Hsiung Bor-Kai, Justyn Nicholas M, Blackledge Todd A, Shawkey Matthew D
Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
Integrated Bioscience Program, The University of Akron, Akron, OH 44325-3908, USA.
J Exp Biol. 2017 Jun 1;220(Pt 11):1975-1983. doi: 10.1242/jeb.156083.
Elucidating the mechanisms of colour production in organisms is important for understanding how selection acts upon a variety of behaviours. Spiders provide many spectacular examples of colours used in courtship, predation, defence and thermoregulation, but are thought to lack many types of pigments common in other animals. Ommochromes, bilins and eumelanin have been identified in spiders, but not carotenoids or melanosomes. Here, we combined optical microscopy, refractive index matching, confocal Raman microspectroscopy and electron microscopy to investigate the basis of several types of colourful patches in spiders. We obtained four major results. First, we show that spiders use carotenoids to produce yellow, suggesting that such colours may be used for condition-dependent courtship signalling. Second, we established the Raman signature spectrum for ommochromes, facilitating the identification of ommochromes in a variety of organisms in the future. Third, we describe a potential new pigmentary-structural colour interaction that is unusual because of the use of long wavelength structural colour in combination with a slightly shorter wavelength pigment in the production of red. Finally, we present the first evidence for the presence of melanosomes in arthropods, using both scanning and transmission electron microscopy, overturning the assumption that melanosomes are a synapomorphy of vertebrates. Our research shows that spiders have a much richer colour production palette than previously thought, and this has implications for colour diversification and function in spiders and other arthropods.
阐明生物体中颜色产生的机制对于理解选择如何作用于各种行为至关重要。蜘蛛提供了许多在求偶、捕食、防御和体温调节中使用颜色的惊人例子，但人们认为蜘蛛缺乏许多其他动物常见的色素类型。在蜘蛛中已鉴定出眼色素、胆色素和真黑素，但未发现类胡萝卜素或黑素小体。在这里，我们结合光学显微镜、折射率匹配、共焦拉曼显微光谱和电子显微镜来研究蜘蛛几种彩色斑块的基础。我们得到了四个主要结果。第一，我们表明蜘蛛利用类胡萝卜素产生黄色，这表明这种颜色可能用于依赖条件的求偶信号传递。第二，我们建立了眼色素的拉曼特征光谱，便于未来在各种生物体中鉴定眼色素。第三，我们描述了一种潜在的新的色素 - 结构色相互作用，这种相互作用不同寻常，因为在产生红色时使用了长波长结构色与稍短波长色素相结合。最后，我们使用扫描电子显微镜和透射电子显微镜首次提供了节肢动物中存在黑素小体的证据，推翻了黑素小体是脊椎动物共近裔性状的假设。我们的研究表明，蜘蛛拥有比以前认为的丰富得多的颜色产生调色板，这对蜘蛛和其他节肢动物的颜色多样化和功能具有重要意义。
