We investigated the population structure of two foliar fungal endophyte species, Lophodermium fissuratum and L. nitens, across a north–south gradient in the Pacific Northwest. Using ddRADSeq and demographic modeling, we found that both species diverged prior to the Last Glacial Maximum, but differed in timing, gene flow, and levels of isolation. Our findings extend the Soltis Line, a known phylogeographic boundary, to include fungal endophytes, revealing that even closely related fungi with shared hosts can have distinct evolutionary histories.
