White Thomas E, Umbers Kate D L
School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2106, Australia.
School of Science, Western Sydney University, Penrith, New South Wales 2751, Australia.
Proc Biol Sci. 2021 Apr 28;288(1949):20210679. doi: 10.1098/rspb.2021.0679.
The combined use of noxious chemical defences and conspicuous warning colours is a ubiquitous anti-predator strategy. That such signals advertise the presence of defences is inherent to their function, but their predicted potential for quantitative honesty-the positive scaling of signal salience with the strength of protection-is the subject of enduring debate. Here, we systematically synthesized the available evidence to test this prediction using meta-analysis. We found evidence for a positive correlation between warning colour expression and the extent of chemical defences across taxa. Notably, this relationship held at all scales; among individuals, populations and species, though substantial between-study heterogeneity remains unexplained. Consideration of the design of signals revealed that all visual features, from colour to contrast, were equally informative of the extent of prey defence. Our results affirm a central prediction of honesty-based models of signal function and narrow the scope of possible mechanisms shaping the evolution of aposematism. They suggest diverse pathways to the encoding and exchange of information, while highlighting the need for deeper knowledge of the ecology of chemical defences to enrich our understanding of this widespread anti-predator adaptation.
有害化学防御与醒目的警戒色相结合是一种普遍存在的反捕食者策略。此类信号表明防御的存在是其功能所固有的，但它们在定量诚实方面的预期潜力——信号显著性与保护强度的正相关关系——一直是持久争论的主题。在此，我们系统地综合了现有证据，采用荟萃分析来检验这一预测。我们发现了跨分类群的警戒色表达与化学防御程度之间存在正相关的证据。值得注意的是，这种关系在所有尺度上都成立；在个体、种群和物种之间，尽管研究间仍存在大量未解释的异质性。对信号设计的考量表明，从颜色到对比度的所有视觉特征，在表明猎物防御程度方面同样具有信息价值。我们的结果证实了基于诚实性的信号功能模型的一个核心预测，并缩小了塑造警戒色进化的可能机制的范围。它们暗示了信息编码和交换的多种途径，同时强调需要更深入了解化学防御生态学，以丰富我们对这种广泛存在的反捕食者适应的理解。
