The study shows that commercial cultivars of the mushroom Psilocybe cubensis lack genetic diversity because of their domestication for human use. Meanwhile, a naturalized population of mushrooms in Australia has maintained much more diversity, they show, including unique gene variants controlling the production of the mushroom's active ingredient, psilocybin.

"What was surprising was the extreme homozygosity of some cultivars of magic mushroom," says Alistair McTaggart of The University of Queensland, Australia. "Some of these cultivars have been nearly stripped of any diversity except at their genes controlling sexual reproduction."

"Whether this happened intentionally, by targeted inbreeding to fix traits over the last half century, or unintentionally through a lack of diversity to cross against is hard to know," he says. "The trailblazers who domesticated magic mushrooms have set the stage for how we can advance cultivation and innovate with shrooms as we improve our understanding of psilocybin and its benefits."

McTaggart says that research into these mushrooms has been driven by an underground community of people interested in magic mushrooms, many of whom are co-authors on the new study. With no financial support for the effort, the wider community of people interested in magic mushrooms collected the cultivars and isolates under study, sending samples at their own expense and risk. Ultimately, the researchers sequenced and assembled DNA data for more than 100 varieties of magic mushrooms.