Abstract In the context of mate choice, males may vary continuously in their expression of assessment signals, typically reflecting information about variation in mate quality. Similarly, females may exhibit variation in mate preference, which could be due to differences in how individual females perceive signals. The extent to which perception varies across individuals, however, and whether differences in sensory physiology underlie perceptual differences is poorly understood. Carotenoid pigments create the orange-red coloration of many assessment signals, and they also play a role in color discrimination in many vertebrates via their presence in retinal oil droplets. Here, we link variation in oil droplet carotenoid concentration with the ability of female zebra finches ( Taeniopygia guttata ) to discriminate an orange-red color continuum that parallels variation in male beak color, a mate assessment signal. We have shown previously that zebra finch females perceive this color range categorically, meaning they label color stimuli from this continuum as belonging to two categories and exhibit better discrimination between colors from different categories as compared with equally different colors from within a category. We quantified behavioral color discrimination and R-type (red) cone oil droplet spectral absorption, a proxy for carotenoid concentration. Oil droplet absorption was strongly predictive of variation in behavioral color discrimination ability. In particular, higher carotenoid concentration in oil droplets correlated with increased discrimination of colors from different sides of the previously identified category boundary. These data show that differences in the sensory periphery can correlate with individual variation in perception of a signal-relevant color range. Significance statement Signal receivers vary in their preferences for signaling traits, but whether this is due to variation in how different receivers perceive signals is not well-understood. We show that variation between individual zebra finch females in perception of an orange-red continuum range correlates with the carotenoid concentration of retinal oil droplets. These data provide the first direct evidence that individual variation in oil droplet carotenoid concentration can lead to variation in color discrimination ability. Linking variation in signal-relevant color discrimination ability with variation in retinal physiology suggests a potential mechanism contributing to individual variation in signal assessment.

中文翻译：

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含类胡萝卜素的视网膜油滴的变化与类胡萝卜素着色感知的变化相关

摘要 在配偶选择的背景下，雄性在评估信号的表达上可能会不断变化，通常反映有关配偶质量变化的信息。同样，雌性可能表现出配偶偏好的变化，这可能是由于个体雌性感知信号的方式不同。然而，知觉因人而异的程度，以及感觉生理学的差异是否是知觉差异的基础，我们知之甚少。类胡萝卜素色素产生许多评估信号的橙红色，并且它们还通过它们在视网膜油滴中的存在在许多脊椎动物的颜色辨别中发挥作用。这里，我们将油滴类胡萝卜素浓度的变化与雌性斑胸草雀 (Taeniopygia guttata) 区分橙红色连续体的能力联系起来，该连续体与雄性喙颜色的变化相似，这是一种配偶评估信号。我们之前已经表明，斑胸草雀雌性会分类地感知这个颜色范围，这意味着它们将来自这个连续统的颜色刺激标记为属于两个类别，并且与来自同一类别内的相同不同颜色相比，来自不同类别的颜色之间表现出更好的区分。我们量化了行为颜色歧视和 R 型（红色）锥油滴光谱吸收，这是类胡萝卜素浓度的代表。油滴吸收强烈预测行为颜色辨别能力的变化。特别是，油滴中较高的类胡萝卜素浓度与先前确定的类别边界不同侧的颜色区分度增加相关。这些数据表明，感觉外围的差异可能与个体对信号相关颜色范围感知的差异相关。重要性声明信号接收者对信号特征的偏好各不相同，但这是否是由于不同接收者感知信号的方式不同尚不清楚。我们表明，个体斑胸草雀雌性对橙红色连续谱范围的感知的差异与视网膜油滴的类胡萝卜素浓度相关。这些数据提供了第一个直接证据，即油滴类胡萝卜素浓度的个体差异可导致颜色辨别能力的差异。