Joop G, Roth O, Schmid-Hempel P, Kurtz J
Department of Experimental Ecology, Institute of Integrative Biology (IBZ), Zürich, Switzerland; Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, Kiel, Germany.
J Evol Biol. 2014 Aug;27(8):1562-71. doi: 10.1111/jeb.12406. Epub 2014 May 19.
The red flour beetle, Tribolium castaneum, secretes quinones that control the microbial flora in the surrounding environment. These secretions act as an external immune defence that provides protection against pathogens. At high concentrations, however, these secretions are harmful to the host itself, and selection may thus have optimized the level of expression under natural conditions. Here, we show that the expression of external immunity responded to selection during experimental evolution within a few generations. At the same time, one component of internal immune defence (phenoloxidase activity) was compromised in beetles selected for either high or low external defences. Intriguingly, offspring protection against a natural pathogen was reduced in flour obtained from beetle lines selected for low amounts of secretions. Altogether, this suggests that external and internal immune defences work together efficiently under natural conditions, whereas every manipulation on the side of external immune defence comes with costs to the internal immune defence.
赤拟谷盗（Tribolium castaneum）会分泌醌类物质，这些醌类物质可控制周围环境中的微生物群落。这些分泌物起到外部免疫防御的作用，为抵御病原体提供保护。然而，在高浓度时，这些分泌物对宿主自身有害，因此自然选择可能在自然条件下优化了其表达水平。在此，我们表明，在实验进化过程中，外部免疫的表达在几代之内就对选择做出了响应。与此同时，在被选择用于高或低水平外部防御的甲虫中，内部免疫防御的一个组成部分（酚氧化酶活性）受到了损害。有趣的是，在从分泌量低的甲虫品系获得的面粉中，后代对天然病原体的抵抗力降低了。总体而言，这表明在自然条件下，外部和内部免疫防御能有效地协同工作，而对外部免疫防御的任何操作都会给内部免疫防御带来代价。
