Sex linked lethals in Drosophila

Content
Sex Linked, Sex Influenced and Sex Limited Traits
Sex linked traits 
Sex linkage in Drosophila
Sex linked lethals in Drosophila
Sex linkage in human beings
Sex linkage in poultry
Non-disjunction of sex chromosomes in Drosophila
Sex Influenced Traits (horned character in sheep)
Sex Limited Traits (cock feathering in poultry and baldness in man).

In Drosophila, occasional females regularly produce female and male progeny in 2 : 1 ratio, which means that half of male progeny is missing. In small populations this can be explained on the basis of sampling error. However, in Drosophila, large populations can be handled and therefore the difference becomes rather significant. In such cases, it can be explained to be due to presence of sex linked lethal (recessive) in heterozygous condition in female parent (Fig. 16.7).
 
Pattern of inheritance of sex linked recessive lethal carried by a heterozygous female in Drosophila.
Fig. 16.7. Pattern of inheritance of sex linked recessive lethal carried by a heterozygous female in Drosophila.