| Fungi play major roles in all facets of modern ecosystems as decomposers, mutualists, parasites, and pathogens with all other organisms. However, only approximately 950 fossil fungi have been described in a taxonomic sense; of these, the number that have been found in association with other organisms measures in the mere dozens. Many paleobotanical studies have been completed that indicate large-scale changes in vegetational communities over geologic time, but no such studies have been attempted for the fungal components of those communities. This study examines the epiphyllous fungal components of one locality and compares it to other similar localities in the past and present to determine the taxonomic changes over time at the community level.; The locality used is from the Miocene of Clarkia, Idaho, and represents a humid subtropical climate. The locality is composed of a diverse plant assemblage, providing a diversity of fungi, and the preservation is exceptional. The results of this study document a wide variety of epiphyllous fungi at the Clarkia locality, contradicting previous fungal investigations from the site. These results bolster the interpretation that the climate in Idaho in the mid-Miocene was subtropical. Comparisons with other fossil and extant localities indicate that taxonomic diversity in epiphyllous fungal communities has increased over time. Additionally, this study suggests that there has been an abrupt shift in dominance from the Dothideales to hyphomycetes in subtropical epiphyllous fungal communities between the Miocene and the present. Reasons could include rapid pre-infection burial, ultraviolet exposure differences, or specific interfungal interactions shifting the balance of the community. However, this shift disappears at the ordinal level if only fungi found exclusively on living leaves are considered, which could indicate that the Miocene localities are representative of living communities. If fungi from other sites like the Clarkia locality are exhaustively sampled, it is highly possible that intra-site shifts in fungal community structure similar to that in modern successional studies could be found. These could be used as comparisons to other contemporaneous localities to infer possible successional stages, and thereby indicate whether the fungi were saprobes or symbionts without evidence of ultrastructural host response. |
