Speciation is the process where new species evolves, typically happening when one genetic lineage of interbreeding individuals splits into two lineages not able to reproduce. However, sometimes well-differentiated lineages may also fuse back into one lineage. This can be referred to as reverse speciation. The wood decay fungus Meruliopsis taxicola provides an opportunity to explore this process. There are two well-differentiated ecotypes of M. taxicola, one ‘lowland type’, growing strictly on Pinus sylvestris in coastal areas in Norway and another ‘highland type’ growing on logs of Picea abies in continental areas. In between these two types, hybrids can be found that can grow on both substrates. In parts of Northern Europe, where the two types have co-existed for longer time (e.g. Finland), the fusion of the two lineages has apparently gone further than in other areas (e.g. Norway).
In this project, the master student will isolate fungal cultures of the two types, as well as the intermediate hybrids, from the field. It will then be possible to investigate their physiological properties in vitro, in regard to substrate specialization and climate adaptation. In the lab, the isolates growth rate and decay efficiency will be tested at different temperatures and water potentials, as well as on different wood substrates. The physiological experiments will provide information on why the two well-differentiation lineages fuse back into one lineage. The obtained culture collection will form the basis for further studies investigation at a genomic level.
Supervisors
Håvard Kauserud, Inger Skrede and Sundy Maurice (all Evogene).