Abstract: Anoxygenic phototrophic bacteria (APB) are a very significant metabolic functional group in the phytotelmata of tank-forming Bromeliaceae plants. Considering the close relationships existing between the bromeliad and its tank microbiota, the dominance of APB raises the question of their role in the ecology and evolution of these plants. Here, using pufM gene sequencing for taxonomic profiling, we investigated the structure of APB communities in the tanks of five bromeliad species exhibiting different habitat characteristics (i.e. physicochemical factors associated with the host), and occurring in different localities of French Guiana.
We found that APB assemblages were specific to plant species and were less dependent on location or on bromeliad habitat characteristics. This convergence suggests that the identity of the bromeliad species per se is more important than habitat filtering or dispersal to control specific assembly rules for APB. The pufM OTUs were affiliated with five orders of Alpha- and Beta-proteobacteria (Rhodobacterales, Sphingomonadales, Rhizobiales, Burkholderiales and Rhodospirillales), and we assume that they may be major components of the core microbiota of plant-held waters. Our findings also revealed that up to 79% of the sequences were affiliated with APB clades possessing nitrogen-fixing genes suggesting that this metabolic capability is widespread within the APB community inhabiting tank bromeliads. We hypothesized that bromeliads may benefit nutritionally from associations with free-living APB capable to fix atmospheric nitrogen. Synthesis. Understanding the dominance of APB in tank bromeliads and determining whether a potential interplay exists between these partners is an intriguing aspect of possible mutualistic and coevolving interactions between the two existing forms of chlorophototrophy (i.e. bacteriochlorophyll-based anoxygenic and chlorophyll-based oxygenic phototrophy). In the present study, we found that bromeliad species was the main factor that explained variance in APB community composition. These findings suggest that APB and tank bromeliads may have a close, mutualistic relationship and we hypothesize according to our genomic analyses that APB may promote the bromeliad growth by provisioning essential nutrients like nitrogen.

Abstract: Taccarum ulei (Araceae, Spathicarpeae) is a seasonal geophytic aroid, native to north-eastern Brazil, that flowers during two months of the rainy season. Patterns of floral thermogenesis, pollination biology, and floral traits associated with pollination syndromes were studied and compared with those of other Araceae. Two species of cyclocephaline scarabs (Scarabaeidae, Cyclocephalini) were recognized as effective pollinators: Cyclocephala celata and Cyclocephala cearae. Larvae of an unidentified species of fruit fly (Melanolomaspp., Richardiidae, Diptera) were also frequently observed in inflorescences at various maturation stages, feeding on the connectives of male florets and fruits, and thus lowering the reproductive success of individual plants. Beetles were attracted by odoriferous inflorescences in the early evening of the first day of anthesis, during the female phase. The emission of attractive volatiles was coupled with intense thermogenic activity in the entire spadix, unlike other aroids in which only certain zones of the spadix heat up. Pollen release, which marks the beginning of the male phase on the subsequent evening, was not related to floral thermogenesis. Comparative multivariate analysis of the floral traits of T.ulei points to a beetle-pollinated aroid, although some of the observed traits of the species are not common to other taxa sharing this pollination strategy. Such incongruence might be explained by the evolutionary history of the tribe Spathicarpeae and potential pollinator shifts. © 2012 The Linnean Society of London.

Abstract: Disentangling the impact of landscape features such as rivers and historical events on dispersal is a challenging but necessary task to gain a comprehensive picture of the evolution of diverse biota such as that found in Amazonia. Adenomera andreae, a small, territorial, terrestrial frog species of the Amazonian forest represents a good model for such studies. We combined cytochromeb sequences with 12 microsatellites to investigate the genetic structure at two contrasted spatial scales in French Guiana: along a ∼6-km transect, to evaluate dispersal ability, and between paired bank populations along a ∼65-km stretch of the Approuague river, to test the effect of rivers as barriers to dispersal. We observed significant spatial genetic structure between individuals at a remarkably small geographical scale, and conclude that the species has a restricted dispersal ability that is probably tied to its life-history traits. Mitochondrial and microsatellite data also indicate a high level of differentiation among populations on opposite banks of the river, and, in some cases, among populations on the same riverbank. These results suggest that the observed population structure in A.andreae is the result of restricted dispersal abilities combined with the action of rivers and Quaternary population isolation. Given that Amazonia hosts a great portion of anurans, as well as other small vertebrates, that display life-history traits comparable with A.andreae, we argue that our analyses provide new insights into the complex interactions among evolutionary processes shaping Amazonian biodiversity. © 2012 The Linnean Society of London.

Abstract: Electroactive biofilms were formed from French Guiana mangrove sediments for the analysis of bacterial communities' composition. The electrochemical monitoring of three biofilm generations revealed that the bacterial selection occurring at the anode, supposedly leading microbial electrochemical systems (MESs) to be more efficient, was not the only parameter to be taken into account so as to get the best electrical performance (maximum current density). Indeed, first biofilm generations produced a stable current density reaching about 18A/m2 while second and third generations produced current densities of about 10A/m2. MES bacterial consortia were characterized thanks to molecular biology techniques: DGGE and MiSeq® sequencing (Illumina®). High-throughput sequencing data statistical analysis confirmed preliminary DGGE data analysis, showing strong similarities between electroactive biofilms of second and third generations, but also revealing both selection and stabilization of the biofilms. © 2015 Elsevier B.V.