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Immunoglobulin level and infection intensity influence how malaria-infected collared flycatchers respond to brood size manipulation
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
Swedish Institute for Communicable Disease Control, Stockholm, Sweden.
Swedish Institute for Communicable Disease Control, Stockholm, Sweden.
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(English)Article in journal (Refereed) Submitted
Abstract [en]

1.The existence of a trade-off between investment in reproduction and immune function is well-established in many species. However, variation in the underlying physiological allocation strategies, which is what selection operates on, remains largely unexplored.

2.We investigated how haemosporidian infection influenced stress hormone level and ability to increase parental effort in female collared flycatchers (Ficedula albicollis). We especially focused on how estimates of investment in humoral immune response and level of parasitemia influenced subsequent parental investment (i.e. offspring provisioning and offspring mass).

3.To achieve these goals, we combined a brood size manipulation experiment with nested- and quantitative PCR methods to establish infection status and intensity. In addition, we quantified immunoglobulin Y (IgY) and stress protein levels.

4. Malaria-infected females reared enlarged broods with lower mass but there was large variation in their response to the experiment. Only infected females with low IgY levels decreased their relative provisioning rate and there was a positive relationship between the intensity of infection and total brood mass.

5. Our study implies that malaria-infected flycatchers experience a trade-off between keeping their infection at bay (i.e. low level of parasitemia) and responding to increased offspring demands (i.e. high offspring mass in enlarged broods). However, relatively immunocompetent individuals (i.e. individuals with high IgY levels) did not compromise their parental care suggesting that the main cost of raising the immune response does not lay in antibody production.

Keyword [en]
Avian malaria, Haemoproteus, life-history strategy, parental effort, Plasmodium
National Category
URN: urn:nbn:se:uu:diva-204309OAI: oai:DiVA.org:uu-204309DiVA: diva2:638260
Available from: 2013-07-29 Created: 2013-07-29 Last updated: 2015-11-24Bibliographically approved
In thesis
1. Avian malaria, life-history trade-offs and interspecific competition in Ficedula flycatchers
Open this publication in new window or tab >>Avian malaria, life-history trade-offs and interspecific competition in Ficedula flycatchers
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis investigates the impact of avian malaria (Haemosporidia) parasites on the outcome of interspecific competition between two closely related bird species, pied (Ficedula hypoleuca) and collared (F. albicollis) flycatchers. I further investigated how variation in timing of breeding, life history strategies and immune competence genes (MHC genes) modulate the fitness effects of malaria parasites in one of the two species i.e. collared flycatchers. Collared flycatchers colonized the Baltic island Öland in the late 1950-ties and has since then been expanding their breeding range while competitively excluding pied flycatchers from the favourable habitats (deciduous forests). I investigated the underlying mechanisms behind this exclusion by combining detailed long-term breeding data with modern molecular genetic techniques identifying both the presence/absence and lineage specificity of haemosporidian blood parasites. I found that the rapid decline of pied flycatchers can be explained by the combined effects of competition over nestling sites, hybridization and haemosporidian infections. Haemosporidian infections have a negative impact on survival of pied flycatcher females but no detectable effect on collared flycatchers’ longevity or reproductive success. This may be due to the fact that collared flycatchers carry (and are potentially exposed to) a higher diversity of parasites than pied flycatchers, which in turn may select for a higher diversity of MHC genes and hence a better overall protection from the negative impact of parasites. Indeed, functional MHC diversity correlates negatively with malaria prevalence among collared flycatchers from Gotland. Moreover, I found that both, malaria infection intensity and immunoglobulin level influences how infected collared flycatchers respond to increased nestling food-demands. The latter results mean that there is variation in allocation strategies (i.e. in resource allocation between reproductive effort and immune competence) within the collared flycatcher population. Hence, this population has the ability to respond to novel selection pressures in terms of optimal allocation of resources into immune functions. In summary, my results show that local parasites may facilitate the expansion of a new colonizer. This is important in the context of global climate change that will probably increase the colonization rate of southern species and lead to novel host-parasite interactions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 59 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1056
Blood parasites, competitive asymmetry, immunocompetence, interspecific competition, life-history trade-offs, MHC, parasite-driven selection
National Category
urn:nbn:se:uu:diva-204349 (URN)978-91-554-8708-9 (ISBN)
Public defence
2013-09-13, Zootisalen, Evolution Museum Building, Uppsala, 10:00 (English)
Available from: 2013-08-23 Created: 2013-07-31 Last updated: 2015-11-24Bibliographically approved

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