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Dutech, C., Seiter, J., Petronelli, P., Joly, H. I., & Jarne, P. (2002). Evidence of low gene flow in a neotropical clustered tree species in two rainforest stands of French Guiana. Mol. Ecol., 11(4), 725–738.
Abstract: The spatial genetic structure of the neotropical, clustered tree species Vouacapoua americana (Aublet) was studied in two natural forest stands (Paracou and Nouragues) in French Guiana. Using eight microsatellite loci, V. americana is characterized by a marked genetic structure at small spatial distances (under 30-60 m), in agreement with the limited seed dispersal by rodent species. Gene flow through pollen is also shown to be mainly restricted to less than 100 m. This result suggests that most pollination events (mediated through small insects) are probably limited to within-patches of individuals, which might explain the high genetic differentiation among patches (F-ST = 0.11) separated by less than 2 km. We also assume that stronger genetic structure in Paracou is likely to be due to lower seed dispersal by rodents, large spatial distances separating patches, or a recent recolonization event.
Keywords: Caesalpiniaceae; gene flow; recolonization process; spatial genetic structure; tropical rainforest; Vouacapoua americana
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Le Guen, V., Rodier-Goud, M., Troispoux, V., Xiong, T. C., Brottier, P., Billot, C., et al. (2004). Characterization of polymorphic microsatellite markers for Microcyclus ulei, causal, agent of South American leaf blight of rubber trees. Mol. Ecol. Notes, 4(1), 122–124.
Abstract: South American leaf blight caused by the ascomycete Microcyclus Wei is the most harmful disease of the rubber tree in Latin America and a potential threat to Asiatic and African natural rubber production. Until now, the variability of this fungus was assessed through observation of pathogenicity of isolates on a range of rubber tree clones with known resistance reactions. The present study describes the process used to design 11 microsatellite markers and evaluates their usefulness in detecting genetic polymorphism. Nine of these markers were polymorphic among six isolates from Brazil (with two to three alleles per locus) and five markers were polymorphic among four isolates from French Guiana (with two to four alleles per locus).
Keywords: Hevea brasiliensis; Microcyclus ulei; microsatellite markers; phytopathogenic fungi; South American leaf blight
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Charles-Dominique, P., Chave, J., Dubois, M. A., De Granville, J. J., Riera, B., & Vezzoli, C. (2003). Colonization front of the understorey palm Astrocaryum sciophilum in a pristine rain forest of French Guiana. Glob. Ecol. Biogeogr., 12(3), 237–248.
Abstract: Aims Astrocaryum sciophilum (Miq.) Pulle (Arecaceae) is an understorey palm, endemic to north-eastern South America with a patchy distribution. We tested the hypothesis that the spatial distribution of this palm species is not in equilibrium but is slowly colonizing the forest understorey. Location Inventories and seed dispersal studies were conducted in the undisturbed tropical forest close to the Nouragues research station, French Guiana. Additional data were collected in the entire territory of French Guiana. Methods We studied the demography of A. sciophilum on a 20-ha plot located at the edge of its distribution. The age of the palms was estimated by postulating an exponentially decreasing abundance by age class. Direct seed dispersal experiments were also conducted, to estimate dispersal parameters. The seeds of A. sciophilum were dispersed only by rodents. This information was used to parameterize a forest growth simulator, to study the spatial spread of this species. Results Within the sampling plot, the density of A. sciophilum dropped sharply from about 500 individuals per hectare to zero. The maturation age was estimated to be 170+/-70 years, and over 55 years with 95% confidence. Seed-dispersal experiments yielded an average seed dispersal distance of 11 m and a maximum estimated dispersal distance of 125 m across a generational span of 55 years to maturity. Therefore, the maximal estimated colonization speed is 2.3 m/y. Conclusions Empirical results and numerical simulations suggest that the boundary of the A. sciophilum population is a colonization front, and that the range of this species is slowly expanding. The implications of this result in respect of palaeoenvironmental changes in this region are discussed.
Keywords: Astrocaryum sciophilum; French Guiana; neotropical palaeoecology; palm ecology; population edge; refuges; scatter-hoarding; seed dispersal; spatial pattern
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Malé, P. - J. G., Bardon, L., Besnard, G., Coissac, E., Delsuc, F., Engel, J., et al. (2014). Genome skimming by shotgun sequencing helps resolve the phylogeny of a pantropical tree family. Mol. Ecol. Resour., 14(5), 966–975.
Abstract: Whole genome sequencing is helping generate robust phylogenetic hypotheses for a range of taxonomic groups that were previously recalcitrant to classical molecular phylogenetic approaches. As a case study, we performed a shallow shotgun sequencing of eight species in the tropical tree family Chrysobalanaceae to retrieve large fragments of high-copy number DNA regions and test the potential of these regions for phylogeny reconstruction. We were able to assemble the nuclear ribosomal cluster (nrDNA), the complete plastid genome (ptDNA) and a large fraction of the mitochondrial genome (mtDNA) with approximately 1000×, 450× and 120× sequencing depth respectively. The phylogenetic tree obtained with ptDNA resolved five of the seven internal nodes. In contrast, the tree obtained with mtDNA and nrDNA data were largely unresolved. This study demonstrates that genome skimming is a cost-effective approach and shows potential in plant molecular systematics within Chrysobalanaceae and other under-studied groups. © 2014 John Wiley & Sons Ltd.
