Does lepidopteran larval crypsis extend into the ultraviolet?
Does lepidopteran larval crypsis extend into the ultraviolet?
复制标题
DOI：
10.1007/s001140050483
复制
发表时间：
1998-04-01
影响因子：
--
通讯作者：
Partridge, JC
中科院分区：
文献类型：
--
作者：
Church, SC;Bennett, ATD;Partridge, JC
隐蔽性和拟态保护性的颜色图案经常被引用为自然选择的一些最精致的例子（例如Fisher 1958； Kettlewell 1973）。然而，我们对保护性颜色的解释和理解在很大程度上没有考虑到捕食者作为选择性代理人的视觉能力。Endler（1978）将一种颜色模式定义为隐色，“如果它类似于捕食者在当时和年龄所感知到的背景的随机样本，并且在猎物最容易受到视觉捕食者攻击的微栖息地中”（我们的斜体）。然而，迄今为止，几乎没有关于隐色的研究考虑到捕食者的视觉系统。相反，他们使用基于人类视觉系统的颜色评估来进行研究（Bennett and Cuthill 1994; Bennett et al. 1994）。鸟类捕食者很可能是昆虫隐密和模仿相似性进化的主要选择力量（Dempster 1984）。然而，现在很清楚的是，大多数鸟类掠食者都拥有与人类截然不同的高度复杂的视觉系统。人类是三色的，拥有三种视锥细胞类型（长波、中波和短波敏感），只能探测到波长范围约为400-700纳米的光。相比之下，大多数鸟类都有四色视（甚至更高维度的色彩空间）的潜力。它们至少具有四种光谱上不同的单锥型（Chen and Goldsmith 1986; Bennett and Cuthill 1994; Bowmaker et al. 1997），这些锥型又与作为截止过滤器的彩色油滴有关（Partridge 1989; Bowmaker et al. 1997）。此外，除了人类可见光谱外，鸟类还能探测到300-400纳米范围内的紫外线（UV）波长（Huth and Burkhardt 1972; Wright 1972; Bennett and Cuthill 1994）。这种紫外线敏感性已经被证明在几个物种的配偶选择决策中具有重要的行为后果（Maier 1993； Bennett等人1996,1997；Andersson和Amundsen 1997； Andersson等人1998；Hunt等人1998），以及在觅食的红隼探测紫外线可见的田鼠气味标记中（Viitala等人1995）。还有一种假设（Bennett和Cuthill 1994）认为鸟类在猎物探测或辨别任务中使用紫外线线索（例如在自然背景下探测隐藏的昆虫）。如果一个“隐蔽的”猎物的光谱反射率和它在紫外线下的背景之间存在差异，那么对于鸟类来说很可能是明显的，但在相同的观察条件下，对于人类观察者来说却不是。因此，先前对鸟类捕食系统中隐色的评估只是部分完成的，因为它们忽略了鸟类可以探测到的光谱的重要部分。显然，对隐色的研究需要根据这一知识进行重新评估。在这项研究中，我们研究了在英国橡树（栎）上常见的食植物鳞翅目幼虫的颜色隐隐是否延伸到紫外线。我们于1997年5月和6月在布里斯托尔附近的橡树林中取样毛虫。从18棵不同的橡树的下枝上获得了晚龄标本。我们记录了橡树叶的上、下表面和六种绿毛虫的活标本的反射光谱。其中冬蛾（夜蛾目）
Cryptic and mimetic protective colour patterns are often cited as some of the most exquisite examples of natural selection in the wild (eg Fisher 1958; Kettlewell 1973). Nevertheless, our interpretation and understanding of protective coloration has proceeded largely without consideration of the visual capabilities of the predators which act as selective agents. Endler (1978) defines a colour pattern as cryptic “if it resembles a random sample of the background perceived by the predators at the time and age, and in the microhabitat where the prey is most vulnerable to visually hunting predators”(our italics). However, virtually no studies of cryptic coloration to date have considered the visual system of the predator. Instead, they have been carried out using assessments of colour based on the visual system of humans (Bennett and Cuthill 1994; Bennett et al. 1994). Avian predators are likely to be a major selective force on the evolution of cryptic and mimetic resemblances of insects (Dempster 1984). Yet it is now clear that the majority of avian predators possess a highly sophisticated visual system which is very different from our own. Humans are trichromatic, possessing three cone types (long-, medium-and short-wave sensitive) and can detect light only in the wavelength range ca. 400–700 nm. In contrast, most birds have the potential for tetrachromacy (or even higher dimensions of colour space). They possess at least four spectrally distinct single cone types (Chen and Goldsmith 1986; Bennett and Cuthill 1994; Bowmaker et al. 1997) which are in turn associated with coloured oil droplets acting as cut-off filters (Partridge 1989; Bowmaker et al. 1997). Furthermore, birds can detect ultraviolet (UV) wavelengths in the range 300–400 nm in addition to the human visible spectrum (Huth and Burkhardt 1972; Wright 1972; reviewed by Bennett and Cuthill 1994). This UV sensitivity has already been shown to have important behavioural consequences in mate choice decisions of several species (Maier 1993; Bennett et al. 1996, 1997; Andersson and Amundsen 1997; Andersson et al. 1998; Hunt et al. 1998) and in the detection of UV-visible vole scent-marks by foraging kestrels (Viitala et al. 1995). It has also been hypothesised (Bennett and Cuthill 1994) that birds use UV cues in prey detection or discrimination tasks (eg detecting a cryptic insect on its natural background). If there is a difference between the spectral reflectance of a “cryptic” prey item and its background in the UV, it is very likely to be apparent to a bird, but not to a human observer under identical viewing conditions. Thus previous assessments of cryptic coloration in systems subject to avian predation are only partially complete in the sense that they ignore a significant portion of the spectrum which can be detected by birds. Clearly investigations into cryptic coloration need to be reappraised in the light of this knowledge.In this study we examined whether colour crypsis extends into the UV in species of phytophagous lepidopteran larvae commonly found on Oak trees (Quercus robur) in the United Kingdom. We sampled caterpillars from oak woodland around Bristol during May and June 1997. Late instar specimens were obtained from the lower branches of 18 different oak trees. We recorded the reflectance spectra from the upper and lower surfaces of the oak leaves and from live specimens of six species of green (to human eyes) caterpillars. The six species were the winter moth (Operophtera