Supervisors: prof. Urmas Kõljalg ja teadur Leho Tedersoo
Opponent: lektor (PhD) Rasmus Kjoller (Kopenhaageni Ülikool)
This thesis examines the community structure, species richness and biogeography of Alnus-associated ectomycorrhizal (EcM) fungi from local to global scales. Alnus has a wide geographical range of distribution and low richness of fungal symbionts, which enables to address the following hypothesis: 1) host species and their phylogenetic
relationships account for the strongest predictor of EcM fungal community composition at the intrageneric level at the global scale; 2) at regional scale, soil conditions such as pH and phosphorus concentration drive the EcM community structure rather than geographical and host genetic distance; 3) at global scale, Alnus-associated EcM fungal species richness is largely determined by the mean annual temperature and precipitation; 4) global biogeography of Alnus EcM communities reflects ancient migration routes of host.
The main results and conclusions are the following 1) phylogenetic relations
among hosts account for strongest predictor of EcM community structure, while
geographical and edaphic variables have a relatively low impact at the global
scale; 2) at the regional scale edaphic variables were the dominant determinants of EcM fungal community structure; 3) soil calcium accounted for the key determinant of Alnus-associated EcM fungal species richness at the global scale, while soil humidity was the most influential at the local and regional scales; 4) Beringia is likely to be primary migration route of Alnus from Eurasia to America rather than North Atlantic land bridge 5) high similarity between North and South Europe probably results from recent post-glacial recolonisation.