食果鸟对果实颜色的取食选择及其生态意义

Most terrestrial plants are rooted in place and depend on mobile animals as their seed dispersers. Because seed dispersal is important for plants, the criteria that animal dispersers use in choosing fruits should directly affect the reproductive success of plants. Any fruit trait that enhances the likelyhood that an appropriate seed dispersers will consume the fruit should be favored. It is therefore, fruits traits (for example, colour, odor, nutrition etc.) are traditionally been viewed as an adaptation to increase their delectability to animal dispersers. Animal dispersers are very rich, including almost all the vertebrate and invertebrate taxa, but frugivorous birds and bats are globally the most important seed dispersers. Birds have excellent vision system and mainly depend on colour for food searching,some reports suggested that the evolution of fruit colour are mainly from the pressure of avian food selection. However, few studies to date support this hypothesis that fruit colors are adaptive for fostering bird frugivores. We noticed that studies aim to test this hypothesis are mostly come from new world tropics where frugivorous bats are the predominant seed dispersers. Thus it is not surprising to understand that their conclusions are contentious. Tropical Asia has been suggested to be greater importance than other regions to learn the interaction between bird and fruit colour. Because Tropical Asia has globally the most abundant of fruigivorous bird species, and they are also more important seed dispersers in tropical Asia than their counter parts. However, little studies have conducted in this important region. By method of experimental trials and field survey, we planned to start this topic in tropical Xishangbannan. To our knowledge, this proposal is perhaps the first to study the interaction between fruit colour and fruigivorous bird food preference in tropical Asia.

植物通过果实吸引食果动物取食而达到种子散布目的，二者互惠互利。食果动物种类多，但就种子散布功能而言主要有食果鸟和食果蝙蝠两类。为了吸引足够的动物散布种子，果实的特征（如颜色、营养等）常被认为是适应特定动物类群取食选择的结果。鸟类依靠视觉搜寻食物，而颜色是重要的视觉信号。因此果实颜色的进化被认为是来自食果鸟取食选择压力的结果，然而大量来自于亚洲以外的相关研究并不支持该假说。亚洲热带/亚热带拥有全球最多的食果鸟种类，该地区森林的更新和演替也主要依靠食果鸟进行种子散布，这不同于美洲地区主要依靠食果蝙蝠取食和散布种子。因此，热带亚洲被寄望于研究果实颜色等性状与食果鸟取食选择这个传统生态学命题的首选之地。本研究拟在植物果实和食果鸟种类都十分丰富的西双版纳地区，运用控制实验和野外样地调查相结合的研究方法，讨论食果鸟取食选择与颜色等果实特征性状的关系，有望为该争议的解决提供强有力的新证据。

摘要：. 颜色是果实的一个重要特征，自然界果实颜色多样性高，黑色和红色是最常见的果实颜色。食果鸟的取食选择常被认为是黑色和红色形成的主要驱动因子，但仍存争议。我们通过野外样地观察，以及野外捕获的有取食经验的成鸟和人工养大的无经验幼鸟，运用人工果实和自然果实，就这一理论进行相关验证。结果表明，所有的鸟喜欢红色人工果实，较少取食黄色、蓝色、绿色和黑色人工果实。野外有经验成鸟喜好红色和黑色自然果实，人工养大的无野外取食经验的鸟对黑色的喜好超过红色以及其他颜色的果实。所有的鸟类回避已经成熟的绿色自然果实以及同样营养含量的绿色人工果实。食果鸟对果实颜色的选择在种内个体间波动小，选择结果在时间尺度上比较稳定。研究结果支持鸟类的颜色偏好是热带亚洲地区果实颜色，特别是黑色和红色，形成的主要驱动因子。. 果实颜色与果实营养相组合的实验表明，食果鸟均偏好选择高糖果实，而果实糖含量的变化能改变食果鸟的果实颜色偏好。果实颜色是营养的一种指示，当食果鸟喜好的果实颜色搭配低营养时，食果鸟会改变颜色偏好而选择高糖果实。成鸟与幼鸟均偏好高糖果实，但成鸟对高糖果实的偏好性更强。食果鸟对高糖的偏好是先天的，但后天的经验对果实选择也有影响。食果鸟具有较强的学习能力，当供其选择的果实糖含量发生变化后，食果鸟普遍能在较短的时间内改变取食策略。