ATBC 2008 - 2008 Alwyn Gentry Awards

The Annual Meeting of the Association for Tropical Biology and Conservation

2008 Alwyn Gentry Awards

Oral : Maylin Adriana Gonzales

Towards large-scale inventories of tropical trees using DNA-barcoding techniques. Mailyn Adriana Gonzalez¹, Christopher Baraloto², Julien Engel³, Scott Mori⁴, Pascal Petronelli², Bernard Riéra⁵, Aurelien Roger¹, Christophe Thébaud¹, Jérôme Chave¹
¹ Laboratoire d'Evolution et Diversité Biologique, Université Paul Sabatier, Toulouse, France; ² Unité Mixte de Recherche Ecologie des Forêts de Guyane, campus agronomique, Kourou, French Guiana; ³ et Diversité Biologique, Université Paul Sabatier, Toulouse, France ; ⁴ New York Botanical Garden; ⁵ Laboratoire Fonctionnement, Evolution et Mécanismes Régulateurs des Ecosystèmes Forestiers, Brunoy, France.

Abstract. The workload required for identifying tropical plants remains a major impediment to the development of large-scale biodiversity surveys in the tropics. Here we assess whether molecular identification tools, specifically ‘DNA-barcoding’ techniques, may help in the taxonomic identification of tropical tree during large-scale inventory programs. This approach relies upon a combination of small, universal, and highly variable DNA sequences that should be unique to each species. We tested this approach in 143 species belonging to 44 woody plant families collected at the Nouragues Station, French Guiana. We sampled several species per genus and two individuals per species when possible and maximized the phylogenetic coverage of woody angiosperms at our site. We sequenced 5 DNA plastid regions (from 284 to 678 bp) from the tissue of 192 plants providing a first DNA barcoding reference database for tropical woody plants. Identification based on sequences alone allowed us to identify unambiguously all individuals to the family level and 90% of them to the genus level. A combination of two DNA markers provided enough variation to distinguish species in about 80% of the samples. In addition to facilitating the identification of rare individuals, our dataset enabled us to improve the estimation of phylogenetic diversity of sampled area. DNA-barcoding of plants should become a standard tool in the toolkit of tropical ecologist and pave the road for biodiversity sampling of unprecedented size.

Finalists for the Oral Award: Adriana Bravo & Alexandra Pardow

Poster : Elodie Courtois

Emission of plant volatiles in the vegetative parts of 33 tropical tree species in French Guiana. Elodie Courtois¹, Didier Stien ², Pierre-Alain Blandinieres², Jerome Chave¹
¹ laboratoire Evolution et Diversité Biologique, Toulouse
² laboratoire Matériaux et Molécules en Milieu Amazonien, Cayenne

Abstract. Volatile organic compounds (VOCs) released by plants are implicated in a range of functions (pollinator attraction, defense against herbivores). A number of studies have focused on the VOCs emitted by flowers, much less on the defensive compounds emitted by other plant organs such as leaves and bark. To examine the evolution and function of these vegetative VOCs, we characterized the bouquet of VOCs emitted by the bark and the leaves for 189 individuals belonging to 33 woody tropical species spread in 16 families in two study sites in French Guiana (Nouragues and Paracou research stations). VOCs were extracted by SPME (Solid Phase Micro Extraction) and analyzed by GC-MS (Gas Chromatography-Mass Spectrometry). It allow us to isolate 392 molecules divided into 6 Green Leaf Volatiles (1.5%), 83 monoterpenes (21%) and 303 sesquiterpenes (77%). Of our 31 species in which leaves were analyzed, 14 emitted less than 5 compounds and 9 emitted more than 20 compounds (families Annonaceae, Burseraceae, Meliaceae and Caesalpiniaceae). Of the 33 species in which bark samples were analyzed, all had more than 5 compounds, and 11 had more than 20 compounds (same families as above). Three molecules were ubiquitous (encountered in more than 50% of the samples), while 313 molecules (79%) were found in less than 10 samples. This result confirms the astounding chemical diversity of tropical rain forest trees.