Keywords: Next-generation sequencing; Organellar genome; Phylogenomics; Tropical trees
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Carrias, J. - F., Céréghino, R., Brouard, O., Pélozuelo, L., Dejean, A., Couté, A., et al. (2014). Two coexisting tank bromeliads host distinct algal communities on a tropical inselberg. Plant Biol., 16(5), 997–1004.
Abstract: The tank bromeliads Aechmea aquilega (Salisb.) and Catopsis berteroniana (Schultes f.) coexist on a sun-exposed Neotropical inselberg in French Guiana, where they permit conspicuous freshwater pools to form that differ in size, complexity and detritus content. We sampled the algal communities (both eukaryotic and cyanobacterial taxa, including colourless forms) inhabiting either A. aquilega (n = 31) or C. berteroniana (n = 30) and examined differences in community composition and biomass patterns in relation to several biotic and abiotic variables. Chlorella sp. and Bumilleriopsis sp. were the most common taxa and dominated the algal biomass in A. aquilega and C. berteroniana, respectively. Using a redundancy analysis, we found that water volume, habitat complexity and the density of phagotrophic protozoa and collector-gatherer invertebrates were the main factors explaining the distribution of the algal taxa among the samples. Hierarchical clustering procedures based on abundance and presence/absence data clearly segregated the samples according to bromeliad species, revealing that the algal communities in the smaller bromeliad species were not a subset of the communities found in the larger bromeliad species. We conclude that, even though two coexisting tank bromeliad populations create adjacent aquatic habitats, each population hosts a distinct algal community. Hence, bromeliad diversity is thought to promote the local diversity of freshwater algae in the Neotropics. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.
Keywords: Algae; Bromeliaceae; Inselberg; Neotropics; Phytotelmata; Aechmea; algae; Bromeliaceae; Bumilleriopsis; Catopsis berteroniana; Chlorella (unclassified Chlorophyceae); Chlorella (unclassified Trebouxiophyceae); Chlorella sp.; Cyanobacteria; Eukaryota; Invertebrata; Protozoa
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Denis, T., Hérault, B., Brunaux, O., Guitet, S., & Richard-Hansen, C. (2018). Weak environmental controls on the composition and diversity of medium and large-sized vertebrate assemblages in neotropical rain forests of the Guiana Shield. Diversity Distrib., 24(11), 1545–1559.
Abstract: Aim: Despite their often high-trophic position and their contribution to many ecosystem functions, little is known about the factors affecting assemblage structure of medium- and large-sized neotropical vertebrates. We examined the relative roles played by the physical and biological environment, and by purely spatial processes, in shaping the composition and diversities of these vertebrate assemblages. Then, based on the theory that the Guianan forest cover shrank to isolated pockets during the late Pleistocene–Holocene, we tested if the past forest refugia may have shaped current vertebrate assemblages. Location: French Guiana, Guiana Shield, South America. Methods: Abundances of 19 medium- and large-sized vertebrates were estimated at 21 locations in undisturbed Guianan rain forests. Using taxonomic, functional and phylogenetic metrics, we partitioned the effects of a range of physical and biological environmental conditions and purely spatial predictors in shaping both assemblage composition and (alpha and beta) diversities. Results: We identified a significant, but weak relationship between taxonomic, functional and phylogenetic assemblage composition and environmental conditions. Assemblage diversity patterns were mainly explained by spatial predictors irrespective of the metrics. Current assemblage diversities are correlated with Pleistocene–Holocene forest history, with the highest alpha diversities outside of putative forest refugia, and the highest beta diversities inside these areas. Main conclusions: Current vertebrate assemblage composition is not strongly marked by common environmental factors. Our main conclusion is that assemblage composition results from individual species responses to the environment. Our findings also suggest that dispersal-related processes or more probably historical processes shape (alpha and beta) diversity patterns. In fact, forest fragmentation during Pleistocene–Holocene climate changes could have led to isolated vertebrate assemblages evolving into unique species assemblages creating the current high beta diversity inside refugia, whereas the lower habitat stability outside of refugia could have led to mixed assemblages in areas recolonized by forest vertebrates (current high alpha diversity outside of refugia).
Keywords: biodiversity; birds; functional traits; mammals; refugia hypothesis; spatial patterns; Aves; Mammalia; Vertebrata
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Santiago, L. S., De Guzman, M. E., Baraloto, C., Vogenberg, J. E., Brodie, M., Hérault, B., et al. (2018). Coordination and trade-offs among hydraulic safety, efficiency and drought avoidance traits in Amazonian rainforest canopy tree species. New Phytol., 218(3), 1015–1024.
