Flies exploit predictable perspectives and backgrounds to enhance iridescent signal salience and mating success

Communication requires both the encoding of information and its effective transmission, but little is known about display traits that primarily serve to enhance efficacy. Here we examined the visual courtships of Lispe cana, a cursorial fly that lives and mates in heterogeneous foreshores, and tested the prediction that males should seek to enhance signal salience and consequent fitness through the flexible choice of display locations. We show that courting males access the field of view of females by straddling them and holding their wings closed, before moving ahead to present their structurally coloured faces in ritualised dances. Males preferentially present these UV-white signals against darker backgrounds, and the magnitude of contrast predicts female attention, which in turn predict mating success. Our results demonstrate a striking interplay between the physical and attentional manipulation of receivers and reveal novel routes to the enhancement of signal efficacy in noisy environments.通讯行为兼具信息编码与有效传递两大核心环节，但目前学界对以提升信号效能为首要功能的展示性状仍知之甚少。本研究针对栖息并繁衍于异质潮间带的猎食性蝇类Lispe cana的视觉求偶行为展开探究，并检验了如下预测：雄性可通过灵活选择展示位点，提升信号显著性，进而增强自身适合度。研究发现，求偶雄性会通过跨骑雌性并收拢翅膀，占据雌性的视野范围，随后向前移动，以仪式化舞蹈的姿态展示自身带有结构色的头部区域。雄性优先选择深色背景来呈现这些紫外白色（UV-white）信号，信号与背景的对比度强度可预测雌性的注意力水平，而雌性注意力又能进一步预判交配成功率。本研究结果揭示了接收者所受物理操控与注意力操控之间的精妙相互作用，并为嘈杂环境下提升信号效能找到了全新路径。