title: Cave microbial community composition in oceanic islands: disentangling the effect of different colored mats in diversity patterns of Azorean lava caves.
abstract: Processes determining diversity and composition of bacterial communities in island volcanic caves are still poorly understood. Here, we characterized colored microbial mats in 14 volcanic caves from two oceanic islands of the Azores using 16S rRNA gene sequences. Factors determining community diversity (α) and composition (β) were explored, namely colored mats, caves and islands, as well as environmental and chemical characteristics of caves. Additive partitioning of diversity using OTU occurrence showed a greater influence of β-diversity between islands and caves that may relate to differences in rare OTUs (singletons and doubletons) across scales. In contrast, Shannon diversity partitioning revealed the importance of the lowest hierarchical level (α diversity, colored mat), suggesting a dominance of cosmopolitan OTUs (>1%) in most samples. Cosmopolitan OTUs included members involved in nitrogen cycling, supporting the importance of this process in Azorean caves. Environmental and chemical conditions in caves did not show any significant relationship to OTU diversity and composition. The absence of clear differences between mat colors and across scales may be explained by (1) the geological youth of the cave system (cave communities have not had enough time to diverge) or/and (2) community convergence, as the result of selection pressure in extreme environments.
authors.affiliation: Food Science and Health Group (CITA-A), Universidade dos Açores, Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Riquelme
authors.affiliation: cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal Environment and Microbiology Team, MELODY group, Université of Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013 Pau Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Rigal
authors.affiliation: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Jennifer J M
authors.initials: JJ
authors.lastname: Hathaway
authors.affiliation: Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Diana E
authors.initials: DE
authors.lastname: Northup
authors.affiliation: Institute of Meteoritics, MSC03 2050, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Spilde
authors.affiliation: cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.
authors.forename: Paulo A V
authors.initials: PA
authors.lastname: Borges
authors.affiliation: cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.
authors.forename: Rosalina
authors.initials: R
authors.lastname: Gabriel
authors.affiliation: cE3c - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group and Universidade dos Açores - Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.
authors.forename: Isabel R
authors.initials: IR
authors.lastname: Amorim
authors.affiliation: Food Science and Health Group (CITA-A), Universidade dos Açores, Departamento de Ciências Agrárias, Rua Capitão João d'Ávila, São Pedro, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal mariaenes@uac.pt.
authors.forename: Maria de Lurdes N E
authors.initials: Mde L
authors.lastname: Dapkevicius
mesh_terms: D001394:Azores; D001483:Base Sequence; D044822:Biodiversity; D059552:Caves / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D062312:Islands; D059013:Microbial Consortia / Q000235:genetics*; D010944:Plants / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: Azores; additive partitioning; bacterial diversity; lava cave; levels of organization; sampling grain