Hamilton W D, Brown S P
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
Proc Biol Sci. 2001 Jul 22;268(1475):1489-93. doi: 10.1098/rspb.2001.1672.
Many species of deciduous trees display striking colour changes in autumn. Here, we present a functional hypothesis: bright autumn coloration serves as an honest signal of defensive commitment against autumn colonizing insect pests. According to this hypothesis, individuals within a signalling species show variation in the expression of autumn coloration, with defensively committed trees producing a more intense display. Insects are expected to be averse to the brightest tree individuals and, hence, preferentially colonize the least defensive hosts. We predicted that tree species suffering greater insect damage would, on average, invest more in autumn-colour signalling than less troubled species. Here, we show that autumn coloration is stronger in species facing a high diversity of damaging specialist aphids. Aphids are likely to be an important group of signal receivers because they are choosy, damaging and use colour cues in host selection. In the light of further aspects of insect and tree biology, these results support the notion that bright autumn colours are expensive handicap signals revealing the defensive commitment of individual trees to autumn colonizing insect pests.
许多落叶树种在秋季会呈现出显著的颜色变化。在此，我们提出一个功能性假说：鲜艳的秋色是对抵御秋季入侵害虫的防御投入的一种诚实信号。根据这一假说，信号传递物种中的个体在秋色表达上存在差异，防御投入高的树木会呈现出更浓烈的色彩。预计昆虫会避开颜色最鲜艳的树木个体，因此会优先选择防御能力最弱的宿主进行栖息。我们预测，平均而言，遭受昆虫损害更严重的树种会比受扰较少的树种在秋色信号传递上投入更多。在此，我们表明，在面临多种具有破坏性的专食性蚜虫的树种中，秋色更为浓烈。蚜虫很可能是重要的信号接收者群体，因为它们挑剔、具有破坏性且在宿主选择中会利用颜色线索。结合昆虫和树木生物学的其他方面来看，这些结果支持了这样一种观点，即鲜艳的秋色是代价高昂的不利条件信号，揭示了个体树木对秋季入侵害虫的防御投入。
