Evolution and geographical distribution of the lichen genus Usnea in Antarctic

Abstract

Phylogenetic relationships of Usnea spp. from different localities in Antarctic were reconstructed based on combined sequences of ITS and 28S rDNA. From the tree, geographical isolation of Usnea spp. in Antarctic was not evident. Instead, samples from different area were clustered together, implying that lichen-forming fungal species are widely distributed in Antarctic. Usnea spp. from King Jeorge Island looked isolated from those of continent. Presence and absence of introns may provide information for the distribution of Usnea species. In this study, samples with close phylogenetic relationships had different pattern in possession of introns, implying that introns are easily lost or obtained. However, sequences of introns were generally well conserved in the same phylogenetic lineages. Sharing of same intron sequences by lichens from different geographical origin supports the hypothesis of easy geographical distribution of lichen species in Antarctic continent.