David presents his research from the Madidi Metabolics Project at the Botanical Society of America Conference in Anchorage, Alaska.
Henderson, David, Brian E. Sedio, J. Sebastián Tello, Belén Alvestegui, Leslie Cayola, Alfredo F. Fuentes, Nathan Muchhala, and Jonathan A. Myers. 2022. Testing the role that biotic interactions play in shaping elevational-diversity gradients: An ecological metabolomics approach. Botanical Society of America Conference, Anchorage, AK.
Abstract: Foundational hypotheses in ecology and evolution posit that stronger and more specialized biotic interactions contribute to higher species diversity at lower elevations and latitudes. Plant-chemical defenses mediate biotic interactions between plants and their natural enemies and provide a highly dimensional trait space in which chemically-mediated niches may facilitate plant species coexistence. However, the role of chemically-mediated niches in shaping plant communities remains largely untested across large-scale ecological gradients. To test this hypothesis, we used ecological metabolomics to quantify the chemical similarity of leaf secondary metabolites of more than 700 tree species in 16 tropical tree communities along an elevational gradient in Madidi National Park, Bolivia. We predicted that chemical similarity of co-occurring tree species would be lower in communities with higher species richness and warmer, wetter, and less-seasonal climates.
Our results support the hypothesis that chemically-mediated niches shape diversity gradients. Across the 16 forest plots, median pairwise chemical similarity among tree species decreased with species richness. Median chemical similarity also varied systematically with climate, with lower chemical similarity in communities with higher mean annual temperature, annual precipitation, and temperature annual range. Our results suggest that natural enemies impose a stronger biotic selective pressure on plant chemical defenses in more-diverse communities and more-productive climates. In turn, spatially-variable biotic pressure from natural enemies may be an important process shaping elevational-diversity gradients. Our study also illustrates the promise of ecological metabolomics in the study of biogeography, community ecology, and complex species interactions.