Globalization and international trade have impacted 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-decay
fungus in indoor environments in temperate regions. By using population
genomic analyses of 36 full genome sequenced isolates, we revealed that
isolates from Europe and Japan are highly divergent and that these
populations split 3,000 - 19,000 generations ago, probably predating
human influence. Approximately 250 generations ago, the European
population went through a tight bottleneck, likely corresponding to the
time it colonized the built environment. Moreover, evidence of admixture
between European and Japanese populations was shown in an isolate from
New Zealand. Genomic analyses revealed that low differentiation appeared
in genes with functions related to of growth and intracellular
transport, possibly important to its ability to effectively decay large
substrates. These functions may have enabled both populations to
independently establish in the human-made environment. Further,
selective sweep analyses identified rapid changes in genes possibly
related to decay of various substrates in Japan and in genes involved
DNA replication and protein modification in Europe. These two fungal
populations were preadapted to the built environment, but have more
recently and independently adapted to their local environment.
Contrasting demographic histories revealed in two invasive populations of the dry rot fungus Serpula lacrymans