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Costs of inflammatory and humoral immune responses in the subterranean rodent Ctenomys talarum: Linking immune variability and life history underground
CUTRERA AP; MERLO JL; ZENUTO RR; LUNA F
Congreso; 12th International Mammalogical Congress; 2017
Theimmunological variation of wild populations in relation to life-history traitshas recently become a central topic in evolutionary biology, given the criticalcontribution of immunity to an individual?s fitness. Specific induced defenses,which require substantial time and resources and are mostly beneficial againstrepeated infections, are expected to be favored in ?slow-living? species. Totest this prediction, understanding the costs and benefits of immunity isessential. Here, we evaluated the energetic costs of activating two differentarms of immune defense (humoral and inflammatory) in the Argentine subterraneanrodent Ctenomys talarum (tuco-tucos), a ?slow-living? species. While asignificant increase in oxygen consumption was verified when tuco-tucos mountedan antibody-mediated immune response against sheep red blood cells (SRBC), nosignificant energetic cost was detected during the inflammatory responsetriggered by phytohemagglutinin (PHA), which in tucos has components of theinnate as well as the adaptive response. However, PHA-induced inflammation wasnegatively affected by infection with naturally-occurring gastrointestinalparasites and in animals under food restriction, suggesting that currenciesother than energy are mediating the costs of inflammation in tuco-tucos. Whenboth arms of defense were activated simultaneously, we found no evidence thatthe humoral response was favored over the inflammatory response, despitetuco-tucos? slow pace of life. The relevance of other factors, such as pathogenexposure in the subterranean environment and the low basal metabolic rate oftuco-tucos, is discussed in relation to the immune variability exhibited bythese rodents, and the implications for natural populations of wild mammals.