title: Coexisting cryptic species of the Litoditis marina complex (Nematoda) show differential resource use and have distinct microbiomes with high intraspecific variability.
abstract: Differences in resource use or in tolerances to abiotic conditions are often invoked as potential mechanisms underlying the sympatric distribution of cryptic species. Additionally, the microbiome can provide physiological adaptations of the host to environmental conditions. We determined the intra- and interspecific variability of the microbiomes of three cryptic nematode species of the Litoditis marina species complex that co-occur, but show differences in abiotic tolerances. Roche 454 pyrosequencing of the microbial 16S rRNA gene revealed distinct bacterial communities characterized by a substantial diversity (85-513 OTUs) and many rare OTUs. The core microbiome of each species contained only very few OTUs (2-6), and four OTUs were identified as potentially generating tolerance to abiotic conditions. A controlled experiment in which nematodes from two cryptic species (Pm1 and Pm3) were fed with either an E. coli suspension or a bacterial mix was performed, and the 16S rRNA gene was sequenced using the MiSeq technology. OTU richness was 10-fold higher compared to the 454 data set and ranged between 1118 and 7864. This experiment confirmed the existence of species-specific microbiomes, a core microbiome with few OTUs, and high interindividual variability. The offered food source affected the bacterial community and illustrated different feeding behaviour between the cryptic species, with Pm3 exhibiting a higher degree of selective feeding than Pm1. Morphologically similar species belonging to the same feeding guild (bacterivores) can thus have substantial differences in their associated microbiomes and feeding strategy, which in turn may have important ramifications for biodiversity-ecosystem functioning relationships.
authors.affiliation: OD Taxonomy and Phylogeny, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, 1000 Brussels, Belgium.|Department of Biology, Marine Biology Section, Ghent University, Krijgslaan 281 (S8), 9000 Ghent, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Derycke
authors.affiliation: Department of Biology, Marine Biology Section, Ghent University, Krijgslaan 281 (S8), 9000 Ghent, Belgium.|CeMoFE, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: De Meester
authors.affiliation: Department of Biology, Marine Biology Section, Ghent University, Krijgslaan 281 (S8), 9000 Ghent, Belgium.|CeMoFE, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Rigaux
authors.affiliation: Environment Centre Wales Building, School of Biological Sciences, Bangor University, Gwynedd, LL57 2UW, UK.
authors.forename: S
authors.initials: S
authors.lastname: Creer
authors.affiliation: Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY, 10003, USA.
authors.forename: H
authors.initials: H
authors.lastname: Bik
authors.affiliation: Hubbard Center for Genome Studies, University of New Hampshire, 35 Colovos Road, 448 Greg Hall, Durham, NH, 03824, USA.
authors.forename: W K
authors.initials: WK
authors.lastname: Thomas
authors.affiliation: Environment Centre Wales Building, School of Biological Sciences, Bangor University, Gwynedd, LL57 2UW, UK.
authors.forename: T
authors.initials: T
authors.lastname: Moens
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification*; D001530:Belgium; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli; D064307:Microbiota; D009348:Nematoda / Q000145:classification* / Q000382:microbiology*; D009426:Netherlands; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: bacteria; coexistence; diet; individual niche specialization; marine nematodes; next-generation sequencing; resource partitioning; stabilizing effects