Sexual selection and the perception of colour

鸟类和人类一样，在进行交配、合作和战斗的社交活动中做出决定时，会对其他个体显示的颜色和图案做出反应。过去二十年的研究对我们理解这些颜色和图案信号做出了巨大贡献，现在我们有很好的证据表明，鸟类显示的颜色信号的变化会影响它们一生的繁殖成功，因为这些信号可以揭示信号者的健康、状况、动机和经验，实际和潜在的配偶在决定与谁交配以及在父母的照顾下给予配偶多少帮助时，这些信息被利用。研究人员还开发了测量这些信号的复杂方法，这在一定程度上要归功于相对便宜的反射光谱、图像分析以及用于数据管理、颜色建模和统计分析的计算机程序的开发。不太为人所知的是感知能力的极限，这些能力确切地影响着鸟类的感知和反应。例如，我们知道鸟类可以看到我们能看到的所有颜色，加上我们在光谱的紫外线部分看不到的颜色，但我们对它们辨别颜色的能力知之甚少，特别是当这些颜色只有细微差别的时候。我们也不知道这种区分不同颜色的能力如何影响信号中使用的颜色模式的演变。这项研究建议通过对精心挑选的一组物种进行实验室和实地研究来解决这两个问题，这些物种显示出不同的颜色，生活在不同的环境中，具有不同的交配系统，并且在分类上也不同。我们选择了这些物种中的几个进行研究，因为我们已经研究了它们的视网膜生理学，这样我们就可以准确地预测它们的眼睛对光谱的哪个部分最敏感，因此可以用数学模型来模拟它们的视觉过程。这些视觉模型做出了关于颜色辨别的预测，我们将用行为实验进行测试。利用大脑成像技术，我们还将绘制出对不同颜色的反应强度图，作为颜色偏好的衡量标准。这项研究的结果将有助于确定鸟类颜色和颜色偏好进化的潜在机制。我们知道鸟类比其他鸟类更频繁地表现出某些颜色，我们的研究将确定这种颜色范围是否由它们视觉系统的限制决定。我们的发现将对包括人类在内的其他动物的颜色和图案偏好的进化产生广泛的影响。

Birds, like humans, respond to both colours and patterns displayed by other individuals when making decisions during social interactions about who to mate, cooperate, and fight with. Research over the past two decades has contributed immensely to our understanding of those colour and pattern signals, and we now have good evidence that variation in colour signals displayed by birds influences their lifetime reproductive success because those signals can reveal the health, condition, motivation, and experience of the signaller and that information is used by actual and potential mates when deciding on who to mate with and how much assistance to give that mate with parental care. Researchers have also developed sophisticated ways of measuring those signals, thanks in part to the development of relatively inexpensive reflectance spectrometry, image analysis, and computer programs for data management, colour modelling and statistical analysis. What is less well known are the limits of perceptual abilities that influence exactly what birds can perceive and respond to. We know, for example, that birds can see all the colours that we can see plus colure we cannot see in the ultraviolet part of the spectrum, but we know relatively little about their abilities to discriminate between colours, especially when those colours are only subtly different. Nor do we know how that ability to discriminate among different colours influences the evolution of colour patterns used in signalling. This research proposal addresses both of those problems with lab and field studies on a carefully selected group of species that display different colours, live in different environments, have a variety of mating systems, and are taxonomically diverse. We have chosen several of these species for study because their retinal physiology has been studied so we can predict with some accuracy what parts of the spectrum their eyes are most sensitive to, and as a result their visual processes can be modelled mathematically. Those visual models make predictions about colour discrimination that we will test with behavioural experiments. Using brain imaging technologies we will also map the intensity of responses to different colours as a measure of colour preferences. The results of this research will help define the mechanisms underlying the evolution of colours and colour preferences in birds. We know that some colours are displayed more often than others by birds, and our research will determine whether that range of colours is determined by the constraints on their visual system. Our findings will have broad ranging implications for the evolution of colour and pattern preferences in other animals, including humans.