Admixture in the fungal pathogen Blastomyces.

Blastomyces is an emerging primary fungal pathogen that affects patients worldwide. The evolutionary processes that have resulted in the current diversity in the genus remain largely unexplored. We used whole genome sequences from 99 Blastomyces isolates, including two sequenced in this study using long-read technologies, to infer the phylogenetic relationships between Blastomyces species. We find that five different methods infer five different phylogenetic trees. Additionally, we find gene tree discordance along the genome with differences in the relative phylogenetic placement of several species of Blastomyces, which we hypothesize is caused by introgression. Our results suggest the urgent need to systematically collect Blastomyces samples around the world and study the evolutionary processes that govern intra- and interspecific variation in these medically important fungi.