:
XL X (or XL XN)
reads "Normal Grey split Lutino male" as does:
X XL (or XN XL)
that also reads: "Normal Grey split Lutino male."
The order in which the mutation appears (e.g., whether the "L" is carried by the first or the second "X"
sex chromosome) does not matter.
Next, how would we write a double split male, or a male that carries not one, but two sex-linked
colors? For example, a Normal Grey male split to Lutino and Pearl? We could write:
XL XP = "Normal Grey split Lutino AND Pearl male"
or
XP XL = "Normal Grey split Pearl AND Lutino male"
Again, the order really does not matter, although even if we write XP XL, we might be inclined to say
aloud: "Normal Grey split Lutino AND Pearl male," just because it sounds better, compared to:
"Normal Grey split Pearl AND Lutino male."
Consider this as an example. We are more accustomed to saying "Lutino-Pearl," rather than
"Pearl-Lutino." We also use this order sequence, not only when referring to cockatiel show
classifications, but also in the pet trade, e.g., when referring to splits: i.e., "split to Lutino-Pearl," or
"split to Lutino and Pearl." However in the final analysis, the order in which we either speak or write
parenthesis).
Why does only a single quantity (i.e., one "L" on only one "X" chromosome) indicate a bird that is
split? Because the vacant, remaining "X" chromosome works to cover up the other "X" chromosome
carrying the "L", or gene for Lutino.
Does it matter if we write XL X, or X XL ? No. As long as the "L" or gene for Lutino (or any sex-linked
mutation) appears on one of the "X" sex chromosomes of the pair, it will indicate to you that the male
is carrying the gene. Therefore:
XL X (or XL XN)
reads "Normal Grey split Lutino male" as does:
X XL (or XN XL)
that also reads: "Normal Grey split Lutino male."
The order in which the mutation appears (e.g., whether the "L" is carried by the first or the second "X"
sex chromosome) does not matter.
Next, how would we write a double split male, or a male that carries not one, but two sex-linked
colors? For example, a Normal Grey male split to Lutino and Pearl? We could write:
XL XP = "Normal Grey split Lutino AND Pearl male"
or
XP XL = "Normal Grey split Pearl AND Lutino male"
Again, the order really does not matter, although even if we write XP XL, we might be inclined to say
aloud: "Normal Grey split Lutino AND Pearl male," just because it sounds better, compared to:
"Normal Grey split Pearl AND Lutino male."
Consider this as an example. We are more accustomed to saying "Lutino-Pearl," rather than
"Pearl-Lutino." We also use this order sequence, not only when referring to cockatiel show
classifications, but also in the pet trade, e.g., when referring to splits: i.e., "split to Lutino-Pearl," or
"split to Lutino and Pearl." However in the final analysis, the order in which we either speak or write
such mutation does not have any effecct upon the actual results of the offspring, as diagrammed.
Now, what if we want to chart a Normal Grey male split to Lutino-Pearl? We could write:
XLP XN = "Normal Grey split Lutino-Pearl male"
or
XN XLP = "Normal Grey split Lutino-Pearl male"
Again, the order of which "X" chromosome to assign the "LP" or Lution-Pearl gene does not matter, just so long as one "X" chromosome does carry the "LP."
However, did you notice the difference bwetten writing XL XP "Normal Grey split to Lutino AND Pearl male" and for example:
XLP X (or XLP XN)
that reads, "Normal Grey split to Lutino-Pearl male," which uses the hyphen?
This difference will affect future graphs and charting of offspring. Although we don't fully understand the difference just yet, it will be made clear later on, so at present, let's
just be aware that a difference does exist.
One helpful method to note the difference is by the following: when sex-linked notation (e.g., "LP") is carried together on one "X" sex chromosome only:
XLP X (or XLP XN)
they hyphen is used (e.g., Lutino-Pearl). However, when the genes are carried separately on the "X" chromosomes, XL XP, they are inherited separately which we
recognize by stating, "Normal Grey split Lutino AND Pearl.
This will become more important to us when we eventually examine cross-mutations and the phenomenons known as crossover, and reverse cross-over in chapters
seven and eight.
We are now ready to look at some further examples of sex-linked notation: ... to learn more, order here
Now, what if we want to chart a Normal Grey male split to Lutino-Pearl? We could write:
XLP XN = "Normal Grey split Lutino-Pearl male"
or
XN XLP = "Normal Grey split Lutino-Pearl male"
Again, the order of which "X" chromosome to assign the "LP" or Lution-Pearl gene does not matter, just so long as one "X" chromosome does carry the "LP."
However, did you notice the difference bwetten writing XL XP "Normal Grey split to Lutino AND Pearl male" and for example:
XLP X (or XLP XN)
that reads, "Normal Grey split to Lutino-Pearl male," which uses the hyphen?
This difference will affect future graphs and charting of offspring. Although we don't fully understand the difference just yet, it will be made clear later on, so at present, let's
just be aware that a difference does exist.
One helpful method to note the difference is by the following: when sex-linked notation (e.g., "LP") is carried together on one "X" sex chromosome only:
XLP X (or XLP XN)
they hyphen is used (e.g., Lutino-Pearl). However, when the genes are carried separately on the "X" chromosomes, XL XP, they are inherited separately which we
recognize by stating, "Normal Grey split Lutino AND Pearl.
This will become more important to us when we eventually examine cross-mutations and the phenomenons known as crossover, and reverse cross-over in chapters
seven and eight.
We are now ready to look at some further examples of sex-linked notation: ... to learn more, order here
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| Premiere Book Review by Dr. Rainer R. Erhart |
