The history of conifers in central Italy supports long-term persistence and adaptation of mesophilous conifer fungi in Arbutus-dominated shrublands

Abstract

A mycological survey from Monti della Tolfa, a volcanic region of central Italy that originated during the Early Pleistocene and remained isolated from the mainland for at least one million years, shows that a thermophilous shrubland dominated by Arbutus unedo preserves fungal species typically associated with conifers. Pinaceae are currently absent from the study area. Palynological data from the same region show a decline of Abies and Picea around 70 ka BP and their complete disappearance during the Holocene. Pinus disappeared during the postglacial. This may have determined first the isolation of the fungal populations in relict conifer woodlands in Monti della Tolfa, and then their adaptation to the current habitat, which was favored by the presence of Arbutus unedo, a broadly receptive species towards fungal associates. Genetic sequences of an isolate of Amanita muscaria (fly agaric) from Monti della Tolfa indicate that our individual is more closely related to North American than to Eurasian populations and add new insights into the phylogeographic processes of this globally distributed species.