Summary
The moss Hennediella heimii constitutes a significant proportion of the terrestrial flora of East Antarctica, especially in the McMurdo Dry Valleys region of southern Victoria Land. This is the first investigation of the extent of genetic variation within a population of Hennediella heimii. RAPDs (Random Amplified Polymorphic DNA) have been used to study both genetic diversity and dispersal of this moss in Miers Valley, southern Victoria Land. The results showed that genetic variation does occur in Hennediella heimii (possibly due to increased exposure to UV-B irradiation), even between shoots within single colonies, and that colonies collected from three transects, along meltstreams within the valley, comprise a single large population. However, comparison with samples of the same species from nearby valleys and sites up to 500 km distant showed that the Miers Valley population is distinct from others. The results also indicate that wind plays a major role in dispersal of Hennediella heimii in this region of Antarctica.