The evolution of immune defense and song complexity in birds
The evolution of immune defense and song complexity in birds
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DOI：
10.1554/0014-3820(2003)057
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发表时间：
2003-04-01
期刊：
影响因子：
3.3
通讯作者：
Erritzoe, J
中科院分区：
文献类型：
--
作者：
Garamszegi, LZ;Moller, AP;Erritzoe, J
有三个主要假设可以解释寄生虫毒力的进化如何与第二性特征的进化联系在一起，比如鸟鸣。首先，由于汉密尔顿和祖克提出了寄生虫在性选择中的作用，在寄生严重的物种中，雌性偏爱健康的雄性可能会导致过度的特征表达。其次，如果性选择本身通过选择增强的毒力来影响宿主-寄生虫相互作用的共同进化动态，那么可能会出现反向因果机制。第三，睾丸激素的装饰或有限的资源对免疫的抑制作用可能会导致具有复杂歌曲的物种对寄生虫的易感性增加。假设寄生虫的毒力和宿主对免疫防御的投入之间存在共同进化关系，我们使用免疫功能和鸣叫复杂性的测量方法在雀形目鸟类的比较研究中验证了这些假设。在前两个假设下，我们预测鸟类鸣叫的复杂性与物种间的免疫防御呈正相关，而如果免疫抑制起作用，这种关系预计是负的。我们发现，成年T细胞介导的免疫反应和Fabricius法氏囊的相对大小与歌曲复杂性的衡量标准独立地呈正相关，即使潜在的混杂变量保持不变。雏鸟的T细胞反应与歌唱的复杂性无关，可能反映了年龄相关的选择性对宿主免疫防御的压力。我们的结果与预测歌曲复杂性和免疫功能之间存在正相关关系的假设是一致的，从而表明寄生虫在性选择中发挥了作用。免疫系统的不同组成部分可能独立地参与了这一过程。
There are three main hypotheses that explain how the evolution of parasite virulence could be linked to the evolution of secondary sexual traits, such as bird song. First, as Hamilton and Zuk proposed a role for parasites in sexual selection, female preference for healthy males in heavily parasitized species may result in extravagant trait expression. Second, a reverse causal mechanism may act, if sexual selection affects the coevolutionary dynamics of host-parasite interactions per se by selecting for increased virulence. Third, the immuno-suppressive effects of ornamentation by testosterone or limited resources may lead to increased susceptibility to parasites in species with elaborate songs. Assuming a coevolutionary relationship between parasite virulence and host investment in immune defense we used measures of immune function and song complexity to test these hypotheses in a comparative study of passerine birds. Under the first two hypotheses we predicted avian song complexity to be positively related to immune defense among species, whereas this relationship was expected to be negative if immuno-suppression was at work. We found that adult T-cell mediated immune response and the relative size of the bursa of Fabricius were independently positively correlated with a measure of song complexity, even when potentially confounding variables were held constant. Nestling T-cell response was not related to song complexity, probably reflecting age-dependent selective pressures on host immune defense. Our results are consistent with the hypotheses that predict a positive relationship between song complexity and immune function, thus indicating a role for parasites in sexual selection. Different components of the immune system may have been independently involved in this process.