Multiple gene genealogies reveal recent dispersion and hybridization in the human pathogenic fungus Cryptococcus neoformans

Cryptococcus neoformans (= Filobasidiella neoformans) is a significant emer ging fungal pathogen of humans. To understand the evolution of this pathoge n, 34 strains were obtained from various locations around the world and fra gments of four genes were sequenced from each. These strains represented al l three varieties and five serotypes. The four sequenced genes are: (i) the mitochondrial large ribosomal subunit RNA; (ii) the internal transcribed s pacer region of the nuclear rRNA, including ITS1, 5.8S rRNA subunit and ITS 2 (iii) orotidine monophosphate pyrophosphorylase; and (iv) diphenol oxidas e. Phylogenetic analyses indicated considerable divergence among lineages, which corresponded to the current classification of C. neoformans into thre e varieties. However, there is no apparent phylogeographic pattern. Signifi cant incongruences were observed among gene genealogies. The analyses indic ated that the major lineages in C. neoformans diverged tens of millions of years ago but have undergone recent dispersion and hybridization.