Enhanced sexual reproduction in bryophytes at high latitudes in the maritime Antarctic

Contrary to the generally accepted hypothesis that bryophyte fertility decreases with increasing latitude and therefore climatic severity, a detailed study of bryophyte reproductive strategies at sites in the southern maritime Antarctic (68–72°S) has revealed that an unexpectedly high proportion of species is capable of producing sporophytes. Of the regional bryoflora, 43% (19 species; 17 mosses, 2 liverworts) in Marguerite Bay and 47% (17 species; 16 mosses, 1 liverwort) in Alexander Island are known to produce sporophytes, although the number fruiting at comparable latitudes on the colder and more arid Antarctic continent is less (33%). These numbers and proportions are much greater than were previously known at such relatively high southern polar latitudes. Sporophytes of several species are recorded for the first time within the Antarctic biome, while those of two liverworts (Lophozia excisa and Cephaloziella varians) are reported for the first time south of 62°S. High incidence of sporophyte production is attributed to locally favourable microclimatic conditions producing small-scale 'oases'. The large majority of fertile mosses are monoecious short acrocarps growing on rather calcareous soils. Spore production and size data for a number of species are compared with previously published studies of the same or closely related species from the northern maritime Antarctic and sub-Antarctic, but no consistent trends are revealed between species over the latitudinal gradient.