| Summary: | With over 850 described species, amphipods are by far the most speciose animal group in the Southern Ocean, being present at all depths and occupying a wide range of habitats and trophic niches. At the RBINS, an integrative approach combining morphological and genetic studies is used for studying their species diversity, present-day distributions and for understanding the underlying processes structuring the diversity and the mechanisms of speciation. Both morphological and molecular studies revealed a large number of inadequately or undescribed species in several amphipod groups. DNA taxonomy and phylogeographic studies were conducted to detect possible cryptic diversity and to test the circumpolarity and/or eurybathy of some taxa. These studies demonstrated that several morphospecies are genetically heterogeneous species complexes with allo- and sympatric distributions. Furthermore, molecular phylogenies are applied to test the hypotheses concerning the colonization of the abyssal basins from the shelf and vice versa (the submergence and emergence hypotheses). To expand our knowledge on the processes structuring the Southern Ocean benthos and on predicting their response to environmental changes, future projects will include molecular studies at a microevolutionary scale and the modeling of the spatial distribution of amphipod taxa.
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