Summary
Mosses are the dominant plant species in continental Antarctica, where they sparsely colonize the limited stony coastal areas not permanently covered with snow and ice. The few species of mosses present in Antarctica live ‘‘on the edge’’ for plant life, surviving in some of the harshest conditions on Earth with extremes of cold, drought, light, and wind. Reproduction is usually by local dispersal of vegetative propagules, and colonization of new locations is very difficult; immigration from other land masses appears infrequent. Moreover, in this region mosses are already exposed to increased levels of UV-B irradiation due to the yearly expansion of the ozone hole and global warming. We have been using techniques of molecular genetics (RAPDs and DNA sequencing) to investigate the biodiversity of Antarctic mosses, population relationships, dispersal and colonization, and mutation. We have also used genetics to determine the identity of some mosses that have proven difficult or impossible to characterize due to their phenotypic plasticity in Antarctica. In addition, we have been able to demonstrate dispersal of different species by either wind or water, and to show dispersal over very short distances of a few meters in frost channels. We have initiated investigation of mutagenesis in Antarctic mosses, both by studying relationships of shoots within individual colonies and by analyzing long shoots cut into small sections. For long shoots, where estimates of growth rates are 0.1–1 mm per year maximum, 10 cm shoots probably represent 100 years of growth. We have detected occasional mutations within such shoots, as well as in different shoots of the same colony—the further shoots are apart within the colony, the more mutations we can detect. The combination of RAPDs and DNA sequencing is proving a powerful method for investigation of the mutation, evolution, and colonization of mosses in Antarctica, and we present here the novel results of our recent investigations.