The genetic architecture of the male courtship sequence in Drosophila melanogaster

Abstract

Biometrical genetic analysis of the elements of the male courtship sequence in D. melanogaster using diallel and Cavalli cross-breeding designs, revealed that the genetic architecture of the overall level of courtship was characterised by low additivity, sex-linkage and directional dominance for higher levels of courtship. Similar genetic architectures were found for the latter elements of the courtship sequence, with directional dominance for increased amounts of wing vibration, licking, attempted copulation and copulation itself. There was no evidence of sex-linkage for these characters but there was also evidence of some i-type epistatic variation for the wing vibration component of the courtship sequence. The first element of the courtship sequence, orientation, showed a different pattern of inheritance, with again low additive genetic variation but directional dominance for low levels of orientation. These fitness type genetic architectures suggest that the individual elements of the courtship sequence have had a recent history of directional selection favouring a shorter phase of orientation and higher expression of the other courtship elements. This may imply that, though orientation will occur in the initial stages of the courtship process, selection favours males that proceed to the later, more important elements of the courtship sequence fastest. © 1984 The Genetical Society of Great Britain.