Evolution of Antarctic lichens revealed by phylogenetic analyses

Abstract

The Antarctic is defined geographically as all lands and adjoining ice shelves south of latitude 60？S. Floristically, the Antarctic possesses two vascular plants and diverse bryophytes and lichens. The Antarctic is one of the best places for studying the evolution of lichen-forming fungi because of its geographical locality and diversity of lichens. Lichens are symbiotic organisms of mycobionts (fungi) and photobionts (algae or cyanobacteria). They constitute the main part of Antarctic flora, along with algae and bryophytes. Some lichens are natures pioneers that are the first to penetrate into the areas emerging from beneath the ice, and have a successful evolutionary strategy to adapt in extreme environmental conditions, and have resulted in diverse, abundant, and important flora in the terrestrial ecosystem of Antarctica. Molecular phylogenetic studies have provided new insights to understanding the evolutionary relationships among phenotiypically recognized species. Recently, collaborative studies among classical taxonomists and molecular phylogeneticists have resulted in a revised classification system of fungi. By extensive molecular phylogenetic studies, many new insights have been found on the matter of polyphyletic taxonomic groups, development of cryptic species, and morphological variation by genetic diversity, geographical distribution, and environmental adaptation. It is now generally accepted that combining morphological and molecular phylogenetic analyses leads to a better understanding of fungal relationships and biodiversity. In this study, results of molecular phylogenetic studies of Cladonia, Pseudephebe, Umbilicaria and Usnea are presented. The fruticose lichen Cladonia borealis grows on soil and humus, sometimes among mosses in light and dry places and is found in polar and subpolar areas. In order to investigate genetic variation and geographical distribution of C. borealis from the Antarctic, 50 samples from King George Island (the Antarcti