Biological questions and projects
The fundamental questions that I have been curious about concern the evolution of organismal diversity and the factors influencing phenotypic variation. Our work centers on the biological factors influencing naturally occurring variation, from the genotype to phenotype. The research program combines the comparative method of evolutionary biology, genetic and statistical methods and in some cases rely on the tools of molecular biology. The projects ongoing in the lab fall into three main fields, population and evolutionary genetics of salmonids, analyses of experimentally evolved Drosophila, and studies of colonizing insects in Iceland (ants, culicoides and Drosophila sp). In addition we also have several collaborative projects, running or completed (see below).
Population genetics of Arctic charr and Brown trout.
We have run several projects on the evolution and development of Arctic charr (Salvelinus alpinus), in collaboration with Sigurður S. Snorrason, Zophonías O. Jónsson, Sigríður Rut Franzdóttir, Kalina H. Kapralova, at the University of Iceland and some aspects of the work with Bjarni Kr. Kristjansson and Skúli Skúlason (at Holar University). Benedikt Hallgrímsson at University of Calgary and and Ian M. Dworkin at McMaster University collaborate on projects investigating divergence, plasticity and craniofacial diversity in Arctic charr. Arctic charr invaded multiple rivers and lakes in the northern hemisphere following the last glaciation (about 12,000 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 contributions to this project are on population and evolutionary genomics of charr. We also implemented a large experiment of plasticity and divergence in sympatric charr morph from lakes, and an anadromous population, that was supervised by postdoc and now collaborator Sarah. E. Steele (at the Canada museum in Ottawa). Following this we have started analyzing variation in feeding structures, focusing on shape of the jaw bones and dentary variation. Guðbjörg Ósk Jónsdóttir completed her Masters project on thais project, 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 focus on gene expression in response to 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 worked on this project and Dagný Ásta Þórhölludóttir (then Runarsdottir) 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 ants, Drosophila species and small biting midges. The ant project is run by Phd. student Marco Mancini and M.Sc. student Andreas Guðmundsson - see more at maurar.hi.is. Marco completed his M.Sc. thesis in 2022 and found that four species of ants that have settled in Iceland and 20+ 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 studies by Andreas and Marco on the 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:
Variation in the serum proteome of humans - led by Valborg Guðmundsdóttir and Hulda K. Ingvarsdóttir at Icelandic heart association (Hjartavernd).
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 projects
About a decade a go we started a collaboration with Richard Hudson and Marcos Antezana at the University of Chicago, on the 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 was funded by the Icelandic research council, the University of Iceland research fund. It completed without clear results.
Another previous grant of note was an International reintegration grant from the Marie Curie program of the EU, on evolution of DNA repair and somatic mutations. Project is on hold.
Doctoral and post-doctoral projects
My doctoral thesis at NC State University was on the quantitative genetics and evolution of wing shape in fruitflies. The project was initiated by Greg Gibson (now at Georgia Tech) and now the torch is being carried by Ian Dworkin now at McMaster University, Canada. Through a series of experiments on Drosophila melanogaster we managed to map a QTL for wing shape down to a nucleotide change in the promoter of the Epidermal growth factor receptor locus. 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 three year 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. 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. 3) The third main project was to screen for genetic variations in other characterized enhancers in D. melanogaster. We found very little variation, with the exception of two large deletions in the enhancers of EVE, both of which took out binding sites for Hunchback TF.
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.