Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Marazzi, Brigitte [1], Solís Neffa, Viviana [2].

Diversity and distribution of extrafloral nectaries in a region with three converging South American biomes.

Plants in over hundred angiosperm families and even some ferns have evolved extrafloral nectaries (EFNs): secretory structures that secrete nectar for ants (and other aggressive arthropods) to receive, in return, their protection from herbivores. Indeed, EFN occur on plant parts where most protection is needed: developing shoots, leaves, inflorescence, and floral buds. EFN diversity and the ecologically important mutualistic interactions that they mediate have been studied especially in tropical forests and savanna-like habitats (where they represent a large proportion of the vascular flora), but also in North American and Asian temperate regions (where they represent only a minor fraction), whereas they remain largely unknown from subtropical ecosystems. Therefore, here we investigate patterns in the phylogenetic and geographic distribution of EFN-bearing plants in a region of subtropical South America characterized by the convergence of three main biomes: Chaco, Espinal and Paranaense. Specifically, we assess the total diversity of EFN-plants and their proportion relative to the rest of the vascular plants and compare results for individual biomes to identify which one displays the highest EFN diversity. The region of biome convergence corresponds geographically to the Argentinean province of Corrientes. We compiled a list of vascular plant species with EFNs by comparing a checklist of Corrientes (extracted from the Flora of Argentina database) with reports from the literature and from the online world list of EFN-plants and with our observations of herbarium material and living specimens. We assigned EFN-species to the three biomes according to their geographic distribution. Approximately 32% of the 158 vascular plant families in our checklist potentially include species with EFNs. These are distributed in 163 angiosperm and 2 fern genera (~18% of all genera), totaling ~800 species (and have already been confirmed in 25% of them at the time of abstract submission). As reported for other ecosystems, Leguminosae (=Fabaceae) are on top with 34 genera and ~137 species, followed by Bignoniaceae (15 genera/~26 spp.), Euphorbiaceae (15/51), Malvaceae (9/43), and Cactaceae (7/13). The Chaco appears as the most EFN-rich biome, including over 55% and 65% of the EFN-bearing genera and species, respectively. This richness might be explained in part by the fact that legumes are a dominant component of the Chaco (27 genera; less than 20 in the other biomes). Furthermore, this biome is known for its diversity and abundance of ants. Our study sets the stage for needed research on ant-EFNs mutualisms in South American subtropical ecosystems.

1 - Instituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Agrarias, Sgto. Cabral 2131, Corrientes, 3400, Argentina
2 - Instituto de Botánica del Nordeste (UNNE- CONICET), Facultad de Ciencias Exactas y Naturales y Agrimensura (UNNE) , Sgto Cabral 2131, Corrientes, 3400, Argentina

Keywords:
ant-plant interactions
Argentina
Chaco
Cono Sur
extrafloral nectar
extranuptial nectaries
Leguminosae
mutualisms
plant defense
Subtropics.

Presentation Type: Oral Paper:Papers for Topics
Session: 9
Location: Cottonwoods North/Boise Centre
Date: Monday, July 28th, 2014
Time: 11:00 AM
Number: 9004
Abstract ID:664
Candidate for Awards:None