Pacific boletes: implications for biogeographic relationships

Abstract

The obligate association of boletes with their plant partners is critical to understanding biogeographic distribution of these fungi. Only in rare instances are boletes not obligatory associates of plants; the majority are presumed or proven partners in obligate symbioses with a variety of plants. The array of plant-associated distributions provides a potential handle for evaluating bolete distribution on a global scale. However, migration processes remain unclear and distributions are often disjunct. As an illustration of phylogeographic studies of putatively widespread bolete taxa, we present preliminary analyses for Tylopilus ballouii using LSU rDNA and RPB1 sequence data. The LSU data suggest geographic structuring of the tested accessions. However, RPB1 data indicate that long-distance dispersal events (possibly mediated by humans) are possible, or that selection or other factors have obscured geographical patterns. Molecular divergence between samples in RPB1 argues against panmixis, and indicates that populations have been isolated for long periods.