In the project, we use a combination of experimental and correlative approaches to investigate whether accelerated telomere degradation is a causative mechanism through which small immune costs can accumulate over time and later be translated into senescence and reduced Darwinian fitness. Immune costs may also be ‘hidden’ because of sex-specific (sexually antagonistic) effects. Another part of the project therefore focuses on how such effects may affect immune gene variation, immune costs and Darwinian fitness. These aspects are central for advancing our understanding of the evolution of disease resistance and immune function, incl. immune system over-reactions (autoimmunity).
To address our research objectives, we use different study systems:
- We make use of a unique study system encompassing 33 years of blood samples, pedigree, and lifetime reproductive success information from a wild songbird population subjected to selection in their natural environment: the great reed warbler population at lake Kvismaren. We use this system to (i) investigate sex-specific selection on immune gene diversity (number of alleles, antigen recognition repertoire and (ii) to study the association between malaria infection, life history strategies and ageing patterns with special focus on telomere attrition. In addition, we also collaborate with Prof Pavel Zehtindjiev’s research group at the Institute of Biodiversity and Ecosystem Research in Sofia, Bulgaria, to (iii) conduct malaria infection experiments on captive great reed warblers to investigate sex-specific patterns of induced immune responses, gene expression and translation of mild disease into physiological senescence
- We use laboratory-housed populations of birds (domesticated canaries, zebra finches) to conduct large-scale long-term experiments investigating the physiological mechanisms underlying the trade-offs between disease resistance and fitness. Here, too, a key aspect is telomere dynamics as a potentially major physiological mechanism mediating costs of seemingly mild (benign) disease and immune responses. We investigate (i) the functional importance of telomere length (TL) as a currency mediating adverse effects of (mild) disease into physiological costs, and (ii) the cumulative effect of chronic disease on physiological health and immunosenescence. Furthermore, we aim to (iii) disentangle trans-generational (parental) effects on offspring early life TL (eTL), and (iv) test if the remarkable positive relationship between eTL and life span is caused by a positive effect of longer eTL on immune performance and physiological quality. For the canary project, we collaborate with Prof Gediminas Valkiūnas research group at the Nature Research Centre in Vilnius, Lithuania.
- Roved, J., Hansson, B., Tarka, M., Hasselquist, D.‡ & Westerdahl, H.‡ 2018. Sexually antagonistic selection on MHC diversity in a wild songbird. Proceedings of the Royal Society B 285: 20180841 (‡ shared last author).
- Asghar, M., Palinauskas, V., Zaghdoudi-Allan, N., Valkiūnas, G., Mukhin, A., Platonova, E., Färnert, A., Bensch, S. & Hasselquist, D. 2018 Parallel telomere shortening in multiple body tissues owing to malaria infection. Proceedings of the Royal Society B 283: 20161184.
- Asghar M, Hasselquist, D, Hansson B, Zehtindjiev P, Westerdahl H & Bensch, S. 2015. Hidden costs of infection: chronic malaria accelerates telomere degradation and senescence. Science 347:436-438.
- Gediminas Vlkiūnas, Nature Research Centre, Lithuania
- Pavel Zehtindjiev, Institute of Biodiversity and Ecosystem Research, Bulgaria
Advanced Grant from the European Research Council (ERC)