An integrated test of Natural-Enemy mediated tree BEta-DIVersity across South American rain forests – NEBEDIV

The project is organized around three series of tasks. The first involves comprehensive sampling of woody plant, insect and soil microbial communities across environmental gradients at the scale of the entire Amazon region. The project will focus on collaborative research in French Guiana, Manaus, Brazil, and Loreto, Peru. Our plot network is unique because it samples a steep environmental gradient represented by nutrient-poor white sand forests and seasonally-inundated forests, in addition to the well-studied terra firme clay forests, within and across the regions of study. This permits an unprecedented examination of tropical species turnover across environmental gradients.
In each region, we have established permanent sampling plots covering 2ha within which we are characterizing woody plant, insect and soil microbe communities using both traditional sampling of vouchers and taxonomic identification, and molecular barcoding via the establishment of associated libraries. Because Phytophthora and Pythium are important plant natural enemies, emphasis was layed upon oomycete diversity in these soils.
The second series of tasks involved host plant-based sampling of trophic interactions with insect herbivores aboveground, and soil microbes below ground. For each of eleven monophyletic host plant lineages spanning the Angiosperm groups, we are sampling insects directly on juvenile trees and soil microbes interacting with roots and rhizospheres, in a subset of about half (48) of our permanent sampling plots. The integration of molecular data for these samples will allow us to test for phylogenetic distance decay in host specialization of both aboveground and below ground associations, and across geographic and environmental gradients.
Finally, in controlled conditions (greenhouse), measurements of the pathogenicity of Phytophthora and Pythium on different plant families will be carried out to validate experimentally the patterns of descriptive community studies.

To date the primary results involve the sampling of woody plant communities in French Guiana and Peru, as we have experienced permitting delays and have just begun comprehensive field work in Manaus Brazil in late 2016.

Sampling of the woody plants in the 74 plots has yielded more than 2300 unique taxa, for which herbarium vouchers have been standardized across all plots and regions. We have found only 7% overlap in species presence between plots in Peru and French Guiana, underlining substantial geographic beta-diversity.

Other major results to date have involved the initial host plant-based lineage sampling in French Guiana and in Peru with supplemental funding obtained by PI Baraloto.

We chose eleven focal lineages that represent the breadth of Neotropical woody angiosperm diversity : Bombacoideae, Eschweilera, Inga, Lauraceae , Licania, Micropholis, Moraceae, Myrtaceae, Nyctaginaceae, Protium, and Rubiaceae.

We sampled soil fungal communities associated with each host sapling, including fine roots and soil cores. In French Guiana, project doctoral fellow Jean Legeay compared three independant approaches for oomycete community description: i) baiting assays followed by strain isolation on Petri dishes and Sanger sequencing, ii) metabarcoding on environmental DNA directly extracted from soil, and iii) metabarcoding on DNA extracted from leaves used as baits.

Project postdoctoral fellow Greg Lamarre developed a unique method for sampling arthropods on the focal trees, the socket trap. The method involves a cylindrical netting that can be rapidly encapsulated around a host plant and permits a snapshot sampling of all arthropods on the aerial biomass of the plant.

To date we have sampled more than 1500 stems of the 11 lineages across 31 plots in five regions of French Guiana; and more than 1200 stems of the 11 lineages across 28 plots in Peru.

The most outstanding feature of the project to date involves the scale and comprehensive nature of the experimental design and the resulting samples.
We have sampled remote locations and unique habitats in French Guiana, Peru and Brazil, collecting samples in areas that have heretofore been unsampled. Together, our efforts represent an unprecedented effort to characterize Amazonian forest diversity ; and we anticipate the discovery and descriptions of many new arthropod and fungal taxa in particular in addition to several putative new tree species.
The databases and modeling approaches we develop in this project will therefore contribute to an increased understanding of the factors that influence species turnover in the most diverse forests on earth. All three groups on which we focus are critically understudied in the tropics, and no attempt to date has been made to study these groups simultaneously for the same sites, especially with a well-replicated experimental design. The datasets we generate will therefore be essential for regional estimates of biodiversity, to assist policy makers to choose protected areas across the region, and to improve models of biodiversity dynamics in response to climate and land use change scenarios.
An important parallel contribution of the project has been the training of international students and the development of a multinational collaborative research team focusing on continental scale questions in Amazonian biodiversity. We obtained complementary funding from the AIRD GuyAmazon program which has permitted us to hold workshops for French, Brazilian, American and Peruvian professors, postdocs and graduate and undergraduate students in both Brazil and France. More than 40 students have been trained in these workshops, and the project has supported the research of 11 graduate students in France and Brazil.

