Molecular phylogenetics suggest a North American link between the anthropogenic dry rot fungus Serpula lacrymans and its wild relative S. himantioides

Abstract

The dry rot fungus Serpula lacrymans causes damages in wooden buildings and constructions in temperate regions worldwide. In this study, the global phylogeography of S. lacrymans and its wild relative S. himantioides has been investigated to clarify genealogical relationships and determine the origin and spread of the building strains. Internal transcribed spacer (ITS) nrDNA and parts of the beta-tubulin (tub) and the translation elongation factor (efa) 1a genes were sequenced, and phylogenetic relationships inferred. Some analyses suggest that S. lacrymans may have originated from an ancient S. himantioides lineage, but most results support that S. lacrymans and S. himantioides are monophyletic sister species. Phylogenetic analysis of the ITS data revealed two subgroups within S. lacrymans corresponding to two earlier described varieties; one group occurring frequently in houses worldwide ('Domesticus'), and one group represented by individuals from forests in Northern California ('Shastensis'). A few collections from nature were included in the Domesticus group as well, among other specimens from two newly discovered localities in Far East Russia and Siberia. In the Domesticus group little sequence variation occurs, suggesting a recent worldwide dispersal, possibly linked to human activity. Phylogenetic analyses indicate that the Domesticus group may have originated from an ancient lineage related closely to the Shastensis group. A remarkable shift in morphology and habitat preferences has occurred during the evolution of the Domesticus lineage, linked to the transition from nature to human-made habitats.