Biological questions and projects

The fundamental questions that I have been curious about concern the diversity and evolution of organisms and factors influencing phenotypic variation. Our work centers on the biological factors influencing naturally occurring variation, across the multiple dimensions of phenotype and genotype. The research program uses the quantitative thinking of evolutionary biology with some forays into molecular biology. The projects ongoing in the lab fall into three main fields, population or evolutionary genetics of salmonids, analyses of experimentally evolved Drosophila, and studie of colonizing insects in Iceland (ants, culicoides and Drosophila sp). but we also have other collaborative projects running.

Population genetics of Arctic charr and Brown trout.

We have several projects on the evolution and development of Arctic charr (Salvelinus alpinus), in collaboration with Sigurdur S. Snorrason, Zophonias O. Jonsson, Sigríður Rut Franzdóttir, Kalina H. Kapralova, at the University of Iceland and some aspects of the work with Bjarni Kr. Kristjansson and Skuli Skulason (at Holar University). Benedikt Hallgrimsson and Ian M. Dworkin at University of Calgary and McMaster University respectfully collaborate on the study of plasticity and craniofacial diversity in Arctic charr. This charr is curious in that it invaded multiple rivers and lakes in the northern hemisphere following the last glaciation (about 12000 years ago). Ecologists have documented extensive variation in trophic morphology accompanying these invasions into new habitats, including formation of dwarf morphs in multiple springs and lakes. Our main contributions are on population and evolutionary genomics of charr, in collaboration with the charr team. The largest experiment was a study of plasticity and divergence in local populations and sympatric charr, supervised by post doc Sarah. E. Steele. In junction with that we have also started analyzing variation in internal structures, focusing on shape of the jaw bones mainly. Guðbjörg Ósk Jónsdóttir completed her Masters project on that topic, and has now started her Ph.D. Several other collaborative projects sprung from the Plasticity project, not detailed here.

See more on bleikja.hi.is.

Evolution of regulatory DNA: transcriptional cooption and transcriptional decay.

We are studying the regulatory evolution of compensatory evolution and genetic assimilation, in collaboration with Ian Dworkin at McMaster University. We study the expression dynamics under strong selection, and test specific models on the co-evolution of transcription factors and regulatory DNA. We are currently working on analyzing two RNA-seq dataset from experimental lineages of flies that Sudarshan Chari and Sarah Marzec in the Dworkin lab generated. Their experiments involved artificial selection for modifiers suppressing a major mutation and selection for crossveinless phenotypes following heat shock (aka Waddington and Patton). Baldur Kristjánsson works on this project. Dagný Ásta Rúnarsdóttir completed her M.Sc. on the vestigial gene suppression.

Ant and wild fly projects

We have also started mapping colonization of insects in Iceland, focusing on Drosophila species and ants. The ant project is run by M.Sc. student Marco Mancini and Andreas Guðmundsson - see more at maurar.hi.is. Marco has now completed his M.Sc. thesis and in it he describes four species of ants that have settled in Iceland and 20 or so more that are either occasional visitors or settle sporadically before collapsing or being exterminated. Manuscript on this is in the works, and as are follow up studied of two ant species that can live outdoors in Iceland.

Other collaborations

During the last few years I have been fortunate enough to help with evolutionary studies on various system, for instance:

Genetics and plasticity in fish behavior - Marion Dellinger and David Benhaim.

ATG7 molecular evolution - with Margret Helga Ogmundsdottir and Valgerður J. Hjaltalín.

Evolution of the env gene during MVV infection - with Valgerdur Andresdottir and collaborators.

Gene expression in symbiosis during temperature stress - with Silke Werth, Olafur S. Andresson and Sophie Steinhauser.

The evolution and transcription dynamics of MITF and related TFs - with Eirikur Steingrimsson, Margret Helga Ogmundsdottir and Francesca Pignoni.

 

Previous work (Epistasis in genome wide data - terminated project).

The third main project was a collaboration with Richard Hudson and Marcos Antezana at the University of Chicago, which involved development of methods to detect epistasis in data from genome wide association tests on disease status. Daniel Oskarsson (a Ph.D. student) worked on this project.

The work is funded by the Icelandic research council, the University of Iceland research fund.

Previous grants include International reintegration grant from the Marie Curie program of the EU.

Previous work (doctorate and post-doctoral projects)

My doctoral work centered on the quantitative genetics and evolution of wing shape in flies. The project was initiated by Greg Gibson at NC State (now at Georgia Tech) and now the torch is being carried by Ian Dworkin then at Michigan State University, East Lansing. Through a series of experiments we managed to map a QTL for wing shape down to a nucleotide change in the promoter of the Epidermal growth factor receptor locus in Drosophila melanogaster.  Quite impressively, Ian has found this association also in wild caught flies. Ian and I are still collaborating on wing projects, including an experiment to replicate the Egfr wing shape association in flies with gain of function mutations in Egfr.

For a post doc I worked with Martin Kreitman and Misha Ludwig at the University of Chicago, focusing on variation in embryonic features in flies. The work consisted of three main projects. 1) Misha had refined a transgenic system to test whether even-skipped (eve) stripe 2 enhancer from different species can complement an artificially generated deficiency in this regulatory element in D. melanogaster. We designed methods for quantifying the abundance of EVE protein in the embryo which allowed us to demonstrate that strains carrying these genetic constructs showed significant differences in EVE concentration possibly due to dose and species of origin. Most bafflingly, the D. erecta stripe 2 enhancer failed to complement while the more distantly related enhancer from D. pseudoobscura did. This work is presented in a paper in PLOS Biology. 2) Building on this project, I also collaborated with Susan Lott, a graduate student in the lab, on ways to quantify variation in the magnitude, spacing and timing of expression of early developmental genes in D. melanogaster. The aim was to quantify variation in mRNA levels for eve and other early development transcription factors across inbred lines and species in the Drosophila species group.

During a 9 month stint at Decode genetics, I worked on various projects relating to the genetics of complex disease. One was a collaboration with researchers at Aarhus University, the University of Oxford and Nijmegen University, aimed at developing new statistical methods for detecting disease variants. I also screened regions implicated in genome wide association studies for putative regulatory variants, as for instance in the case of Myocardial Infarction, where the strongest signal mapped to a chromosome region containing regulatory DNA and helped with studies on pigmentation genetics.