Reproductive advantage of the winners of male-male competition in Drosophila prolongata

• Published in: Behavioural processes Vol. 206; p. 104831
• Main Authors: Amino, Kai, Matsuo, Takashi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2023
• Subjects: Animals; Courtship; Deep-learning-based automated behaviour analysis system; Drosophila; Female; Male; Mating system; Reproduction; Resource defence; Sex Characteristics; Sexual Behavior, Animal; Sexual dimorphism; Mating system; Courtship; Resource defence; Sexual dimorphism; Deep-learning-based automated behaviour analysis system
• ISSN: 0376-6357; 1872-8308
• DOI: 10.1016/j.beproc.2023.104831

In the resource-defence mating system, where males compete for limited resources to acquire females, male traits associated with fighting ability are selected, leading to the evolution of sexual dimorphism. However, the evolution of sexual dimorphism is also driven by other mechanisms, such as female selection. Therefore, to elucidate the evolutionary mechanisms of male traits, it is necessary to clarify their contribution to fitness through male-male competition. In this regard, it is surprising that numerous studies on sexually dimorphic species have assumed the resource-defence mating system without directly examining the relationship between resource-defending behaviour and mating success. In a sexually dimorphic fruit fly, Drosophila prolongata, the presence of the resource-defence mating system has been suggested, but technical difficulties had prevented spatial quantification of the resource-defending behaviour. In this study, by using an automated behaviour analysis tool previously developed, we located the occurrence of male-male competition and courtship to investigate their relationship in D. prolongata, considering the position of food resources. We found that the male-male competition led to the exclusive occupation of resources, increasing the courtship opportunities of the resource holders. These results illustrate the importance of resource-defending for reproductive success in D. prolongata. •The contribution of male-male competition to increasing courtship opportunity was tested.•Deep-learning-based automated behaviour analysis was used for this purpose.•Male-male competition was effective to expel the rival from resources.•Males formed a dominant/subordinate hierarchy over the exclusive use of resources.•The exclusive use of resources increased the courtship opportunities of males.