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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 [en]
Arvicola terrestris, avian malaria, balancing selection, Major histocompatibility complex, parasitetranscriptome
National Category
Zoology
Research subject
Population Biology
Identifiers
URN: urn:nbn:se:uu:diva-300023ISBN: 978-91-554-9633-3 (print)OAI: oai:DiVA.org:uu-300023DiVA: diva2:950703
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
List of papers
1. Avian Malaria Prevalence Affects Survival in Great Snipe (Gallinago media)
Open this publication in new window or tab >>Avian Malaria Prevalence Affects Survival in Great Snipe (Gallinago media)
(English)Manuscript (preprint) (Other academic)
National Category
Ecology Zoology
Identifiers
urn:nbn:se:uu:diva-206162 (URN)
Available from: 2013-08-28 Created: 2013-08-28 Last updated: 2016-09-05Bibliographically approved
2. Blood transcriptomes and de novo identification of candidate loci for mating success in lekking great snipe (Gallinago media)
Open this publication in new window or tab >>Blood transcriptomes and de novo identification of candidate loci for mating success in lekking great snipe (Gallinago media)
Show others...
2017 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 26, no 13, 3458-3471 p.Article in journal (Refereed) Published
Abstract [en]

We assembled the great snipe blood transcriptome using data from fourteen lekking males, in order to de novo identify candidate genes related to sexual selection, and determined the expression profiles in relation to mating success. The three most highly transcribed genes were encoding different haemoglobin subunits. All tended to be overexpressed in males with high mating success. We also called single nucleotide polymorphisms (SNPs) from the transcriptome data and found considerable genetic variation for many genes expressed during lekking. Among these, we identified 14 polymorphic candidate SNPs that had a significant genotypic association with mating success (number of females mated with) and/or mating status (mated or not). Four of the candidate SNPs were found in HBAA (encoding the haemoglobin a-chain). Heterozygotes for one of these and one SNP in the gene PABPC1 appeared to enjoy higher mating success compared to males homozygous for either of the alleles. In a larger data set of individuals, we genotyped 38 of the identified SNPs but found low support for consistent selection as only one of the zygosities of previously identified candidate SNPs and none of their genotypes were associated with mating status. However, candidate SNPs generally showed lower levels of spatial genetic structure compared to noncandidate markers. We also scored the prevalence of avian malaria in a subsample of birds. Males infected with avian malaria parasites had lower mating success in the year of sampling than noninfected males. Parasite infection and its interaction with specific genes may thus affect performance on the lek.

National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-300021 (URN)10.1111/mec.14118 (DOI)000403695500012 ()28345264 (PubMedID)
Funder
Carl Tryggers foundation Swedish Research Council
Available from: 2016-08-01 Created: 2016-08-01 Last updated: 2017-09-25Bibliographically approved
3. Fitness Effects of Coccidian and Avian Malaria Parasites in Tree Sparrows
Open this publication in new window or tab >>Fitness Effects of Coccidian and Avian Malaria Parasites in Tree Sparrows
(English)Manuscript (preprint) (Other academic)
National Category
Zoology
Research subject
Population Biology
Identifiers
urn:nbn:se:uu:diva-300020 (URN)
Funder
Lars Hierta Memorial FoundationSwedish Research Council Formas
Available from: 2016-08-01 Created: 2016-08-01 Last updated: 2016-09-05Bibliographically approved
4. Relationship between helminth infections and MHC class II supertype diversity in natural water voles (Arvicola amphibius) populations
Open this publication in new window or tab >>Relationship between helminth infections and MHC class II supertype diversity in natural water voles (Arvicola amphibius) populations
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Zoology
Identifiers
urn:nbn:se:uu:diva-300022 (URN)
Funder
Carl Tryggers foundation Swedish Research Council
Available from: 2016-08-01 Created: 2016-08-01 Last updated: 2016-09-05Bibliographically approved

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