This applies both to organisms not previously present anywhere in the Antarctic region, and to those whose occurrence or southern distributional limit already lie
within the region. However, because of the severity of Antarctic terrestrial ecosystems, if organisms are to become established beyond their current range, they require tolerance physiology beyond that which is necessary in their native climate. Such organisms are said to be “pre-adapted”. There have been eight known establishment events in the maritime Antarctic to date (Hughes and Convey, 2012). These include the Collembola, Folsomia candida and Protaphorura sp., on Deception Island, the transfer of the collembolan, Hypogastrura viatica, onto the South Shetland Daporinad molecular weight and Léonie Islands, and the introduction of the enchytraeid worm, Christensenidrilus blocki, and the chironomid, E. murphyi, on Signy Island. Further species of Collembola have recently been recorded Forskolin ic50 from Deception Island (Greenslade et al., in review). As with the non-native species (>200) known from the sub-Antarctic islands, these organisms may have significant impacts on the native ecosystems ( Frenot et al., 2005). H.
viatica is described as an aggressive invader on South Georgia and Macquarie Islands ( Frenot et al., 2005 and Tin et al., 2009). Likewise, E. murphyi has been shown by Hughes et al. (in review) as potentially contributing more to Thiamet G nutrient cycling on Signy Island than by that of all the native invertebrates combined. It is therefore important to gain an insight into the pre-adaptation of such organisms if a full
understanding of their establishment and impact, as well as the potential establishment and impact of other organisms, is to be realized. Although this study centres on the RCH response of E. murphyi, the data obtained also confirm that both juvenile and mature larvae possess a marked basal cold tolerance ( Worland, 2010). In both larval groups, the DTemp and the LLT fell below −11.5 and −13 °C, respectively. This, in itself, is a good example of their pre-adaptation, as temperatures rarely, if ever, reach −10 °C in summer ( Davey et al., 1992). Similarly, summer acclimatised larvae of the only other flightless midge of the maritime Antarctic, B. antarctica, showed 95% survival after 24 h at −10 °C, a temperature lower than that which they experience in summer at Palmer Station (64°S 46oW) ( Teets et al., 2008). Our data also indicated a subtle difference in cold tolerance between juvenile and mature larvae. Juveniles were more susceptible at all sub-zero temperatures tested, resulting in an LLT 1 °C higher than that of mature larvae, which survived until −14 °C. Possible explanations include a developmental effect as seen in tardigrades (Hengherr et al.
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