Principles of Genetics and Breeding

4.2.4.1 Sex-linked inheritance in the Platy- WZ/ZZ system

The black strain ‘Nigra’ is inherited as a dominant sex linked allele. Female possessed the different or contrasting pair of sex chromosomes. Thus, a cross between a ‘Nigra’ female and a lightly pigmented male ‘white” produced ‘Nigra’ sons and ‘white’ daughters which, in an F₂ produced approximately equal frequencies of ‘Nigra’ and ‘white’ individuals of each sex. Allele for ‘Nigra’ as N and that for ‘white’ as W. The inheritance in this system follows criss-cross pattern.

Wo Zn x Zw Zw

Nigra ♀ White ♂

↓

Wo Zw Zn Zw

White ♀ Nigra ♂

↓

Wo Zn : Wo Zw : Zn Zw : Zw Zw

Nigra ♀ White ♀ Nigra ♂ White ♂

Figure 7.1. Sex linked inheritance in platy.