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Avian Malaria Prevalence Affects Survival in Great Snipe (Gallinago media)
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
Norsk institutt for naturforskning.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
(English)Manuscript (preprint) (Other academic)
National Category
Ecology Zoology
Identifiers
URN: urn:nbn:se:uu:diva-206162OAI: oai:DiVA.org:uu-206162DiVA: diva2:643889
Available from: 2013-08-28 Created: 2013-08-28 Last updated: 2016-09-05Bibliographically approved
In thesis
1. On the Effects of Blood Parasites in Wild Birds
Open this publication in new window or tab >>On the Effects of Blood Parasites in Wild Birds
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Coccidian and haemoatozoan parasites are commonly occurring endo-parasites in wild birds and prevalence can vary among species and populations. In addition to prevalence studies, parasites are often used to investigate effects on life history traits. Findings from these studies are not unambiguous, as correlations with many life history traits are absent, although common findings include negative effects on survival and body condition. In this thesis, coccidian and blood parasite prevalence and their effect on survival were investigated using a PCR approach in eleven popu-lations of great snipes (Gallinago media) and in two populations of tree sparrows (Passer montanus). In great snipes and tree sparrows we investigated the parasites Plasmodium/Haemoproteus (P/H) and Leucocytozoon and in tree sparrows also Atoxoplasma.

In Great snipes the overall adult prevalence was 29.9%. At the main study site, Gåvålia, Norway, a decrease in P/H prevalence with age was found and infected birds had a lower mean age. Two not mutually exclusive alternative explanations are that infected young birds may have a higher mortality and/or that individual birds can purge the infection. There was a variation in prevalence among the sample years in Gåvålia and a difference among populations. Finding fluctuations among year demonstrates the need of long term data to study parasite prevalence variation.  

In tree sparrows the Haematozoan prevalence was 5.9% in adults and 56.5% in Atoxoplasma. By using recapture models to estimate apparent survival rates with the software MARK 4.2, it was suggested that parasite infections may have an impact on the apparent survival rate in one of the populations. Since condition and breeding performance appeared unaffected, it can be hypothesised that this pattern may indicate that chronic infections generally do not appear to impair birds, although subclinical infections may occasionally develop into disease with fatal outcome.

Abstract [sv]

Parasiter är vanliga hos vilda fåglar och de studeras flitigt. Effekten av dem kan vara allt från dödliga till mer eller mindre obefintliga. I den här avhandlingen har jag undersökt förekomst och effekter av två grupper av blodparasiter i två fågelarter med hjälp av molekylära metoder.

Dubbelbeckasinen (Gallinago media) är en lekande migrerande vadare som häckar på fuktiga bergssluttningar i Skandinavien eller i våta flodängar i öster. 30 % av dem är infekterade av någon av parasiterna Plasmodium spp./ Haemproteus spp. eller Leucocytozoon spp som är vektorspridda. Hos fåglar från Gåvålia i Norge minskade förekomsten av parasiter med ålder och fåglar som var infekterade hade en lägre medelålder. Det finns två förklaringar som inte utesluter varandra: (1) Parasiterna leder till en högre dödlighet hos infekterade fåglar, (2) enskilda fåglar kan göra sig av med infektionen. Studien på dubbelbeckasinerna visar på behovet av långa dataserier och många populationer för att upptäcka skillnader i parasitförekomst mellan olika år och populationer.

Pilfinken (Passer montanus) är en stannfågel som häckar i håligheter i träd och den har studerats i två svenska populationer under 5 år. Utöver de parasiter som också studerades hos dubbelbeckasinen, studerades Atoxoplasma spp. som sprids via avföring/födointag. Den här parasitgruppen är dåligt studerad sedan tidigare och effekterna av den är dåligt utredda. Förekomsten av de vektorspridda parasiterna var knappt 6 %, men Atoxoplasma förekom i 56 % av fåglarna. Med hjälp av fångst-återfångstanalys kan det noteras indikationer på parasitinfekterade fåglar hade en lägre årsöverlevnad än oinfekterade en av populationerna. Trots att infektionerna i många fall är kroniska verkar de inte leda till en markant större dödlighet.

Place, publisher, year, edition, pages
Uppsala: Institutionen för ekologi och genetik, 2013. 26 p.
Keyword
Atoxoplasma, avian malaria, coccidia, Gallinago media, Haemoproteus, Leucocytozoon, parasite prevalence, Passer montanus, Plasmodium, recapture mod-els, survival
National Category
Zoology Ecology
Research subject
Biology with specialization in Population Biology
Identifiers
urn:nbn:se:uu:diva-206200 (URN)978-91-506-2367-3 (ISBN)
Presentation
2013-09-20, 1003, Norbyvägen 18D, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2013-09-02 Created: 2013-08-29 Last updated: 2013-09-02Bibliographically approved
2. Host-Parasite Interactions in Natural Populations
Open this publication in new window or tab >>Host-Parasite Interactions in Natural Populations
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Parasitism is one of the most common ways of living and it has arised in many taxa. Parasites feed and live inside or on their hosts resulting in both long and short term consequences for the host. This thesis is exploring the phenotypic and genotypic effects of animals living with parasitic infections. I have been studying three different parasite groups and their associated host species: the great snipe, a lekking freshwater wader bird that migrates between Africa and Northern Europe; the tree sparrow, a stationary passerine found close to human settlements and lastly the water vole, a large rodent living in riparian habitats.

Avian malaria is one of the most commonly studied parasites affecting birds. Atoxoplasma, an intestinal protozoan parasite is less studied but is thought to be endemic in free-ranging birds. Given the freshwater habitat great snipes inhabit, a prevalence of 30% avian malaria infections is not high and that the prevalence fluctuated among years. Sequencing of the avian malaria cytochrome b gene revealed that parasites are similar to avian malaria parasites found in African birds suggesting that they were infected on the wintering grounds in Africa. Tree sparrows had few malaria infected individuals, a result that is consistent with other studies of stationary birds at high latitudes. Atoxoplasma infections were common in tree sparrows and capture-recapture analyses show decreased survival in infected compared to uninfected birds and signs of lower mating success among infected.

Genetic analyses comparing the transcriptome between mated and unmated great snipe males revealed that the genotype is important for mating success and health status for some of the expressed genes. That variations in some of these genes are involved in maintaining a good health status and mating success supports handicap models for sexual selection in this lek mating system.

The major histocompatibility complex (MHC) is a part of the immune system and it contains genes involved in immune response. In water voles, a number of new MHC alleles were identified. Based on their in silico phenotype they were grouped into supertypes to facilitate studies on how helminth infections affect the MHC diversity in the water voles. Some of these MHC supertypes provided resistance to one helminth species, but the same supertype caused the opposite effect for other helminth parasites. Overall, parasites are a driving force for maintaining genetic diversity and parasite infections lowers survival rate, which would lead to a lower lifetime breeding success.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 43 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1395
Keyword
Arvicola terrestris, avian malaria, balancing selection, Major histocompatibility complex, parasitetranscriptome
National Category
Zoology
Research subject
Population Biology
Identifiers
urn:nbn:se:uu:diva-300023 (URN)978-91-554-9633-3 (ISBN)
External cooperation:
Public defence
2016-09-20, Zootissalen, Villavägen 9, Uppsala, 13:00 (English)
Opponent
Supervisors
Funder
Carl Tryggers foundation Swedish Research Council FormasSwedish Research Council FormasLars Hierta Memorial Foundation
Available from: 2016-08-26 Created: 2016-08-01 Last updated: 2016-09-05

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