The research in our lab uses a mixture of genomic and experimental approaches to understand what factors are driving the evolution of complex life forms. Our study system comprises species of the fungal model systems Neurospora and Podospora, but we are also studying non-model basidiomycetes and lichens. Below, specific aspects of our work are highlighted:
Today, it is widely accepted that conflicts caused by selfish genetic elements is a driving force for evolutionary innovation, and hence, is of fundamental importance for all aspects of evolution. Nevertheless, empirical data on the topic is largely lacking. In our research, we use the filamentous ascomycetes Neurospora and Podospora as study systems of the evolutionary significance of meiotic drive. In these sexual eukaryote model systems, meiotic drive elements called Spore killers are found. The cytological properties and natural distribution of Spore killing in these fungi has been investigated for several decades, and preliminary data suggests that it is an important driver of both genome evolution and of higher-order evolutionary processes. We currently build a tool-kit of genomic and experimental resources to i) identify and characterize the gene(s) encoding Spore killer elements, ii) assess the strength of Spore killers as meiotic drivers, iii) unravel their evolutionary histories, and iv) investigate the association between Spore killer and genome architecture, mating-system transitions and speciation. Our research on the Spore killers is done in collaboration with Fons Debets and colleagues at Wageningen University, Dave Jacobson at Stanford University, and Tom Hammond at Illinois State University.
A heterokaryon is a tissue type composed of cells containing genetically different nuclei. Heterokaryosis is commonly found in ascomycete and basidiomycete fungi, and is expected to results in two fundamental challenges for the organism: the coordination of populations of nuclei for growth and development of the mycelium, and the suppression of nuclear competition during reproduction and dispersal. Ongoing research in the group focuses on the interactions between nuclei of fungal heterokaryons. We experimentally investigate the strength of intraorganismal selection, and patterns of conflict and cooperation at the nuclear level. We also study the molecular basis for nuclear communication. For our lab experiments, we use the model system Neurospora: N. crassa and N. tetrasperma, the latter being heterokaryotic for mating-type throughout its life cycle. We also extend our work to include field investigations of natural heterokaryons in basidiomycetes forming fairy rings, which grow as a heterokaryotic mycelium from a single focal point in extending ring patterns, thereby being suitable as naturally occurring evolution experiments.
Lichens constitute a group of apparently successful symbiotic organisms, covering a large fraction of the earth surface and can grow on almost any substrate. The aim of the work is to understand the lichens symbiosis using an evolutionary approach and the worm lichen, Thamnolia vermicularis, and the Letharia vulpina as model systems. The worm lichen, Thamnolia vermicularis, is found in many arctic and alpine localities all over the world, and in Sweden it has a special distribution occurring both in alvar areas on Öland and Gotland and in the Swedish Laplandic mountains. Due to its distribution in Sweden, the worm lichen is a suitable organism for a study on local adaptation of lichenized fungi in response to climatic change. The wolf lichen, Letharia vulpina, grows naturally in open forests on the dead or living bark of conifers, but it can also occasionally be found on wooden manmade artifacts such as phone poles. The limited and shrinking distribution of the wolf lichen to old-growth forests of Sweden, raises important questions with regard to its biology and life strategies and therefore efficient conservation strategies. We are currently exploring genomic data from these two lichen species, and use these to answer questions related to evolutionary history and reproductive mode.