A central goal in community ecology has been to understand the factors that influence community composition and assembly. Species pools, interspecific interactions, and habitat effects often are invoked in structuring plant and animal communities, but we lack a similar understanding in microbial communities. Plants harbor diverse communities of fungi within their leaf tissues (i.e., endophytic fungi), which may influence plant population and community dynamics through effects on host fitness and function. In the humid tropics, where endophyte abundance and diversity are predicted to be at their highest, researchers have investigated the role of host phylogeny, habitat characteristics, and environmental conditions in mediating community composition. Although much insight has been gained from these studies, the role of host attributes, particularly leaf functional traits, is not well understood. To address this knowledge gap, our study combines molecular analyses of fungal communities and leaf functional trait data to (i) quantify endophyte abundance and diversity in a diverse community of lowland tropical trees and (ii) identify leaf traits that influence endophyte community structure.
Our study was conducted at Barro Colorado Island (BCI) in Panama. We sampled leaves from 30 phylogenetically diverse plant species in the forest understory. For each species, we measured leaf mass per area, leaf thickness, leaf dry matter content, and leaf fracture toughness. Additionally, we isolated endophytes from each host using culture-based methods, and used Sanger sequencing to characterize endophyte diversity and community composition.
Initial results indicate no phylogenetic signal of host on endophyte communities, but host family explained a small but significant variation in fungal community composition across trees. Endophyte diversity was associated with leaf thickness, and endophyte community composition among trees reflected leaf mass per area and leaf fracture toughness. Ongoing research is focused on relating endophyte community structure to foliar chemical traits and using high-throughput sequencing for a more complete understanding of the factors influencing endophyte community composition in tropical forests.