近日，一项新的研究发现，斑马纹可干扰采采蝇和马蝇用来寻找水和食物的光模式。相关论文发表在The Journal of Experimental Biology上。因此，如果你要去非洲旅行，记得带上一件斑马纹的衬衣。
专家表示，该发现是解决为什么在斑马身上会产生这种独特的花纹这个谜题上的一个令人激动的进展。“这是从人们开始讨论这个话题120年以来第一次真正有说服力的证据，”并未参与该项烟酒店饿加州大学行为生态学家Tim Caro说道。
人们对斑马的条纹进行了多年的推测，各种理由都有，比如迷惑捕食者、便于在草丛中伪装、利于同伴在庞大的兽群中找到彼此等等。
但是没有人对这些假说进行实验验证，这项新研究的作者、瑞典兰德大学的进化生物学家Susanne ?kesson说。她对斑马是否容易招虻类昆虫感到很好奇。虻是一类臭名昭著的昆虫，包括采采蝇和马蝇，会传染诸如昏睡症和美洲锥虫病等疾病。早期有关虻蝇对黑色、白色或条纹着陆面的偏好性实验发现，它们更喜欢黑色方块，但是没有解释为什么。
?kesson和她的同事从她们对马蝇的认识开始着手研究。他们此前的研究发现，相比于白马，深颜色的马更容易招虫子，因为深颜色的外皮反射同一方向的光。这种极化的光与蝇类产卵用的水池所反射的光是一样的。而白色外皮则不能反射这种极化光。
为了考证斑马的白色条带是否对虻类的吸引力较低，该研究团队在一个马场设置了一系列的实验。他们测试了纯黑、纯白以及黑白相间方块对虻类的吸引力，也测试了与真马同样大的黑色、棕色、白色或带状外表的塑料马对虻类的吸引力。他们还以各种数量及宽度的灰色方块来测试花纹模式对马蝇偏好性的影响。研究者们用植物油来吸引虻落下，并且在塑料马上涂上无色无味的胶水来粘住落下的虻。
结果发现，条状对虻的吸引力甚至还不如纯黑色的吸引力强。这是因为条状花纹反射多种模式的光，相反，纯黑色则反射这些蝇类喜欢的统一模式的光，作者们说。因此，即使是纯白方块也比条状更有吸引力。该研究结果发表在The Journal of Experimental Biology上。
该团队强调，他们的研究结果需要在生活在自然栖息地的斑马上进一步确认。气味能让颜色更加吸引虻蝇，他们指出，而野外的斑马发出的气味非常强烈，这种气味可能会使觅食的虻类忽视视觉上的不适。
斑马并不会在空旷的平地中遭遇，虻蝇，Caro说。不过kesson指出，斑马和虻蝇都会在水边逗留。
尽管存在这些需要特别说明的问题，这还是一项非常令人激动的工作，Ruxton说。这无疑是有关斑马条纹的最为严密的实验，他说。(生物谷Bioon.com)
doi:10.1242/jeb.065540
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Polarotactic tabanids find striped patterns with brightness and/or polarization modulation least attractive: an advantage of zebra stripes
Ádám Egri, Miklós Blahó, György Kriska, Róbert Farkas, Mónika Gyurkovszky, Susanne Åkesson and Gábor Horváth
The characteristic striped appearance of zebras has provoked much speculation about its function and why the pattern has evolved, but experimental evidence is scarce. Here, we demonstrate that a zebra-striped horse model attracts far fewer horseflies (tabanids) than either homogeneous black, brown, grey or white equivalents. Such biting flies are prevalent across Africa and have considerable fitness impact on potential mammalian hosts. Besides brightness, one of the likely mechanisms underlying this protection is the polarization of reflected light from the host animal. We show that the attractiveness of striped patterns to tabanids is also reduced if only polarization modulations (parallel stripes with alternating orthogonal directions of polarization) occur in horizontal or vertical homogeneous grey surfaces. Tabanids have been shown to respond strongly to linearly polarized light, and we demonstrate here that the light and dark stripes of a zebra’s coat reflect very different polarizations of light in a way that disrupts the attractiveness to tabanids. We show that the attractiveness to tabanids decreases with decreasing stripe width, and that stripes below a certain size are effective in not attracting tabanids. Further, we demonstrate that the stripe widths of zebra coats fall in a range where the striped pattern is most disruptive to tabanids. The striped coat patterns of several other large mammals may also function in reducing exposure to tabanids by similar mechanisms of differential brightness and polarization of reflected light. This work provides an experimentally supported explanation for the underlying mechanism leading to the selective advantage of a black-and-white striped coat pattern.
