Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway.
PLoS One. 2012;7(4):e34281. doi: 10.1371/journal.pone.0034281. Epub 2012 Apr 6.
A surging interest in the evolution of consistent trait correlations has inspired research on pigment patterns as a correlate of behavioural syndromes, or "animal personalities". Associations between pigmentation, physiology and health status are less investigated as potentially conserved trait clusters. In the current study, lice counts performed on farmed Atlantic salmon Salmo salar naturally infected with ectoparasitic sea lice Lepeophtheirus salmonis showed that individual fish with high incidence of black melanin-based skin spots harboured fewer female sea lice carrying egg sacs, compared to less pigmented fish. There was no significant association between pigmentation and lice at other developmental stages, suggesting that host factors associated with melanin-based pigmentation may modify ectoparasite development to a larger degree than settlement. In a subsequent laboratory experiment a strong negative correlation between skin spots and post-stress cortisol levels was revealed, with less pigmented individuals showing a more pronounced cortisol response to acute stress. The observation that lice prevalence was strongly increased on a fraction of sexually mature male salmon which occurred among the farmed fish further supports a role for steroid hormones as mediators of reduced parasite resistance. The data presented here propose steroid hormones as a proximate cause for the association between melanin-based pigmentation and parasites. Possible fundamental and applied implications are discussed.
对稳定特征相关性进化的浓厚兴趣激发了人们对色素模式作为行为综合征（即“动物个性”）相关物的研究。与色素沉着、生理和健康状况相关的关联作为潜在的保守特征群研究较少。在当前的研究中，对自然感染了外寄生虫海虱 Lepeophtheirus salmonis 的养殖大西洋三文鱼 Salmo salar 进行的虱子计数表明，与色素沉着较少的鱼类相比，具有高发生率的黑色黑色素基皮肤斑点的个体鱼携带带有卵囊的雌性海虱较少。色素沉着与其他发育阶段的虱子之间没有显著关联，这表明与黑色素基色素沉着相关的宿主因素可能会在更大程度上改变外寄生虫的发育，而不是定居。在随后的实验室实验中，皮肤斑点与应激后皮质醇水平之间呈现出强烈的负相关，色素沉着较少的个体对急性应激表现出更为明显的皮质醇反应。在养殖鱼类中，一部分性成熟的雄性三文鱼上虱子的流行率强烈增加，这一观察结果进一步支持了类固醇激素作为降低寄生虫抵抗力的中介的作用。这里提出的数据表明，类固醇激素是黑色素基色素沉着与寄生虫之间关联的一个直接原因。讨论了可能的基础和应用意义。
