Evolutionary pathways among shallow and deep-sea echinoids of the genus Sterechinus in the Southern Ocean.

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Díaz, Angie, Féral, Jean-Pierre, David, Bruno, Saucède, Thomas, Poulin, Elie
• Other Authors: Instituto de Ecología y Biodiversidad (IEB), Diversité, évolution et écologie fonctionnelle marine (DIMAR), Université de la Méditerranée - Aix-Marseille 2-Centre National de la Recherche Scientifique (CNRS), Biogéosciences UMR 6282 (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Study supported by the Grants INACH D 05-09, Conicyt Ph.D. Grant no D-21080136, and by the projects P05-002 ICM and PFB 023 (Institute of Ecology and Biodiversity, Universidad de Chile) and INACH 02-02, 13-05 and ECOS C06B02., ANR-07-BLAN-0213,ANTFLOCKS,ANTARCTIC SHELF AS A SPECIES FLOCKS GENERATOR(2007)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: Sea urchins; Coastal zone; Deep water; Phylogeny; Biogeography; Evolutionary patterns; COI; [SDV.BID.SPT]Life Sciences [q-bio]/Biodiversity/Systematics; Phylogenetics and taxonomy; Antarctic; Argentina; Kerguelen; Southern Ocean; Weddell; Antarc*; Antarctica; antarcticus
• Online Access: https://hal.archives-ouvertes.fr/hal-00567501; https://hal.archives-ouvertes.fr/hal-00567501/document; https://hal.archives-ouvertes.fr/hal-00567501/file/2011_Diaz_Deep%20Sea%20Res.%20II_pr_Evolutionary%20pathways%20among%20shallow%20and%20deep-sea%20echinoids%20of%20the%20genus%20Sterechinus%20in%20the%20Southern%20Ocean.pdf; https://doi.org/10.1016/j.dsr2.2010.10.012

7 pages International audience Antarctica is structured by a narrow and deep continental shelf that sustains a remarkable number of benthic species. The origin of these species and their affinities with the deep-sea fauna that borders the continent shelf are not clear. To date, two main hypotheses have been considered to account for the evolutionary connection between the faunas: (1) either shallow taxa moved down to deep waters (submergence) or (2) deep-sea taxa colonized the continental shelf (emergence). The regular sea urchin genus Sterechinus is a good model to explore the evolutionary relationships among these faunas because its five nominal species include Antarctic and Subantarctic distributions and different bathymetric ranges. Phylogenetic relationships and divergence times among Sterechinus species were established using the COI mitochondrial gene by assuming a molecular clock hypothesis. The results showed the existence of two genetically distinct main groups. The first corresponds exclusively to the shallow-water Antarctic species S. neumayeri, while the second includes all the other nominal species, either deep or shallow, Antarctic or Subantarctic. Within the latter group, S. dentifer specimens all formed a monophyletic cluster, slightly divergent from all other specimens, which were mixed in a second cluster that included S. agassizi from the continental shelf of Argentina, S. diadema from the Kerguelen Plateau and S. antarcticus from the deep Antarctic shelf. These results suggest that the deeper-water species S. dentifer and S. antarcticus are more closely related to Subantarctic species than to the shallow Antarctic species S. neumayeri. Thus, for this genus, neither the submergence nor emergence scenario explains the relationships between Antarctic and deep-sea benthos. At least in the Weddell quadrant, the observed genetic pattern suggests an initial separation between Antarctic and Subantarctic shallow species, and a much later colonization of deep water from the Subantarctic region, ...