title: Hologenome theory supported by cooccurrence networks of species-specific bacterial communities in siphonous algae (Caulerpa).
abstract: The siphonous algae of the Caulerpa genus harbor internal microbial communities hypothesized to play important roles in development, defense and metabolic activities of the host. Here, we characterize the endophytic bacterial community of four Caulerpa taxa in the Mediterranean Sea, through 16S rRNA amplicon sequencing. Results reveal a striking alpha diversity of the bacterial communities, similar to levels found in sponges and coral holobionts. These comprise (1) a very small core community shared across all hosts (< 1% of the total community), (2) a variable portion (ca. 25%) shared by some Caulerpa taxa but not by all, which might represent environmentally acquired bacteria and (3) a large (>70%) species-specific fraction of the community, forming very specific clusters revealed by modularity in networks of cooccurrence, even in areas where distinct Caulerpa taxa occurred in sympatry. Indirect inferences based on sequence homology suggest that these communities may play an important role in the metabolism of their host, in particular on their ability to grow on anoxic sediment. These findings support the hologenome theory and the need for a holistic framework in ecological and evolutionary studies of these holobionts that frequently become invasive.
authors.affiliation: CCMAR, Centre of Marine Sciences, University of Algarve, Gambelas, 8005-139 Faro, Portugal.
authors.forename: Tania
authors.initials: T
authors.lastname: Aires
authors.affiliation: IFREMER- Technopole de Brest-Iroise, BP 70, 29280 Plouzané, France UMR 6197-Laboratoire de Microbiologie des Environnements Extrêmes, Université de Bretagne Occidentale (UBO) Institut Universitaire Européen de la Mer (IUEM), CNRS, Plouzané, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Moalic
authors.affiliation: CCMAR, Centre of Marine Sciences, University of Algarve, Gambelas, 8005-139 Faro, Portugal.
authors.forename: Ester A
authors.initials: EA
authors.lastname: Serrao
authors.affiliation: CCMAR, Centre of Marine Sciences, University of Algarve, Gambelas, 8005-139 Faro, Portugal UMR MARBEC (Marine Biodiversity, Exploitation and Conservation) Bd Jean Monnet, BP 171, 34203 Sète Cedex - France sarnaud@ifremer.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Arnaud-Haond
mesh_terms: D000818:Animals; D037421:Anthozoa; D001419:Bacteria / Q000235:genetics*; D044822:Biodiversity; D046068:Caulerpa / Q000235:genetics / Q000382:microbiology*; D060026:Endophytes / Q000235:genetics*; D008522:Mediterranean Sea; D059013:Microbial Consortia / Q000235:genetics*; D010944:Plants; D011161:Porifera / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013045:Species Specificity
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: bacterial community; coevolution; cooccurrence network; endophytic bacteria; modularity