Principles of Genetics and Breeding

3.1.6.2 Recessive lethal genes

• In guppy, Poecilia reticulata, when two Y-chromosomes are combined in a male, homozygotes with respect to genes ma (maculatus), ar (Armatus) and pa (Pauper) turn out to be non-viable.
• Mean while, the males with genotypes Yma Yar, Yma Ypa and Ypa Yar are viable and in addition fertile.
• It appears that a special lethal gene is closely linked with each of the genes located in Y chromosome;
• the lethal genes associated with different genes are non-allelic.