From numerous strong candidates in this issue of Journal of Ecology, I have selected a paper by L. J. Clarke, D. J. Ayre and S. A. Robinson, entitled Somatic mutation and the Antarctic ozone hole as my Editor’s Choice. This important contribution starts by referring to the often-repeated claim that exposure to elevated UV-B (UV-BR) radiation as a consequence of stratospheric ozone depletion over Antarctica will increase the rates of somatic mutation in many species. It is expected that the mosses, algae and lichens that grow in Antarctica may be especially at risk, because, unlike vascular species, most of them lack epidermal and cuticular protection against damage from radiation. To test whether mutation rates were higher in the Antarctic than elsewhere, Clarke et al. used microsatellite markers to compare genetic variation in populations of the cosmopolitan moss Ceratodon purpureus collected from continental Antarctica, the sub-Antarctic and temperate regions.
C. purpureus reproduces both sexually and asexually in populations from temperate regions, but sexual reproduction is less common in sub-Antarctic populations, and unknown in continental Antarctica. Sampling procedures therefore had to be designed to minimise any impact on the results due to differences in clonality between populations from different regions. Contrary to expectation, intra-population genetic variation was significantly lower in populations from continental Antarctica than in those from the temperate and sub-Antarctic locations that were studied. These results suggest that, contrary to expectation, the ozone hole has not been associated with elevated mutation rates in continental Antarctica.
Continental Antarctic populations were also strongly genetically isolated compared with temperate populations from Australia and Europe. This finding parallels the results of a number of other investigations. The low diversity of the continental Antarctic moss populations, and their physical isolation from populations that reproduce sexually, may severely limit their capacity to respond adaptively to change in their environment caused, for example, by alterations in climate, and limit their ability to re-colonise sites following local extinction. Even if re-colonisation can occur, slow rates of growth will mean that recovery from damage is likely to be prolonged, given the low growth rates of mosses in the Antarctic. These results reinforce the view that climate change is likely to have dramatic and possibly irreversible effects on the fragile plant communities of continental Antarctica.
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Somatic mutation and the Antarctic ozone hole
Laurence J. Clarke et al.
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