Sockman Keith W
Department of Biology and Curriculum in Neurobiology University of North Carolina, Chapel Hill.
Anim Behav. 2009 Mar;77(3):663-671. doi: 10.1016/j.anbehav.2008.11.016.
Morphology may affect behavioural performance through a direct, physical link or through indirect, secondary mechanisms. Although some evidence suggests that the bill morphology of songbirds directly constrains vocal performance, bill morphology may influence vocal performance through indirect mechanisms also, such as one in which morphology influences foraging and thus the ability to perform some types of vocal behaviour. This raises the possibility for ecologically induced variation in the relationship between morphology and behaviour. To investigate this, I used an information theoretic approach to examine the relationship between bill morphology and several measures of vocal performance in Lincoln's sparrows (Melospiza lincolnii). I compared this relationship between two breeding seasons that differed markedly in ambient temperatures, phenology of habitat maturation, and food abundance. I found a strong curvilinear relationship between bill shape (height/width) and vocal performance in the seemingly less hospitable season but not in the other, leading to a difference between seasons in the population's mean vocal performance. Currently, I do not know the cause of this annual variation. However, it could be due to the effects of bill shape on foraging and therefore on time budget, energy balance, or some other behavioural or physiological response that manifests mostly under difficult environmental conditions or, alternatively, to associations between male quality and both vocal performance and bill shape. Regardless of the cause, these results suggest the presence of an indirect, ecologically mediated link between morphology and behavioural performance, leading to annual variation in the prevailing environment of acoustic signals.
形态学可能通过直接的物理联系或间接的次级机制影响行为表现。虽然一些证据表明鸣禽的喙形态直接限制了发声表现，但喙形态也可能通过间接机制影响发声表现，比如一种形态学影响觅食从而影响执行某些类型发声行为能力的机制。这就增加了形态学与行为之间的关系因生态因素而产生变化的可能性。为了对此进行研究，我采用了一种信息论方法来检验林肯雀（Melospiza lincolnii）的喙形态与几种发声表现指标之间的关系。我比较了在环境温度、栖息地成熟物候以及食物丰富度方面存在显著差异的两个繁殖季节之间的这种关系。我发现在看似条件较差的季节里，喙的形状（高度/宽度）与发声表现之间存在很强的曲线关系，而在另一个季节则不存在，这导致了两个季节种群平均发声表现的差异。目前，我尚不清楚这种年度变化的原因。然而，这可能是由于喙的形状对觅食的影响，进而对时间分配、能量平衡或其他一些主要在困难环境条件下表现出来的行为或生理反应产生影响，或者是由于雄性质量与发声表现和喙的形状之间的关联。无论原因是什么，这些结果表明形态学与行为表现之间存在一种间接的、由生态介导的联系，导致声学信号的主要环境出现年度变化。
