Abstract
The forces that maintain stable species boundaries are poorly characterized in Fungi. In many other organisms, forces such as assortative mating or large structural changes in the genome are sufficient to prevent hybridization. Yet, these barriers are either largely absent or uncommon in most Fungi. Here, we use a pan-genomic approach in the globally distributed ectomycorrhizal fungus Boletus edulis Bull. with 295 whole genome sequences and 22 newly generated reference genomes to identify whether changes in genome structure or ecologically relevant gene families are necessary to maintain lineage segregation in the presence of ongoing gene flow. Here, we show that B. edulis possesses one of the most diverse pan-genomes of all eukaryotes. Lineages within B. edulis are actively hybridizing but gene flow does not correlate with genome structural similarity or overall gene content. Inversions and translocations can harbor highly divergent loci, but likely are not necessary or sufficient for reproductive isolation. Instead, we find that the composition of biodegradation or effector proteins more accurately predicts the presence of gene flow among lineages and B. edulis as a group may specialize on chitin decomposition. Altogether, we show that ecological preferences are the primary driver of speciation in B. edulis.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Updated version February 2024. Manuscript and figures have been revised.
