Courtship Behaviour in the Melanogaster Species Sub-Group of Drosophila

Abstract

Descriptions of courtship behaviour are given for seven members of the melanogaster species sub-group: Drosophila melanogaster, simulans, mauritiana, yakuba, teissieri, erecta and orena. A male wing behaviour not previously reported, wing extension, was observed in either 1- or 2-wing variants in all species except melanogaster and simulans. Male wing rowing, previously reported in mauritiana and teissiri, was seen in 1- or 2-wing variants in all species except melanogaster and orena. D. teissieri showed the most extreme form of wing rowing, and yakuba the widest variety of angles of wing vibration. Tapping by the male was observed in all species except simulans and mauritiana, but not always at the onset of courtship and not in every courtship. Extrusion in virgin females was observed in melanogaster and erecta, and abdomen extension in female simulans, yakuba, teissieri and orena. Female wing behaviours were observed in all species except simulans. Wing extension and wing rowing are distinct from vibration and scissoring (behaviours they strongly resemble). There is strong a behavioural connection between these pairs of behaviours, in that wing extension often leads to vibration, wing rowing to scissoring, and vice versa. A mechanical function for licking is proposed, following observation of long duration licking in yakuba. The function of licking is thought to be elevation of the female's abdomen, preparatory to copulation. The relationship between the seven species based on their courtship behaviours was examined using principal coordinates analysis. This suggests that the two cosmopolitan species, simulans and melanogaster, differ most widely in their courtship behaviour, with mauritiana being the most similar to simulans. This finding is assessed in relation to the ecology of the seven species, the role of courtship behaviour in speciation, and the reliability of inferences from behaviour in phylogenetic analyses. Descriptions of courtship behaviour are given for seven members of the melanogaster species sub-group: Drosophila melanogaster, simulans, mauritiana, yakuba, teissieri, erecta and orena. A male wing behaviour not previously reported, wing extension, was observed in either 1- or 2-wing variants in all species except melanogaster and simulans. Male wing rowing, previously reported in mauritiana and teissiri, was seen in 1- or 2-wing variants in all species except melanogaster and orena. D. teissieri showed the most extreme form of wing rowing, and yakuba the widest variety of angles of wing vibration. Tapping by the male was observed in all species except simulans and mauritiana, but not always at the onset of courtship and not in every courtship. Extrusion in virgin females was observed in melanogaster and erecta, and abdomen extension in female simulans, yakuba, teissieri and orena. Female wing behaviours were observed in all species except simulans. Wing extension and wing rowing are distinct from vibration and scissoring (behaviours they strongly resemble). There is strong a behavioural connection between these pairs of behaviours, in that wing extension often leads to vibration, wing rowing to scissoring, and vice versa. A mechanical function for licking is proposed, following observation of long duration licking in yakuba. The function of licking is thought to be elevation of the female's abdomen, preparatory to copulation. The relationship between the seven species based on their courtship behaviours was examined using principal coordinates analysis. This suggests that the two cosmopolitan species, simulans and melanogaster, differ most widely in their courtship behaviour, with mauritiana being the most similar to simulans. This finding is assessed in relation to the ecology of the seven species, the role of courtship behaviour in speciation, and the reliability of inferences from behaviour in phylogenetic analyses.