| Summary: | participant Many features already show how Polar seas are impacted by present-day global warming. To cope with new climate-induced changes and survive, Antarctic and Subantarctic marine organisms can either migrate or adapt to new prevailing conditions. New biotic interactions between Southernmost species and Subantarctic invaders can be expected, as new biogeographical distributions have already been documented. Because they are biologically and ecologically well diversified, echinoids play an important part in Antarctic benthic communities. Moreover, symbioses associated to cidarid echinoids make them even more crucial for benthic diversity. The biogeographical mapping of Antarctic echinoids (south of latitude 35° S) is being performed using both data from literature and new records from the numerous recent cruise campaigns around Antarctica. The second step and objective of our work is to identify and characterize the main factors that control echinoid distribution in the Antarctic. To obtain a comprehensive model of echinoid biogeographical and macroecological patterns, physical data are matched to echinoid distribution using GIS. Two alternative hypotheses will be tested: (1) is Antarctic echinoid distribution controlled by environmental and physical factors such as water temperature, sediments and depth (the environmental hypothesis) or (2) is echinoid distribution best explained by historical biogeography (the provincialist hypothesis)?
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