Experimental evolution of external immune defences in the red flour beetle.
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.
Department of Experimental Ecology, Institute of Integrative Biology (IBZ), Zürich, Switzerland; Department of Evolutionary Ecology and Genetics, Zoological Institute, University of Kiel, Kiel, Germany.
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G
Joop
O
O
Roth
P
P
Schmid-Hempel
J
J
Kurtz
D000704:Analysis of Variance; D000818:Animals; D001173:Arthrobacter / Q000187:drug effects; D005075:Biological Evolution; D049628:Body Size; D004926:Escherichia coli / Q000187:drug effects; D006458:Hemolymph / Q000201:enzymology; D064307:Microbiota / Q000187:drug effects / Q000276:immunology*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010858:Pigmentation / Q000502:physiology; D011809:Quinones / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D012641:Selection, Genetic; D012737:Sex Factors; D016019:Survival Analysis; D014231:Tribolium / Q000276:immunology* / Q000378:metabolism
D011809:Quinones; D014442:Monophenol Monooxygenase
Tribolium castaneum; ecological immunology; experimental evolution; innate immune defence; phenoloxidase; quinone secretion; quinones