Molecular Ecology and Immunoecology

To understand the diversity of life, evolutionary biologists of the past century studied adaptations as phenotypically expressed traits, and used quantitative genetic theory and breeding experiments to unravel the underlying genetics. Recent advances in molecular biology will now make it possible to study the ecology of genes directly in natural populations.

 This research field, known as "Molecular Ecology", is one of the most rapidly expanding branches of biology. We have developed a strong research profile in applying molecular techniques to a broad array of research topics in evolutionary ecology. Molecular methods we are using include, for example, DNA-fingerprinting, microsatellite analysis, DNA sequencing, cloning of repetitive and single copy DNA, DGGE, RAPD, AFLP, SNP, construction of c-DNA libraries, reverse transcriptase PCR and real-time PCR. We have also a strong profile in immunoecology, studying how the immune system is related to stress, individual quality and fitness. Organisms presently studied in our group include birds (>20 species), fish (Salmonids, sticklebacks, guppies), mammals (wolf), reptiles (adders, python, sand lizards), insects (blackflies, butterflies) and parasites (avian malaria, zoonotic bacteria and virus).

Molecular studies of "good genes" 

The effects of nutrition and oxidative stress on the expression of male ornaments, such as song repertoire size and carotenoid pigmentation, in birds are experimentally studied to reveal the causal links between sexual ornaments and individual fitness. We also compare data on individual MHC genotype/haplotype with life- history data in atlantic salmon, great reed warblers, Seychelles warbler, sand lizards, adders and python, to establish whether there is an association between allelic variation in the immune system and various fitness traits. In one research project we study the effects of specific MHC alleles on disease resistance in Atlantic salmon. (TvS, MH, DH, LR, TM, HWi, ÅL, JL, HWe, KP, DR)

Oxidative stress and the detoxication system

Many environmental chemicals are, in an evolutionary sense, new and in many cases they have unknown toxic effects in their original form but become highly toxic due to their activation of the detoxication enzymes. One important inducer of the detoxication process is the Ah receptor which binds to certain dioxin- related compounds and initiates the transcription of a battery of individual detoxication enzymes, ultimately leading to a state of oxidative stress. In both mammals and fishes the Ah receptor genes have allelic polymorphism that convey differences in the bearers' susceptibility to dioxin. By molecular analyses we characterise the Ah receptor genes and its allelic variants in Atlantic salmon in order to evaluate the importance of genetic variation of the Ah receptor for the evolution of tolerance towards exposure to persistent organochlorine pollutants. This project is in cooperation with the Department of Chemical Ecology and Ecotoxicology.
(TvS, HWi, JL, KP, MH)

Dispersal and inbreeding 

Dispersal at the level of individuals affects the genetic structure of populations, ultimately influencing population features such as the level of inbreeding and the potential for local adaptations to occur. We routinely use microsatellite markers to resolve relatedness between individuals. To examine how dispersal affect inbreeding and fitness, we use data from long term studies of great reed warblers (20 years), Siberian jays (29 years) and Seychelles warblers (20 years), in populations where the overwhelming majority of birds have been individually marked. The genetic diversity and relatedness in the Scandinavian wolf population is studied with 30 microsatellite markers, as a part of the SKANDULV project. (SB, BH, HWe, DH, BGL, DR, KP)

Population structure and local adaptations

Genetic population structure in relation to post-glacial colonization patterns is studied in e.g. dunlins, curlew sandpipers, willow warblers, greenish warblers, chiffchaffs, icterine/melodiuos warblers and great reed warblers by analyses of microsatellite markers, AFLP and mitochondrial DNA sequencing. In particular, we study the evolution of migratory behavior and song, and use natural hybrid zones between recently differentiated subspecies to decipher the underlying genetics of these traits.  (SB, BH, LW, SÅ, JS, DH, JPT)

Immunoecology: immunocompetence in the context of sexual selection and life history theory

The research project focuses on evolutionary and ecological aspects of the immune system, mainly in birds. In particular, we have developed modern methods in immunology (enzyme-linked immunosorbant assay; ELISA) that give us unique opportunities to measure humoral immunocompetence in passerine birds. We are investigating immunocompetence in relation to work load (physical stress), nutrition, parasite load, steroid hormones, and mating and reproductive success in e.g. blue tits, pheasants, red-winged blackbirds, tree swallows and song sparrows. Also, in collaboration with Maria Sandell (Lund Univ.), we study maternal transfer of antibodies via egg yolk to offspring; patterns of transfer and effects on young in e.g. blue tits, pheasants, starlings and jackdaws.  (DH, LR, MS)

Sexual selection and mating systems 

The research aims at identifying different selective agents that affect the individuals' reproductive success in territorial bird species; one precocial species the pheasant, and one altricial species the great reed warbler. The main questions examined are: (1) does female mate choice discriminate between genotypic quality and/or phenotypic resources, and (2) to what extent does variation in secondary sexual characters reflect genotypic quality and/or phenotypic resources. Traditional ecological methods, e.g. individual marking, radio-tracking and observational studies, as well as ELISA based measurements of immunocompetence and molecular methods for parentage determination and PCR-based sexing, are used to single out the paths of selection and to estimate fitness. 
(TvS, DH, LR, SB, HWe, BH, DR)

Systematics and Evolution of Avian Malaria 

Blood samples taken from wild animals may contain DNA from parasites like malaria. We study such "foreign" DNA by the PCR technique, obtaining sequences of the parasites cytochrome b gene, enabling unequivocal assignment of parasite lineages. Most passerine species appear to be infected by 1-5 different malaria lineages and cross species infection is common between closely related bird hosts. Most of these parasite lineages seem to represent species, because they are associated with unique sequences at a nuclear locus. We study this complex host-parasite system in terms of time and space of transmission, and parasite lineage dependent host fitness, in forest and reed bed bird communities, both in European summer quarters and on African wintering grounds. 
(SB, MS, SÅ, DH, HWe, BH, JPT, OH, DR)

Ecology, Epidemiology and Evolution of Bird-borne Zoonotic Diseases 

A majority of the microorganisms that inflict disease in humans are zoonotic, meaning that they have the capacity of transmitting between animal reservoirs and humans. Despite this important fact, pathogens are seldom studied in natural wild animal populations, and thus the major body of published works have either a strict human or a strict veterinary medicine focus. In our collaboration studies with Björn Olsen (Umeå Univ.), we have a multi-disciplinary approach involving human and veterinary medicine and animal ecology, studying pathogens and their ecology and epidemiology in wild animals. Primarily we focus on (1) enteric bacterial pathogens, as Campylobacter spp., Helicobacter spp. and Salmonella spp., and (2) viral zoonoses such as West Nile virus and Avian influenza, and the prevalence and distribution of these microorganisms in wild birds in relation to ecological characteristics of their hosts. Genetic relatedness between bacterial isolates of different origin is analysed for evolutionary studies of bacterium - host interactions and for estimating the frequency of pathogen transmission between reservoirs. (JW, DH, SB)

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Graduate programs

Mikael Åkesson: 

Heritability and development of quantitative traits in the great reed warbler

Olof Hellgren: 

Biodiversity in a parasite host system: Blood parasites, culicoides vectors and avian hosts

Sara Naurin:

Ecological Genomics in the Great Reed Warbler, Acrocephalus arundinaceus