Acker P, Grégoire A, Rat M, Spottiswoode C N, van Dijk R E, Paquet M, Kaden J C, Pradel R, Hatchwell B J, Covas R, Doutrelant C
CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier Cedex 05, France.
Laboratoire Évolution & Diversité Biologique (UMR 5174 EDB), Université Toulouse 3 Paul Sabatier - CNRS - ENFA, Toulouse, France.
J Evol Biol. 2015 Nov;28(11):2027-41. doi: 10.1111/jeb.12717. Epub 2015 Sep 14.
Traits used in communication, such as colour signals, are expected to have positive consequences for reproductive success, but their associations with survival are little understood. Previous studies have mainly investigated linear relationships between signals and survival, but both hump-shaped and U-shaped relationships can also be predicted, depending on the main costs involved in trait expression. Furthermore, few studies have taken the plasticity of signals into account in viability selection analyses. The relationship between signal expression and survival is of particular interest in melanin-based traits, because their main costs are still debated. Here, we first determined the main factors explaining variability in a melanin-based trait linked to dominance: the bib size of a colonial bird, the sociable weaver Philetairus socius. We then used these analyses to obtain a measure representative of the individual mean expression of bib size. Finally, we used capture-recapture models to study how survival varied in relation to bib size. Variation in bib size was strongly affected by year and moderately affected by age, body condition and colony size. In addition, individuals bearing small and large bibs had higher survival than those with intermediate bibs, and this U-shaped relationship between survival and bib size appeared to be more pronounced in some years than others. These results constitute a rare example of disruptive viability selection, and point towards the potential importance of social costs incurred by the dominance signalling function of badges of status.
用于交流的特征，如颜色信号，预期会对繁殖成功产生积极影响，但其与生存之间的关联却鲜为人知。以往的研究主要调查了信号与生存之间的线性关系，但根据特征表达所涉及的主要成本，也可以预测出驼峰形和U形关系。此外，很少有研究在生存力选择分析中考虑信号的可塑性。基于黑色素的特征中，信号表达与生存之间的关系尤其令人感兴趣，因为其主要成本仍存在争议。在这里，我们首先确定了解释与优势相关的基于黑色素的特征变异性的主要因素：一种群居鸟类——社交织雀（Philetairus socius）的围涎大小。然后，我们利用这些分析得出一个代表围涎大小个体平均表达的指标。最后，我们使用标记重捕模型来研究生存如何随围涎大小而变化。围涎大小的变异受年份影响很大，受年龄、身体状况和群体大小的影响适中。此外，围涎小和围涎大的个体比围涎中等的个体具有更高的生存率，而且生存与围涎大小之间的这种U形关系在某些年份似乎比其他年份更为明显。这些结果构成了一个罕见的分裂生存力选择的例子，并指出了地位徽章的优势信号功能所产生的社会成本的潜在重要性。
