2018 ESA Annual Meeting (August 5 -- 10)

COS 33-8 - Turnover in insect herbivore community and chemical composition in Protium (Burseraceae) trees across 1500km in the Amazon basin

Tuesday, August 7, 2018: 10:30 AM
354, New Orleans Ernest N. Morial Convention Center
Diego Salazar1, Milagros Ayarza Zuñiga2, Magno Vasquez Pilco3, Italo Mesones4, Emerson Merkel5, Carlos Nogueira5, Marcelle Sanches5, Fabricio Baccaro5, John Lokvam6 and Paul V.A. Fine7, (1)Biological Sciences, Florida International University, (2)Entomology, Instituto Nacional de Pesquisas da Amazonia, Brazil, (3)Graduate Program in Botany, Instituto Nacional de Pesquisas da Amazonia, Brazil, (4)Universidad Nacional de la Amazonía Peruana, Iquitos, Peru, (5)Biology, Universidade Federal do Amazonas, Brazil, (6)Integrative Biology, University of California, Berkeley, (7)Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
Background/Question/Methods

Herbivores can influence the geographic distribution of host plants, yet very little is known about the overlap in geographic distribution of plants and their herbivores in tropical forests, which harbor the great majority of both plant and insect species. The Geographic Mosaic Theory predicts that if herbivore communities change across different parts of a host’s geographical range, the host’s defensive composition is also likely to change. Given the high species turnover found in tropical regions, we predict that broadly distributed plant species will have different secondary chemistry and insect herbivore communities in different parts of their range. Ten Protium species (Burseraceae) were surveyed for herbivores every week for one year in two geographical locations 1500 km apart: Manaus, Brazil and Iquitos, Peru. Only confirmed feeding events were recorded. Herbivore species were DNA barcoded to confirm their identity across both sites and to determine the presence of potential cryptic species. To assess the role that changes in chemical composition and investment could play in the geographical consistency of plant-herbivore interactions, we used a metabolomic approach to quantify the changes in secondary metabolite composition for each Protium species at both locations.

Results/Conclusions

Herbivore species richness and abundance per plant species were very similar across both sites, and the vast majority of herbivores were polyphagous. In both sites, herbivore species richness and herbivore abundance were strongly correlated with host chemical diversity. Similarly, herbivore community composition at a broad phylogenetic scale was also very similar between sites. However, Protium herbivore beta-diversity across the two sites was extremely high (less than 1% shared species). Finally, the chemical composition of our 10 focal species showed small changes between the Iquitos and Manaus populations, but >95% of the secondary metabolites expressed by each Protium species were found at all sites and in similar amounts. Protium herbivore community composition was found to have a very high turnover, however, their broad phylogenetic composition appears very consistent, a pattern most likely forged by either historical co-evolutionary relationships or phylogenetic constraints. The small changes in host chemical composition suggest that chemistry is not likely to explain the high herbivore species turnover between these sites. Instead, the chemical diversity in Protium appears to function with similar effectiveness against herbivore communities in two widely-separated areas, suggesting that insect beta-diversity patterns are likely being caused by other factors, contrary to the predictions of Geographic Mosaic Theory.