Department of Biology, McMaster University, , Hamilton, Ontario, Canada, Institute of Natural and Mathematical Sciences, Massey University, , Albany Campus, Auckland, New Zealand.
Proc Biol Sci. 2013 Nov 27;281(1775):20132680. doi: 10.1098/rspb.2013.2680. Print 2014 Jan 22.
Signals of dominance and fighting ability (i.e. status signals) are found in a wide range of taxa and are used to settle disputes between competitive rivals. Most previous research has considered status-signal phenotype as an attribute of the individual; however, it is more likely that signal expression is an emergent property that also incorporates aspects of the social environment. Furthermore, because an individual's signal phenotype is likely to influence its social interactions, the relationships between status signals, social environment and individual quality are probably much more complex than previously appreciated. Here, we explore the dynamic relationship between social interactions and signal expression in a previously undescribed status signal, the frontal shield of the pukeko (Porphyrio porphyrio melanotus: Aves). We demonstrate that frontal shield size is a strong predictor of dominance status within social groups, even after controlling for potentially confounding variables. Then, we evaluate the relationship between social interactions and signal expression by testing whether manipulating apparent shield size influences (i) dominance interactions and (ii) future signal expression. By showing that decreasing apparent shield size causes both an increase in the amount of aggression received and a decrease in an individual's true shield size, we provide the first evidence of dynamic feedback between signal expression and social interactions. Our study provides important insight into the role of receiver-dependent (i.e. social) costs in maintaining signal honesty and demonstrates a unique approach to studying status signalling applicable to future studies on dynamic morphological signals.
在广泛的分类群中都存在着支配力和战斗能力（即地位信号）的信号，并被用于解决有竞争力的对手之间的争端。大多数先前的研究都将信号表现型视为个体的属性；然而，更有可能的是，信号表达是一种突现的特性，也包含了社会环境的各个方面。此外，由于个体的信号表现型可能会影响其社交互动，因此地位信号、社会环境和个体质量之间的关系可能比以前所认识的要复杂得多。在这里，我们探索了在一个以前未被描述的地位信号——新西兰国鸟几维鸟（Porphyrio porphyrio melanotus：鸟类）的额盾——的社交互动和信号表达之间的动态关系。我们证明，即使在控制了潜在的混杂变量后，额盾大小仍然是群体内支配地位的一个强有力的预测指标。然后，我们通过测试操纵明显的盾大小是否会影响（i）支配力的相互作用和（ii）未来的信号表达，来评估社交互动和信号表达之间的关系。通过表明减小明显的盾大小会导致接收到的攻击量增加和个体真实盾大小的减少，我们提供了信号表达和社交互动之间存在动态反馈的第一个证据。我们的研究为接受者依赖（即社会）成本在维持信号真实性方面的作用提供了重要的见解，并展示了一种适用于未来动态形态信号研究的独特的地位信号研究方法。
