Background/Question/Methods
There is increasing interest in patterns of trait variation and phylogenetic structure in tropical tree communities. Examining these patterns can help us understand the forces that govern the composition of natural biological communities. While there now exist multiple studies on the topic, most are conducted at the coarse taxonomic level of the entire tree community and lack phylogenetic resolution at lower taxonomic levels. However, it is at low taxonomic levels that competition is expected to be most intense, and patterns may be most evident.
We examine the phylogenetic and trait structure of tropical tree communities at a low taxonomic level (within the genus Inga: Fabaceae) in two locations: Panama and Madre de Dios, Peru. In Panama, we assess patterns within subplots of the 50 ha forest dynamics plot on BCI, while in Peru, we examine patterns for multiple communities in diverse habitat types scattered across a 150 by 200 km area.
Results/Conclusions
In Panama, we find evidence for phylogenetic overdispersion (closely related species co-occurring less often than would be expected by chance), while in Peru, we find phylogenetic underdispersion. In Peru, using species-level data on ecological traits related to resource-use, we assessed whether co-occurring species differ more for these traits than expected by chance. This does not seem to be the case. However, we did find that co-occurring species in both locations differ more for herbivore-defense traits than expected by chance. Thus, regardless of the phylogenetic structure present, it seems that coexistence in Inga communities may be mediated by divergence in herbivore defense strategies.