Chemical similarity and local community assembly in the species rich tropical genus Piper

Abstract

Community ecologists have strived to find mechanisms that mediate the assembly of natural communities. Recent evidence suggests that natural enemies could play an important role in the assembly of hyper-diverse tropical plant systems. Classic ecological theory predicts that in order for coexistence to occur, species differences must be maximized across biologically important niche dimensions. For plant-herbivore interactions, it has been recently suggested that, within a particular community, plant species that maximize the difference in chemical defense profiles compared to neighboring taxa will have a relative competitive advantage. Here we tested the hypothesis that plant chemical diversity can affect local community composition in the hyper-diverse genus Piper at a lowland wet forest location in Costa Rica. We first characterized the chemical composition of 27 of the most locally abundant species of Piper. We then tested whether species with different chemical compositions were more likely to coexist. Finally, we assessed the degree to which Piper phylogenetic relationships are related to differences in secondary chemical composition and community assembly. We found that, on average, co-occurring species were more likely to differ in chemical composition than expected by chance. Contrary to expectations, there was no phylogenetic signal for overall secondary chemical composition. In addition we found that species in local communities were, on average, more phylogenetically closely related than expected by chance, suggesting that functional traits other than those measured here also influence local assembly. We propose that selection by herbivores for divergent chemistries between closely related species facilitates the coexistence of a high diversity of congeneric taxa via apparent competition.

Dispersal assembly of rain forest tree communities across the Amazon basin

“…However, our analyses tend to suggest that the average phylogenetic distance among co-occurring species of a given genus may depend simply on the age of the genus, although the exact phylogenetic distance estimates will depend on how well the genus has been sampled phylogenetically. Furthermore, the high degree of sympatric co-occurrence observed for the speciesrich genera studied here suggests that there might not be strong constraints on the number of co-occurring congeneric species, especially if they differ in terms of herbivore defense traits (42,44,45). One of the key factors influencing the number of co-occurring species of a given genus in a given Amazonian tree community may simply be the total diversity of that genus in the Amazon, because dispersal into regions, which provide species for local communities, does not seem to be limited (46).…”

Plant physical and chemical traits associated with herbivory in situ and under a warming treatment

“…For example, Rasmann and Agrawal () showed that the expression of secondary metabolites in Asclepias is associated with both the ecology and the phylogenetic position of the species. However, only a weak phylogenetic signal of leaf secondary chemicals was found for the genus Piper (Salazar, Jaramillo, & Marquis, ) and for the tropical species in the genus Inga (Kursar et al, ), both cases where co‐occurring species tend to diverge in chemical composition. Hence, whether plant chemical profiles have a strong phylogenetic signal and whether the latter is stronger than the signal from physical traits remain to be evaluated across systems.…”

Macroevolutionary patterns in overexpression of tyrosine: An anti‐herbivore defence in a speciose tropical tree genus, Inga (Fabaceae)

“…Secondary metabolites are one of the most effective defences plants have against insect herbivores, and play a central role in shaping both ecological and evolutionary interactions. For example, the high local diversity of trees in tropical rainforests may be maintained, not because coexisting species differ in their abiotic niches (Kraft, Valencia, & Ackerly, ; Sedio, Wright, & Dick, ; Wright, ), but because they differ in their secondary metabolites, and therefore do not share herbivores (Coley & Kursar, ; Endara et al, ; Kursar et al, ; Salazar, D., Jaramillo, A., & Marquis, R. J., ; Salazar, D., Jaramillo, M. A., & Marquis, R. J., ; Vleminckx et al, ). Because there appear to be an infinite number of chemical combinations, this translates into an infinite number of niches with respect to herbivore pressure.…”