Contrasting demographic histories revealed in two invasive populations of the dry rot fungus Serpula lacrymans

Globalization and international trade have impacted living organisms around the world leading to a considerable number of species establishing in new geographic areas. Many organisms have taken advantage of human-made environments, including buildings. One such species is the dry rot fungus Serpula lacrymans, which is the most aggressive wood-rotting fungus in indoor environment in temperate regions. Using population genomic analyses of 36 full genome sequenced isolates we revealed that isolates from Europe and Japan are highly divergent and split between 3,000 - 19,000 generations ago, probably predating human influence. Approximately 250 generations ago, the European population went through a tight bottleneck, corresponding to the time it colonized the built environment. Islands of low differentiation was found in genes related to important functions of growth and intracellular transport related to its specialized natural habitat. These functions may have enabled both populations to independently establish in the human-made environment. Moreover, we included two isolates from New Zealand, one of which showed evidence of admixture between the European and Japanese populations.