Integrated taxonomy combining morphological and molecular biological analyses of soil nematodes from maritime Antarctica

Abstract

Nematodes are one of the key organisms in the terrestrial ecosystems of Antarctica. Their exceptional cryptobiotic adaptations against freezing and desiccation stress have attracted significant research attention. However, even today, relatively little is known about the biology of nematodes across this continent, especially in terms of their biodiversity and distribution. To address such fundamental research areas, correct classification of Antarctic nematodes is a necessary underpinning. Until recently, morphological examination has been the only established method available, and this remains challenging even for experts. Advances in molecular biological techniques now provide a complementary approach to nematode classification, but as yet have largely not been applied to the Antarctic fauna. In this study we initiate development of cataloguing of Antarctic nematodes using both morphological and molecular information from individual worms. We collected nematode samples from islands in maritime Antarctica (Signy, Adelaide and Leonie Islands; a latitudinal range between the South Orkney Islands and Marguerite Bay), and classified them by DNA sequence obtained from morphologically-determined samples. We obtained small subunit ribosomal RNA gene (SSU rDNA) sequence data from seven major maritime Antarctic nematode species, which will permit future identification of these species without the requirement for detailed morphological taxonomic analyses. We also trialled the application of molecular analyses to morphologically unidentified samples from King George Island, thereby obtaining support for our approach through the identification of samples with identical sequences. This approach provides baseline information for future studies of Antarctic nematodes.