Abstract: Predicting responses of tropical forests to climate change-type drought is challenging because of high species diversity. Detailed characterization of tropical tree hydraulic physiology is necessary to evaluate community drought vulnerability and improve model parameterization. Here, we measured xylem hydraulic conductivity (hydraulic efficiency), xylem vulnerability curves (hydraulic safety), sapwood pressure–volume curves (drought avoidance) and wood density on emergent branches of 14 common species of Eastern Amazonian canopy trees in Paracou, French Guiana across species with the densest and lightest wood in the plot. Our objectives were to evaluate relationships among hydraulic traits to identify strategies and test the ability of easy-to-measure traits as proxies for hard-to-measure hydraulic traits. Xylem efficiency was related to capacitance, sapwood water content and turgor loss point, and other drought avoidance traits, but not to xylem safety (P50). Wood density was correlated (r = −0.57 to −0.97) with sapwood pressure–volume traits, forming an axis of hydraulic strategy variation. In contrast to drier sites where hydraulic safety plays a greater role, tropical trees in this humid tropical site varied along an axis with low wood density, high xylem efficiency and high capacitance at one end of the spectrum, and high wood density and low turgor loss point at the other.
Keywords: Amazonian forest; cavitation; drought; hydraulic conductivity; sapwood capacitance; turgor loss point; wood density; xylem; cavitation; climate change; drought; forest canopy; forest ecosystem; hydraulic conductivity; rainforest; species diversity; tree; tropical forest; vulnerability; wood; Amazonia; French Guiana; Paracou
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Esquivel-Muelbert, A., Baker, T. R., Dexter, K. G., Lewis, S. L., Brienen, R. J. W., Feldpausch, T. R., et al. (2019). Compositional response of Amazon forests to climate change. Global Change Biol., 25(1), 39–56.
Abstract: Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate-induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long-term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO 2 concentrations): maximum tree size, biogeographic water-deficit affiliation and wood density. Tree communities have become increasingly dominated by large-statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry-affiliated genera have become more abundant, while the mortality of wet-affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry-affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate-change drivers, but yet to significantly impact whole-community composition. The Amazon observational record suggests that the increase in atmospheric CO 2 is driving a shift within tree communities to large-statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.
Keywords: bioclimatic niches; climate change; compositional shifts; functional traits; temporal trends; tropical forests; bioclimatology; climate change; floristics; lowland environment; niche; temporal variation; tropical forest; Amazonia; carbon dioxide; water; biodiversity; Brazil; classification; climate change; ecosystem; forest; physiology; season; tree; tropic climate; Biodiversity; Brazil; Carbon Dioxide; Climate Change; Ecosystem; Forests; Seasons; Trees; Tropical Climate; Water
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Kattge, J., Bönisch, G., Díaz, S., Lavorel, S., Prentice, I. C., Leadley, P., et al. (2020). TRY plant trait database – enhanced coverage and open access. Global Change Biol., 26(1), 119–188.
Abstract: Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
Keywords: data coverage; data integration; data representativeness; functional diversity; plant traits; TRY plant trait database; biodiversity; data processing; database; ecological modeling; environmental factor; growth; intraspecific competition; access to information; biodiversity; ecology; ecosystem; plant; Access to Information; Biodiversity; Ecology; Ecosystem; Plants
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Legeay, J., Husson, C., Boudier, B., Louisanna, E., Baraloto, C., Schimann, H., et al. (2020). Surprising low diversity of the plant pathogen Phytophthora in Amazonian forests. Environ. Microbiol., 22(12), 5019–5032.
Abstract: The genus Phytophthora represents a group of plant pathogens with broad global distribution. The majority of them cause the collar and root-rot of diverse plant species. Little is known about Phytophthora communities in forest ecosystems, especially in the Neotropical forests where natural enemies could maintain the huge plant diversity via negative density dependence. We characterized the diversity of soil-borne Phytophthora communities in the North French Guiana rainforest and investigated how they are structured by host identity and environmental factors. In this little-explored habitat, 250 soil cores were sampled from 10 plots hosting 10 different plant families across three forest environments (Terra Firme, Seasonally Flooded and White Sand). Phytophthora diversity was studied using a baiting approach and metabarcoding (High-Throughput Sequencing) on environmental DNA extracted from both soil samples and baiting-leaves. These three approaches revealed very similar communities, characterized by an unexpected low diversity of Phytophthora species, with the dominance of two cryptic species close to Phytophthora heveae. As expected, the Phytophthora community composition of the French Guiana rainforest was significantly impacted by the host plant family and environment. However, these plant pathogen communities are very small and are dominated by generalist species, questioning their potential roles as drivers of plant diversity in these Amazonian forests. © 2020 Society for Applied Microbiology and John Wiley & Sons Ltd.
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