BIRDS2U
 Publication of this website            20 March 2012                 Modified  30 March; 07 April;12 April; 22 April; 08 May; 20 May; 12 June; 23 June; 27 June; 07 July; 27 July; 26 Aug.; 24 Dec.; 2013: 03 May ; 30 May; 11 July: 24. Aug.; 18 Dec.; 2014: 05 Feb. ; 13 March; 19 April; 24 May; 16 June; 11 Sept.; 26 Sept.; 07 Oct.; 27 Oct.; 15 Jan. 2015; 07 April; 03 May; 16 June; 29 July; 12 Sept.; 04 Nov.; 01 Dec.; 2016: 26 Feb.; 13 April; 19 July; 10 Dec.; 2017: 16 Jan.; 26 Aug.; 8 Sept.; 20 Sept.; 20 Oct.; 30 Oct.; 2018: 21 Jan.; 21 Febr.; 10 July; 14 Aug.; 25 Sept.;
© by Wekrue WebDesign 2018
Home Bird Care & Nutrition Birdblog Bird Diseases Birds2u Database Birds2u TALKATIVE Book Descriptions Birds2u Online-Store Birds for sale Gallery Recommended Links Contact Site Map info

WHAT IS

SEX-LINKED RECESSIVE INHERITANCE IN BIRDS?

Sex-linked genes are located only on the sex-chromosomes. Sex-linked recessive means that the gene for a recessive factor in a bird is located on the sex-chromosome. Females have only one sex-chromosome (X-). Males have two sex-chromosomes (XX). In females, if they have the sex-linked gene, the factor will be visible, as they have only one sex-chromosome to which the sex-linked gene is on. In males, the sex-linked recessive factor will be visible if it is located on both sex-chromosomes. The factor is not visible in males if only one sex-chromosome carries the gene. If a male carries only one gene with the recessive factor, than it is split for the recessive factor. Females never can be split for a sex-linked gene. Here are some mating examples: X = Sex-Chromosome, also called X-Chromosome F = Factor (recessive)
MALE (XF)
F E M A L E
X
F
X
X
X
F
X
X
F
MALE (FF)
F E M A L E
F
X
X
X
F
F
F
F
F
MALE (XF)
F E M A L E
X
F
F
X
F
F
X
F
F
MALE (FF)
F E M A L E
F
F
F
F
F
F
F
F
F
Male: double-factor = visible for the recessive factor Female: without the recessive factor Results: 50 % males, single-factor = split for the recessive factor (XF)               50 % females, single-factor = visible for the recessive factor (F-)
Male: single-factor or split for the recessive factor Female: without the recessive factor Results: 25 % males, without the recessive factor (XX)               25 % males, single-factor = split for the recessive factor (XF)                                     25 % females, single-factor = visible for the recessive factor (F-)               25 % females, without the recessive factor (X-)
Male: double-factor = visible for the recessive factor Female: single-factor = visible for the recessive factor Results: 50 % males, double-factor = visible for the recessive factor (FF)               50 % females, single-factor = visible for the recessive factor (F-)
(X-)
(F-)
(F-)
Male: single-factor or split for the recessive factor Female: single factor = visible for the recessive factor Results: 25 % males, single-factor or split for the recessive factor (XF)               25 % males, double-factor and visible for the recessive factor (FF)                                     25 % females, without the recessive factor (X-)                    25 % females, single-factor = visible for the recessive factor (F-)
(X-)
MALE (XX)
F E M A L E
X
X
F
F
F
X
X
X
X
(F-)
Male: without the recessive factor Female: single factor = visible for the recessive factor Results: 50 % males, single-factor or split for the recessive factor (FX)                                         50 % females, without the recessive factor (X-)                   
Birds2u-Online-Store with a lot of reasonable offers, such as books, magazines, food, cages, equipments and many other products for Your bird! Have a look...>
W. Hagelberg's zoologischer Hand-Atlas              
was published between 1879-1881. The second part (Part B) includes the part AVES. It’s a collection of 285 rare bird illustrations read more>