Sexual selection and the perception of colour

鸟类和人类一样，在社会交往中决定与谁交配、合作和战斗时，会对其他个体展示的颜色和图案做出反应。过去二十年的研究极大地促进了我们对这些颜色和图案信号的理解，我们现在有充分的证据表明，鸟类表现出的颜色信号的变化会影响它们一生的繁殖成功率，因为这些信号可以揭示它们的健康、状况、动机、信号者的经验这些信息被实际的和潜在的配偶用来决定与谁交配以及在亲代照顾下给予配偶多少帮助。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廉价的反射光谱法、图像分析以及用于数据管理、色彩建模和统计分析的计算机程序的发展。不太为人所知的是，感知能力的局限性会影响鸟类的感知和反应。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，但我们对它们区分颜色的能力知之甚少，尤其是当这些颜色只有细微的不同时。我们也不知道区分不同颜色的能力如何影响信号中使用的颜色模式的进化。这项研究计划通过实验室和实地研究来解决这两个问题，研究对象是一组精心挑选的物种，这些物种表现出不同的颜色，生活在不同的环境中，有各种各样的交配系统，并且在分类上多样化。我们选择了其中的几个物种进行研究，因为我们已经研究了它们的视网膜生理学，所以我们可以准确地预测它们的眼睛对光谱的哪一部分最敏感，因此它们的视觉过程可以用数学模型来模拟。这些视觉模型对颜色歧视做出了预测，我们将用行为实验对其进行测试。利用脑成像技术，我们还将绘制出对不同颜色的反应强度，作为对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进化和颜色偏好的机制。我们知道鸟类会比其他颜色更频繁地显示某些颜色，我们的研究将确定这些颜色的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.