Biogeographical patterns in Panellus stypticus

Abstract

Panellus stypticus fruits widely in Northern Hemisphere temperate forests but has also been collected in Alaska, Costa Rica, Australia and New Zealand. Previous studies established that there was a single biological species across eastern North America, Russia, Japan and New Zealand. In order to examine phylogenetic and biogeographical patterns within this species, the ribosomal ITS1-5.8S-ITS2 region was amplified for 67 collections representing North America, Eurasia, Australia and New Zealand and was sequenced for ten exemplars selected from different geographical areas. The amplified ITS sequence length for collections from New South Wales and Tasmania (Australia) and New Zealand was consistent within each of these geographical areas but varied between areas and was shorter than the ITS region for Northern Hemisphere collections. Length changes were due to a number of deletions. Deleted regions totaled 15 bp in collections from New South Wales, 29 bp from Tasmania and 88 bp from New Zealand. Parsimony analysis based on ITS sequences produced two major clades, a Northern Hemisphere clade and an Oceanian clade. The collection from New South Wales was basal to the Oceanian clade with collections from Tasmania and New Zealand as derived. Restriction fragment length polymorphisms based on BstZ I, Dra I and Hinf I identified several biogeographically separated haplotypes within this species. In the Northern Hemisphere, an eastern North American haplotype was separated from other P. stypticus collections that extended from Pacific North America to Asia. European collections also shared a unique haplotype. The presence of a nuclear ribosomal large subunit group I intron was inferred in all Northern Hemisphere collections and in collections from New South Wales by length variation of the PCR product and by sequencing of selected exemplars. ITS sequence data and the presence of a group I intron in the Northern Hemisphere and New South Wales collections provide evidence that Northern Hemisphere and Southern Hemisphere distributions were connected through South East Asia.