Melin A D, Kline D W, Hickey C M, Fedigan L M
Department of Anthropology, University of Calgary, Canada.
Vision Res. 2013 Jun 28;86:87-96. doi: 10.1016/j.visres.2013.04.013. Epub 2013 May 3.
Efficient detection and selection of reddish fruits against green foliage has long been thought to be a major selective pressure favoring the evolution of primate trichromatic color vision. This has recently been questioned by studies of free-ranging primates that fail to show predicted differences in foraging efficiency between dichromats and trichromats. In the present study, we use a unique approach to evaluate the adaptive significance of trichromacy for fruit detection by undertaking a functional substitution model. The color vision phenotypes of neotropical monkeys are simulated for human observers, who use a touch-sensitive computer interface to search for monkey food items in digital images taken under natural conditions. We find an advantage to trichromatic phenotypes - especially the variant with the most spectrally separated visual pigments - for red, yellow and greenish fruits, but not for dark (purple or black) fruits. These results indicate that trichromat advantage is task-specific, and that shape, size and achromatic contrast variation between ripe and unripe fruits cannot completely mitigate the advantage of color vision. Similarities in fruit foraging performance between primates with different phenotypes in the wild likely reflect the behavioral flexibility of dichromats in overcoming a chromatic disadvantage.
长期以来，人们一直认为在绿色树叶背景下高效地检测和挑选红色果实是推动灵长类动物三色视觉进化的主要选择压力。最近，对野生灵长类动物的研究对此提出了质疑，这些研究未能显示出二色视觉者和三色视觉者在觅食效率上的预期差异。在本研究中，我们采用一种独特的方法，通过建立功能替代模型来评估三色视觉对果实检测的适应性意义。我们为人类观察者模拟了新热带猴的色觉表型，观察者使用触摸感应计算机界面在自然条件下拍摄的数字图像中寻找猴类食物。我们发现，对于红色、黄色和绿色果实，三色视觉表型具有优势，尤其是视觉色素光谱分离度最高的变体，但对于深色（紫色或黑色）果实则没有优势。这些结果表明，三色视觉优势具有任务特异性，并且成熟果实与未成熟果实之间的形状、大小和非彩色对比度变化并不能完全抵消色觉的优势。野生环境中不同表型的灵长类动物在果实觅食表现上的相似性，可能反映了二色视觉者在克服色彩劣势方面的行为灵活性。
