Data from: Visual effects in great bowerbird sexual displays and their implications for signal design

It is often assumed that the primary purpose of a male's sexual display is to provide information about quality, or to strongly stimulate prospective mates, but other functions of courtship displays have been relatively neglected. Male great bowerbirds (Ptilonorhynchus nuchalis) construct bowers that exploit the female's predictable field of view (FOV) during courtship displays by creating forced perspective illusions, and the quality of illusion is a good predictor of mating success. Here, we present and discuss two additional components of male courtship displays that use the female's predetermined viewpoint: (i) the rapid and diverse flashing of coloured objects within her FOV and (ii) chromatic adaptation of the female's eyes that alters her perception of the colour of the displayed objects. Neither is directly related to mating success, but both are likely to increase signal efficacy, and may also be associated with attracting and holding the female's attention. Signal efficacy is constrained by trade-offs between the signal components; there are both positive and negative interactions within multicomponent signals. Important signal components may have a threshold effect on fitness rather than the often assumed linear relationship.

长期以来学界普遍假设，雄性性展示的核心功能是传递自身品质信息，或是强力刺激潜在配偶；然而求偶展示的其他功能却相对未受重视。雄性大亭鸟（*Ptilonorhynchus nuchalis*）会建造求偶亭，通过构建强制透视错觉来利用雌性在求偶展示过程中可预判的视野（FOV），而该错觉的质量可有效预测其交配成功率。本文介绍并探讨了雄性求偶展示中另外两项利用雌性预设视野的组成部分：其一为在雌性视野（FOV）范围内快速且多样地闪烁彩色物体；其二为通过调整雌性眼部的色适应状态，改变其对展示物体色彩的感知。二者均未直接与交配成功率相关，但均有望提升信号效能，且可能有助于吸引并维持雌性的注意力。信号效能会受到信号组分间权衡关系的制约；多组分信号内部同时存在正向与负向的交互作用。关键信号组分对适合度的影响可能存在阈值效应，而非学界通常假设的线性相关关系。