Abstract: Genetic variation for intrinsic water use efficiency (W-i) and related traits was estimated in a full-sib family of Quercus robur L. over 3 years. The genetic linkage map available for this F1 family was used to locate quantitative trait loci (QTL) for W-i, as estimated by leaf carbon stable isotope composition (delta C-13) or the ratio of net CO2 assimilation rate (A) to stomatal conductance to water vapour (g(w)) and related leaf traits. Gas exchange measurements were used to standardize estimates of A and g(w) and to model the sensitivity of gw to leaf-to-air vapour pressure deficit (sg(VPD)). delta C-13 varied by more than 3% among the siblings, which is equivalent to 40% variation of W-i. Most of the studied traits exhibited high clonal mean repeat-abilities (> 50%; proportion of clonal mean variability in global variance). Repeatabilities for delta C-13, leaf mass per area (LMA) and leaf nitrogen content were higher than 70%. For delta C-13, ten QTLs were detected, one of which was detected repeatedly for all 3 years and consistently explained more than 20% of measured variance. Four genomic regions were found in which co-localizing traits linked variation in W-i to variations in leaf chlorophyll and nitrogen content, LMA and sg(VPD). A positive correlation using clonal means between delta C-13 and A/g(w), as well as a co-localisation of QTL detected for both traits, can be seen as validation of the theoretical model linking the genetic architecture of these two traits.

Abstract: Rivers of French Guiana are still little invaded by non-native fish, but several fish introductions were recently recorded through the development of aquarium fish trade and fish farms. Here we report records of 11 non-native fish species. Among them, four (Cichla monoculus, Heros efasciatus, Mesonauta guyanae and Poecilia reticulata) are established and one of them (Heros efasciatus) is rapidly increasing its spatial range. Two species (Hyphessobrycon eques and Pterophyllum scalare) were not retrieved in recent records and are probably extinct from French Guiana. The establishment status of the five other species (Arapaima gigas, Colossoma macropomum, Cyprinus carpio, Oreochromis mossambicus and Osteoglossum bicirrhosum) is uncertain and only a few specimens were observed in the wild. Nevertheless, these species, intensively reared in nearby countries, belong to highly invasive species able to cause detrimental impacts on recipient ecosystems. Those first occurrences of invasive fish species in French Guiana should therefore act as an early warning for both researchers and environmental managers.

Abstract: We assessed the occurrence of algae in five species of tank-bromeliads found in contrasting environmental sites in a Neotropical, primary rainforest around the Nouragues Research Station, French Guiana. The distributions of both algal abundance and biomass were examined based on physical parameters, the morphological characteristics of bromeliad species and with regard to the structure of other aquatic microbial communities held in the tanks. Algae were retrieved in all of the bromeliad species with mean densities ranging from similar to 10(2) to 10(4) cells/mL. Their biomass was positively correlated to light exposure and bacterial biomass. Algae represented a tiny component of the detrital food web in shaded bromeliads but accounted for up to 30 percent of the living microbial carbon in the tanks of Catopsis berteroniana, located in a highly exposed area. Thus, while nutrient supplies are believed to originate from wind-borne particles and trapped insects (i.e., allochtonous organic matter), our results indicate that primary producers (i.e., autochtonous organic matter) are present in this insectivorous bromeliad. Using a 24-h incubation of size-fractionated and manipulated samples from this plant, we evaluated the impact of mosquito foraging on algae, other microorganisms and rotifers. The prey assemblages were greatly altered by the predation of mosquito larvae. Grazing losses indicated that the dominant algal taxon, Bumilleriopsis sp., like protozoa and rotifers, is a significant part of the diet of mosquito larvae. We conclude that algae are a relevant functional community of the aquatic food web in C. berteroniana and might form the basis of a complementary non-detrital food web.

Abstract: Background: The Amazonian rainforest is predicted to suffer from ongoing environmental changes. Despite the need to evaluate the impact of such changes on tree genetic diversity, we almost entirely lack genomic resources. Results: In this study, we analysed the transcriptome of four tropical tree species (Carapa guianensis, Eperua falcata, Symphonia globulifera and Virola michelii) with contrasting ecological features, belonging to four widespread botanical families (respectively Meliaceae, Fabaceae, Clusiaceae and Myristicaceae). We sequenced cDNA libraries from three organs (leaves, stems, and roots) using 454 pyrosequencing. We have developed an R and bioperl-based bioinformatic procedure for de novo assembly, gene functional annotation and marker discovery. Mismatch identification takes into account single-base quality values as well as the likelihood of false variants as a function of contig depth and number of sequenced chromosomes. Between 17103 (for Symphonia globulifera) and 23390 (for Eperua falcata) contigs were assembled. Organs varied in the numbers of unigenes they apparently express, with higher number in roots. Patterns of gene expression were similar across species, with metabolism of aromatic compounds standing out as an overrepresented gene function. Transcripts corresponding to several gene functions were found to be over- or underrepresented in each organ. We identified between 4434 (for Symphonia globulifera) and 9076 (for Virola surinamensis) well-supported mismatches. The resulting overall mismatch density was comprised between 0.89 (S. globulifera) and 1.05 (V. surinamensis) mismatches/100 bp in variation-containing contigs.Conclusion: The relative representation of gene functions in the four transcriptomes suggests that secondary metabolism may be particularly important in tropical trees. The differential representation of transcripts among tissues suggests differential gene expression, which opens the way to functional studies in these non-model, ecologically important species. We found substantial amounts of mismatches in the four species. These newly identified putative variants are a first step towards acquiring much needed genomic resources for tropical tree species. © 2014 Brousseau et al.; licensee BioMed Central Ltd.

Abstract: In 2002, nearly 200 nations signed up to the 2010 target of the Convention for Biological Diversity, ‘to significantly reduce the rate of biodiversity loss by 2010’. To assess whether the target was met, it became necessary to quantify temporal trends in measures of diversity. This resulted in a marked shift in focus for biodiversity measurement. We explore the developments in measuring biodiversity that was prompted by the 2010 target. We consider measures based on species proportions, and also explain why a geometric mean of relative abundance estimates was preferred to such measures for assessing progress towards the target. We look at the use of diversity profiles, and consider how species similarity can be incorporated into diversity measures. We also discuss measures of turnover that can be used to quantify shifts in community composition arising, for example, from climate change. © 2017, The Author(s).