Summary
We are using molecular genetics techniques to investigate (a) the overall level of genetic diversity in Antarctic mosses, (b) the spatial arrangement and mutation levels within populations, (c) their taxonomic relationships and origins, (d) the effect of climate change on mutation levels, and (e) the source of colonising propagules on recently exposed or disturbed ground. We have used the RAPD (Random Amplified Polymorphic DNA) technique to investigate the extent of genetic diversity within colonies, within populations, and among distinct populations of several moss species collected mainly in the Ross Sea region. The RAPD method was chosen for these initial studies because it can be applied to single moss shoots, many samples can be analysed relatively quickly and inexpensively, and comparisons can be made in the absence of other genetic information. The RAPD technique has also proven useful in assisting with Antarctic moss taxonomy, where this has previously been difficult due to the phenotypic plasticity displayed by these plants in the harsh environment. Results so far have shown that genetic variation does occur in Antarctic moss populations, and is more extensive than expected for most species, although the level of diversity also depends to some extent on the type of habitat and environment. We have also determined the main methods of local dispersal for four moss species in Antarctica, and demonstrated the genetic and spatial relationships between moss colonies found along the length of small meltstream drainage channels for five species. For example, dispersal of B. pseudotriquetrum was clearly assisted by water down a very isolated drainage channel, as colonies were identical or very similar genetically to those further down the channel. Similarly, B. argenteum was locally water-dispersed, as colonies from five different drainage channels in Garwood Valley were clustered according to both the channel from which they were collected, and also their