Behavior Genetics

, Volume 30, Issue 4, pp 263-275

A Newly Uncovered Phenotype Associated with the fruitless Gene of Drosophila melanogaster: Aggression-like Head Interactions Between Mutant Males

  • Gyunghee LeeAffiliated withDepartment of Biology, Brandeis University
  • , Jeffrey C. HallAffiliated withDepartment of Biology, Brandeis University

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Male sexual behavior is regulated by the sex-determination hierarchy (SDH) in Drosophila melanogaster. The fruitless (fru) gene, one of the regulatory factors functioning downstream of other SDH factors, plays a prominent role in male sexual behavior. Here we demonstrate that fru mutations cause a previously unappreciated behavioral anomaly: high levels of head-to-head interactions between mutant males. These apparent confrontations between males are exhibited by all of the homozygous-viable fru mutants (expressing the effects of a given allele, among the four tested). Mutant dissatisfaction (dsf) males also exhibit this behavior at higher-than-normal levels, but it was barely displayed by doublesex or intersex mutants. For fru, a social component is involved in the head-interaction phenotype, while increasing age is a modifying factor for the behavior of dsf males. We suggest that head-to-head interactions, especially those performed by fru males, are instances of putative aggression analogous to those exhibited by wild-type males and that head interactions are, to an extent, operationally separable from courtship behavior.

Intermale interactions aggression sexual behavior fruitless, dissatisfaction, doublesex, and intersex mutants