Species Diversification of the Coniferous Pathogenic Fungal Genus Coniferiporia (Hymenochaetales, Basidiomycota) in Association with Its Biogeography and Host Plants

Abstract

Coniferiporia, belonging to Hymenochaetaceae and now segregated from Phellinidium, is a wood-inhabiting fungal genus with three species, each having a specific geographic distribution and a strong host specificity as a forest pathogen of coniferous trees. In this study, the species diversity of Coniferiporia is further clarified with the aid of a wider sampling and multilocus-based phylogenetic analysis, which reveals a new species Coniferiporia uzbekistanensis. The molecular clock and ancestral geographic origin analyses indicate that the ancestor of Coniferiporia emerged in one of the Pinaceae and Cupressaceae, then jumped to the other plant family originated in eastern Eurasia 17.01 million years ago (Mya; 95% highest posterior density: 9.46 to 25.86 Mya), and later extended its distribution to western North America, Central Asia, and eastern Europe. Coniferiporia sulphurascens speciated on Pinaceae in eastern Eurasia 8.78 Mya (9.46 to 25.86 Mya) and then extended its distribution to western North America and eastern Europe. Coniferiporia qilianensis and C. uzbekistanensis speciated on Juniperus przewalskii in eastern Eurasia 3.67 Mya (0.36 to 8.02 Mya) and on Juniperus polycarpos in Central Asia 4.35 Mya (0.94 to 8.37 Mya), respectively. The speciation event of Coniferiporia weirii occurred 4.45 Mya (0.77 to 9.33 Mya) right after the emergence of its host, the endemic Cupressaceae species Thuja plicata, and soon after, this fungus evolved to also inhabit another endemic Cupressaceae species Calocedrus decurrens. In summary, this study for the first time unambiguously clarified and timed the adaptive evolutionary event of Coniferiporia in association with its biogeography and host plants.