Drosophila Adaptation to Viral Infection through Defensive Symbiont Evolution |
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Authors: | Vitor G Faria Nelson E Martins Sara Magalh?es Tania F Paulo Viola Nolte Christian Schl?tterer élio Sucena Luis Teixeira |
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Institution: | 1Instituto Gulbenkian de Ciência, Oeiras, Portugal;2Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal;3Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria;4Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal;Fred Hutchinson Cancer Research Center, UNITED STATES |
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Abstract: | Microbial symbionts can modulate host interactions with biotic and abiotic factors. Such interactions may affect the evolutionary trajectories of both host and symbiont. Wolbachia protects Drosophila melanogaster against several viral infections and the strength of the protection varies between variants of this endosymbiont. Since Wolbachia is maternally transmitted, its fitness depends on the fitness of its host. Therefore, Wolbachia populations may be under selection when Drosophila is subjected to viral infection. Here we show that in D. melanogaster populations selected for increased survival upon infection with Drosophila C virus there is a strong selection coefficient for specific Wolbachia variants, leading to their fixation. Flies carrying these selected Wolbachia variants have higher survival and fertility upon viral infection when compared to flies with the other variants. These findings demonstrate how the interaction of a host with pathogens shapes the genetic composition of symbiont populations. Furthermore, host adaptation can result from the evolution of its symbionts, with host and symbiont functioning as a single evolutionary unit. |
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