Biology and population studies of two endemic Nematoceras (orchid) species on sub-Antarctic Macquarie Island

Two endemic orchid species, Nematoceras dienemum and N. sulcatum, are known from sub-Antarctic Macquarie Island. Several additional orchid populations on the island are reported and deistogamy is documented in N. dienemum for the first time. The known population sizes, habitats and locations for both orchid species are documented here, and new information on their biology and population ecology is provided

Measurement of moss growth in continental Antarctica

Using steel pins inserted into growing moss colonies near Casey Station, Wilkes Land, continental Antarctica, we have measured the growth rate of three moss species: Bryum pseudotriquetrum and Schistidium antarctici over 20 years and Ceratodon purpureus over 10 years. This has provided the first long-term growth measurements for plants in Antarctica, confirming that moss shoots grow extremely slowly in Antarctica, elongating between 1 and 5 mm per year. Moss growth rates are dependent on availability of water. Antheridia were observed on some stems of B. pseudotriquetrum; no archegonia or sporophytes were observed. Stems bearing antheridia elongated much more slowly than vegetative stems in the same habitat. Two other methods of growth rate measurement were tested, and gave similar rates of elongation over shorter periods of time. However, for long-term measurements, the steel pin measurements proved remarkably reproducible and reliable

Genetic diversity in the moss Pohlia nutans on geothermal ground of Mount Rittmann, Victoria Land, Antarctica

The only known population of the moss Pohlia nutans in continental Antarctica occurs on geothermally heated ground of volcanic Mt. Rittmann in northern Victoria Land. Colonisation by this bryophyte is due to peculiar environmental characteristics of the geothermal ground, because mosses do not normally grow in Antarctica at such elevations. Specimens from several moss patches within two sites of 80 m2 total area were analysed genetically to determine whether they all originated from a single colonisation event, whether the population is genetically diverse, and whether the temperature range of geothermal ground (17-35°C under moss colonies) affects rates of mutation. Both the RAPD technique and DNA sequencing of the conserved nuclear ribosomal RNA 18S-26S ITS region were used to compare this extremely isolated population with specimens of P. nutans from elsewhere in Antarctica. Like the moss Campylopus pyriformis on volcanic Mt. Melbourne, the Pohlia population exhibits low levels of genetic diversity and appears to be derived from a single immigration event followed by vegetative growth, mutation and dispersal

Mosses Surviving on the Edge: Origins, Genetic Diversity, and Mutation in Antarctica

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New records of three moss species (Ptychostomum pseudotriquetrum, Schistidium antarctici, and Coscinodon lawianus) from the southern Prince Charles Mountains, Mac.Robertson Land, Antarctica

We have used a combination of traditional morphological examination and molecular DNA analysis to characterise 16 moss specimens collected from the Mawson Escarpment and Clemence Massif, exposures of bedrock and glacial debris in the southern Prince Charles Mountains of East Antarctica. The nuclear ribosomal ITS region and the chloroplast rps4 gene were sequenced and compared with those of other mosses known from coastal East Antarctica. The moss specimens from the southern Prince Charles Mountains were identified as Ptychostomum pseudotriquetrum (Hedw.) D. T. Holyoak and N. Pedersen, Schistidium antarctici (Cardot) 'L.I. Savicz & Smirnova' and Coscinodon lawianus (J.H. Willis) Ochyra. These constitute a new record for S. antarctici in the Prince Charles Mountains, and confirm and extend southwards previous records for P. pseudotriquetrum and C. lawianus in the region

Genetic diversity and dispersal of the moss Sarconeurum glaciale on Ross Island, East Antarctica

The extent of genetic variation and dispersal mechanisms were investigated over short distances of 1-100 m, and up to 3 km, by the random amplified polymorphic DNA (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 the colonies from Arrival Heights and others from Scott Base and Crater Hill, a few km 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 that was distinct from another population at Canada Glacier, 110 km distant. Somatic mutation, rather than immigration of genetically different propagules from elsewhere, appeared to be the most probable cause of genetic variability in these haploid, vegetatively reproducing Antarctic moss populations. Initiation of recolonization of S. glaciale across a dirt track at Arrival Heights was also investigated by RAPDs, to investigate how regrowth of mosses in disturbed areas occurred in the extreme environment of Antarctica