While postglacial migration patterns have been well-studied in plants and animals in Europe, the same is not true for microorganisms such as fungi, and it remains unclear whether fungi have followed the same postglacial migration trajectories. Our main aim in this study was to trace the post-glacial history of the wood decay fungus T. abietinum in Europe by asking whether recolonization of northern Europe has happened from multiple refugia. We hypothesise that T. abietinum has co-migrated together with its main host trees from different Southern and Eastern European refugia. Further, we ask if there has been secondary contact between lineages spreading from separate refugia, and whether contact zones among them can be found. Since the fungus has multiple host tree species that resided in different refugia, we hypothesize that admixture of lineages from different refugia has taken place, leading to a complex genetic structure in European populations of T. abietinum. To test these hypotheses, we conducted detailed population genomic analyses of genetic diversity and demographic history based on available full genome sequences of a large set of European samples of T. abietinum.

BWA, 0.7.17

GATK4, 1.4.0

BCFtools, 1.10.2

PLINK, 1.9

Filtered Illumina DNA sequence data of Trichaptum in the form of single nucleotide polymorphic (SNP) data files (VCF) used for population genomic analyses.