Magic mushrooms, which produce the compound psilocybin, maintain sexual compatibility across geographically isolated populations despite minimal gene flow since diverging from a common ancestor. Analysis of 89 genomes shows that psilocybin genes have high allelic diversity and show signs of balancing selection. Australasia is the center of origin for wood-degrading magic mushrooms, and their intercontinental distribution likely resulted from human-assisted movement of woodchips, mulch, or plants rather than natural dispersal. The findings indicate that species connectivity persists across separated populations, with no evidence of allopatric speciation eroding mating compatibility.
Psilocybe subaeruginosa, a wood-degrading magic mushroom that produces the psychedelic compound psilocybin, is structured by geography across its Australian range, but geographically separated populations remain fully sexually compatible. Genetic analyses of 89 isolates show that allelic diversity at mating compatibility and psilocybin loci likely results from genetic drift and minimal gene flow since divergence from a common ancestor. Movement of woodchips, mulch, or plants has probably spread genotypes locally within Australia and to the northern hemisphere. Northern-hemisphere species P. azurescens and P. cyanescens cluster among Australian populations, suggesting they are the same species as P. subaeruginosa, whose centre of origin is Australasia. High allelic diversity occurs in psilocybin pathway genes, with some haplotypes carrying one or two putatively functional copies of psiH, though the duplication's functionality remains unknown.