Declines in both redundant and trace species characterize the latitudinal diversity gradient in tintinnid ciliates

• Published in: The ISME Journal
• Main Authors: Dolan, John R, Yang, Eun Jin, Kang, Sung-Ho, Rhee, Tae Siek
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Korea Polar Research Institute (KOPRI)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDV.BID]Life Sciences [q-bio]/Biodiversity; Arctic
• Online Access: https://hal.sorbonne-universite.fr/hal-01401540; https://hal.sorbonne-universite.fr/hal-01401540/document; https://hal.sorbonne-universite.fr/hal-01401540/file/Dolan_2016_Declines_in_both.pdf; https://doi.org/10.1038/ismej.2016.19

International audience The latitudinal diversity gradient is a well-known biogeographic pattern. However, rarely considered is how a cline in species richness may be reflected in the characteristics of species assemblages. Fewer species may equal fewer distinct ecological types, or declines in redundancy (species functionally similar to one another) or fewer trace species, those occurring in very low concentrations. We focused on tintinnid ciliates of the microzooplankton in which the ciliate cell is housed inside a species-specific lorica or shell. The size of lorica oral aperture, the lorica oral diameter (LOD), is correlated with a preferred prey size and maximum growth rate. Consequently, species of a distinct LOD are distinct in key ecologic characteristics, whereas those of a similar LOD are functionally similar or redundant species. We sampled from East Sea/Sea of Japan to the High Arctic Sea. We determined abundance distributions of biological species and also ecological types by grouping species in LOD size-classes, sets of ecologically similar species. In lower latitudes there are more trace species, more size-classes and the dominant species are accompanied by many apparently ecologically similar species, presumably able to replace the dominant species, at least with regard to the size of prey exploited. Such redundancy appears to decline markedly with latitude in assemblages of tintinnid ciliates. Furthermore, the relatively small species pools of the northern high latitude assemblages suggest a low capacity to adapt to changing conditions.