Foliar Endophyte Communities and Leaf Traits in Tropical Trees

Tropical forests contain a great diversity of plant and fungal species. Plant-fungal interactions contribute to this richness, ranging in outcomes from pathogenic to mutualistic (Gilbert and Strong 2007; Rodriguez et al. 2009; Mangan et al. 2010). Although only a small fraction of tropical plant species has been assessed for foliar endophytes-fungi that live asymptomatically in leaf tissue-it has been suggested that foliar endophytes are hyperdiverse in tropical forests (Arnold et al. 2000; Zimmerman and Vitousek 2012). Understanding the factors that shape endophyte communities is important, given the diverse roles of endophytes in plant interactions with antagonists (Mejia et al. 2008), their effects on plant physiology (Arnold and Engelbrecht 2007; Mejía et al. 2014), and the potential of some endophytes to act as cryptic pathogens (e.g., Slippers and Wingfield 2007; Alvarez-Loayza et al. 2011; Adame-Álvarez et al. 2014). This chapter considers the degree to which theory applied toward understanding plant diversity applies also to fungal endophyte diversity, with an emphasis on encompassing factors such as functional traits and phylogenetic history in shaping tropical plant-symbiont interactions.