Supporting data for: A Natural Hybrid Zone Between Divergent Ecotypes of a Wood-Decay Fungus in Fennoscandiahttps://doi.org/10.18710/SQ8XSOEkeberg, Ingvild MyhreDataverseNO2026-06-222026-06-22T11:05:47ZPostglacial migration out of glacial refugia has led to secondary contact between diverging lineages, creating numerous contact zones across European taxa. In fungi, especially in wood-decay fungi, such contact zones have been poorly studied. Yet, contact zones are natural “evolutionary experiments” where speciation, reproductive barriers and hybrid zone dynamics can be studied. We investigated the population structure, hybrid zone dynamics and demographic history of the wood-decay fungus Meruliopsis taxicola in Fennoscandia, using whole-genome resequencing data combined with distribution modelling. Our results show that there exist two ecologically and genomically divergent ecotypes of M. taxicola in Fennoscandia, corresponding to a Coastal and Continental ecotype, which probably diverged during the last glaciation and subsequently migrated into Fennoscandia. Moreover, the ecotypes are mating, and there is a narrow hybrid zone between the distributions of the ecotypes. The nature of the hybrid zone remains unclear, but there is evidence suggesting that there is asymmetrical gene flow from the Continental ecotype to the Coastal ecotype. Future work should test hypotheses regarding hybrid fitness through phenotypic experiments to conclude further about the pattern of asymmetrical introgression, and the stability of the hybrid zone.Medicine, Health and Life Scienceshybrid zonesecondary contactadaptationdemographypopulation genomicswood-decay fungiEnglishSubmitted for review2026-06-22Ekeberg, Ingvild MyhreSkrede, IngerKauserud, HåvardNaas, Adam EindrideKrabberød, Anders KristianPeris, DavidBysting, Anne KragDavid, MarieHofton, Tom Hellik2025-11-212020-10-012025-12-012020-10-012025-12-01Whole genome sequencing dataVCFNorwaySwedenFinlandCaucasusRussian FederationCC0 1.0