Peer reviewed publications include:

Guevara, J. E., G. Damasco, C. Baraloto, P. V. A. Fine, M. C. Peñuela, O. Bánki, C. Castilho, A. Vincentini, D. Cárdenas, F. Wittmann, N. Targhetta, O. Phillips, J. Stropp, I. Amaral, P. Maas, A. Monteagudo, E. M. Jimenez, R. Thomas, R. Brienen, A. Duque, B. Magnusson, C. Ferreira, E. Honorio, F. de Almeida Matos, F. Ramirez Arevalo, J. Engel, P. Petronelli, R. Vasquez, and H. ter Steege. 2016. Low phylogenetic beta diversity and neoendemism in Amazonian white sand forests. Biotropica 48: 34-46.

Lamarre, G. P. A., D. S. Amoretti, C. Baraloto, F. Bénéluz, I. Mesones, and P. V. A. Fine. 2016. Phylogenetic overdispersion in Lepidoptera communities of Amazonian white-sand forests. Biotropica. 48: 101-109.

Fine, P. V. A. and C. Baraloto. 2016. Habitat endemism in white-sand forests: insights into the mechanisms of lineage diversification and community assembly of the Neotropical flora. Biotropica. 48: 21-33.

Roy, Mélanie, Heidy Schimann, Ricardo Braga-Neto, Rosa A E Da Silva, Jaime Duque, Dawn Frame, Felipe Wartchow, and Maria A Neves. “Diversity and Distribution of Ectomycorrhizal Fungi From Amazonian Lowland White-Sand Forests in Brazil and French Guiana.” Edited by Paul Fine. Biotropica 48, no. 1 (January 18, 2016): 90–100.

Lamarre, G. P. A., B. Hérault, I. Mesones, and P. V. A. Fine, & C. Baraloto. 2016. Taxonomic and functional composition of arthropod assemblages across contrasting Amazonian forests. Journal of Animal Ecology 85: 227-239.

Boudier Benjamin (2015). Etude de la diversité des Phytophthora spp. en forêt guyanaise. Mémoire de stage de Master 2, Université de Lorraine.

Schimann, H., Bach, C., Lengelle, J., Louisanna, E., Barantal, S., Murat, C., Buée, M. (2016). Diversity and Structure of Fungal Communities in Neotropical Rainforest Soils: The Effect of Host Recurrence. Microbial Ecology, 1-11.

Tropical plant diversity is extraordinarily high both at local and regional scales, including a significant component of beta-diversity, or the turnover in species composition across habitats and regions. Yet we still know little about the factors underlying species distributions, with more than half of all tropical plant species having been collected only once. In particular, the relative roles of biogeography, abiotic factors, and biotic factors in limiting plant species distributions remain a subject of debate. Natural enemies (both fungi and insect herbivores) have recently been shown to exert strong forces on plant community composition, and it has been hypothesized that such biotic interactions are far more important in driving plant species turnover than environmental drivers. Alternatively, natural enemies may be important at small scales, (local diversity) but may not influence turnover at the beta scale.
The NEBEDIV project represents a comprehensive evaluation of tropical forest beta-diversity across broad geographic and environmental gradients. We will integrate not only plot level analyses of more than 100 tree communities across Amazonia but also the first characterizations of soil fungi and insect herbivore communities at this scale. Critically, we will not only examine community-level correlations between these communities across spatio-environmental scales but also characterize host specialization of fungi and herbivorous insects, building on the extensive molecular phylogenetics work and collaborations we have established in previous international projects. We believe our teams are in a unique position to make this vital contribution given the extensive infrastructure we have established in recent years. The databases and modeling approaches we develop in NEBEDIV will contribute to an increased understanding of the factors that influence species turnover in the most diverse forests on earth. All three groups on which we focus are critically understudied in the tropics, and no attempt to date has been made to study these groups simultaneously for the same sites, especially with a well-replicated experimental design. The datasets we generate will therefore be essential for regional estimates of biodiversity, to assist policy makers to choose protected areas across the region, and to improve models of biodiversity dynamics in response to climate and land use change scenarios.
The databases and modeling approaches we develop in NEBEDIV will contribute to an increased understanding of the factors that influence species turnover in the most diverse forests on earth. All three groups on which we focus are critically understudied in the tropics, and no attempt to date has been made to study these groups simultaneously for the same sites, especially with a well-replicated experimental design. The datasets we generate will therefore be essential for regional estimates of biodiversity, to assist policy makers to choose protected areas across the region, and to improve models of biodiversity dynamics in response to climate and land use change scenarios.