Summary
The extent of genetic variation and dispersal mechanisms were investigated over short distances of 1 – 100 m and up to 3 km, by the RAPD technique, for the moss Sarconeurum glaciale at three locations on Ross Island, Antarctica. At Arrival Heights, genetic variation occurred within single colonies, and the relationships between clumps indicated that they were dispersed down small meltwater drainage channels by water. The genetic similarities between Arrival Heights colonies and others from Scott Base and Crater Hill a few kilometres away, together with the prevailing wind direction and absence of this moss in the intervening snow-covered area, suggested longer distance dispersal by wind. Overall, the Ross Island samples appeared to form a single polymorphic population distinct from another population at Canada Glacier, 110 km away. Somatic mutation, rather than immigration of genetically different propagules from elsewhere, appeared the most likely cause of genetic variability in these haploid, vegetatively-reproducing Antarctic moss populations. Initiation of recolonisation of Sarconeurum glaciale across a dirt track at Arrival Heights was also investigated by RAPDs, to investigate how regrowth of mosses in disturbed areas occurs in the extreme environment of Antarctica.