| ORIGINAL BOOK REVIEW by Dr. Rainer R. Erhardt "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 little volume to teach anyone the secrets of dealing with recessive, sex-linked, and dominant mutations..." ACBM, Vol. 65, No.12 CLICK TO READ THE REST OF THE REVIEW! 112 pages, 15 chapters, glossary & more! |
Copyright 2006 Linda S. Rubin
| Multiple Bird Households by Linda S. Rubin |
| Series by Linda S. Rubin |
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| Sex-linked Redcessive Inheritance: Do Cockatiel Genetics Work the Same as in Humans? Copyright © 2003 LINDA S. RUBIN CF Genetics Consultant/Panel Judge All Rights Reserved www.CockatielsPlusParrots.com Selected Q&A's "From My Mailbox" Q. Do cockatiel genetics work the same way as in humans? A. In cockatiel genetics, sex-linked recessive genes operate in the opposite manner compared to those of mammals, most insects and some fish. For example, males carry the XX set of sex chromosomes and females carry the XY set of sex chromosomes. That is the reason why males can be either homozygous (visual) or heterozygous (split) for a sex-linked trait. Hens may only be homozygous (visual) for a sex-linked trait. This is because hens have only one X sex chromosome and their Y sex chromosome cannot carry color mutations. Unfortunately, genders cannot be readily identifiable in young, newly weaned cockatiel chicks where non-sex-linked colors are involved. Because genes for sex-linked color mutations are inherited on the sex chromosomes, we know in advance what gender the offspring will be, based on the presence or lack of sex-linked mutations in the resulting offspring. Consider, for example, a sex-linked Pearl cock mated to a Normal Grey hen = XP XP X Y ---------------------------- XP X XP Y XP X XP Y sons produced: 50% Normal Grey split to Pearl (XP X) daughters produced: 50% Pearls (XP Y) In other words, the daughters of the Pearl male will show their sire’s mutation. The sons of the Pearl male will not be visual or display the pearl mutation, but instead carry the sex-linked mutation as a “split.” In this example, the sons appear as Normal Greys (but carry the gene for Pearl). When a cockatiel is over four months of age however, it can be observed for any male behaviors such as singing, warbling a series of notes, or the practice of courtship display such as: hopping, strutting, opening the shoulders and bowing while singing, and tapping objects rapidly with the beak. Although many of these behaviors become evident as males mature into adults, these behaviors may be noticed in young juvenile males from time to time. Females are more sedate compared to males and will have a two- syllable call note (e.g. "eek-eek"). As females mature into adulthood they often times become broody and may show interest in nesting activities. See also: Genetics Charts: Sex-linked Recessives |
| SEX-LINKED RECESSIVE INHERITANCE: DO COCKATIEL GENETICS WORK THE SAME AS IN HUMANS? Copyright © 2003Linda S. Rubin All Rights Reserved |
