“…Lower-attine fungi are thought to facultatively associate with ants because the fungi can also live outside the symbiosis 12,21 . In 'higher' attine fungiculture, however, a highly derived group of fungi descended from a lower-attine fungal ancestor is obligately associated with ants and, as far as is known, cannot live outside the symbiosis 13,14,16,17,22,23 .…”