Reticulate evolution and rapid development of reproductive barriers upon secondary contact in a forest fungus

Reproductive barriers between sister species of the mushroom-forming fungi tend to be stronger in sympatry, leading to speculation on whether they are being reinforced by selection against hybrids. In this study, we use population genomic analyses together with in vitro crosses of a global sample of the wood decay fungus Trichaptum abietinum to investigate reproductive barriers within this species complex and the processes that have shaped them. Our phylogeographic analyses show that T. abietinum is delimited into six major genetic groups, one in Asia, two in Europe, and three in North America. The two groups present in Europe are interfertile and admixed, whereas our crosses show that the North American groups are reproductively isolated. In Asia, a more complex pattern appears, with partial intersterility between multiple sub-groups that likely originated independently and more recently than the reproductive barriers in North America. We found pre-mating barriers in T. abietinum to be..., , , # Reticulate evolution and rapid development of reproductive barriers upon secondary contact in a forest fungus [https://doi.org/10.5061/dryad.z8w9ghxnw](https://doi.org/10.5061/dryad.z8w9ghxnw) VCF-file containing whole genome genetic variation of a global dataset of the wood decay fungus *Trichaptum abietinum*. ## Description of the data and file structure illumina_1_2_3_4_hf_excl_DP3_GQ20_nomono_noindel_nodik_miss20.vcf.gz is a gzipped VCF-file obtained from GATK4´s pipeline of joint variant discovery by running Haplotypecaller in GVCF mode with ploidy = 1, followed by GenomicsDBImport and GenotypeGVCFs to produce the GVCF-file containing the joint variants in the data. The GVCF-file was quality filtered using BCFtools 1.10.275 following an approach outlined in Barth et al. 2019 ([https://doi.org/10.1111/mec.15010)](https://doi.org/10.1111/mec.15010) to obtain the current VCF-file. The filtering thresholds were set to exclude sites that have: FS > 40, MQRankSum < −5.0 || > 5.0, ...,