Title: Early stages in speciation by depth isolation in deep-sea Arctic echinoderms
The goal of this project was to analyze depth related trends in morphological variability and speciation in Arctic deep-sea echinoderms.
Holothuriodea: Material from most of the deep-sea Arctic expeditions over the past 100 years was analyzed including more than two thousand specimens from 141 stations ranging in depth from 70 to 4380 m. Three of the four species recorded for the Arctic basins were found. One species found was new to science and was published in 2007 in Marine Biology Research 3:367-396. Elpidiids from the deeper parts of the Arctic Ocean, determined previously as Elpidia glacialis were identified as Elpidia heckeri or Elpidia belyaevi sp. nov. The figure illustrates the suggested pathways of penetrations and dispersal of the genus Elpidia in the Arctic.
Criniodea: Analyzed material included 155 specimens from 29 stations taken throughout the Arctic Basin from Greenland-Iceland-Faeroe Ridge to the Chukchi Sea, at depths from 460 to 3800 m. Variability in the morphology of Bathycrinus carpenteri was found high, but was no obviously related to depth. A single specimen from >3000m differed from all other specimens by having more elongated stalk segments. Results are being prepared for publication.
Echiniodea: In the genus Echinus, 69 samples from Arctic and North-East Atlantic from the collection of the P.P. Shirshov Institute of Oceanology were examined. This material included 125 specimens representing 7 species. Body size decreased with depth. The diameter of the apical complex increased with depth both between species and between deeper and shallower populations of the same species. Depth-related increases were also seen in the ratio of interambulactral to ambulacral plates and the number of secondary tubercules per coronal aboral plate and the number of lateral teeth on globifer pedicellaria. Spines on buccal and periproct plates tended to disappear. The subspecies Pourtalesia jeffreysi gibbosa and P. jeffreysi lata were compared based on 195 specimens taken at 20 stations from the Norwegian Sea to the Chukchi Sea, at depths from 230 to 3081 m. Results are being prepared for publication.