Further characterization of Lhr gene, which rescues the lethal hybrid of D. melanogaster and D. simulans, was made using several mutants of D. melanogaster. It was known that hybrids carrying the Y chromosome of D. simulans are lethal without exception, that is, hybrids carrying X chromosome of D. simulans are all viable except a female hybrid of female simulans and male melanogaster. Lhr rescues all the lethal hybrids carrying simulans Y (=hybrids without carrying simulans X). Brief discussion on the character of hybrid lethality between the two species and how the Lhr works are presented.
The Genetics Society of Japan