Evolutionary diversity gradients in neotropical tree assemblages: New insights from Non-Flooded Evergreen forests

We investigated spatial patterns of evolutionary diversity along Neotropical Non-Flooded Evergreen Forests (NEF). We addressed the following questions: (i) What are the main NEF evolutionary groups? (ii) How evolutionary diversity varies across NEF environmental gradients? Based on a phylogeny of 1248 tree genera distributed over 1824 NEF assemblages, we examined the evolutionary differentiation using UPGMA and evopca. We measured lineage diversity (ses.PD) and structure (ses.MPD and ses.MNTD) and tested their response to environmental gradients using linear models. Phylogenetic dissimilarity segregated NEF into 12 evolutionary groups that largely confirm groups obtained in our previous work based on floristic similarity. However, one discrepancy was the amalgamation of Amazon and northern Atlantic Forest assemblages, while the southern Atlantic Forest remained an isolated group. Furthermore, Mesoamerica, which had been recognized as a single group, here split into six evolutionary groups. We found greater lineage diversity as altitude and latitude increased and temperature decreased. Evolutionary groups with the highest mean values of lineage diversity were those composed of Mesoamerican cloud forests, which harbor a mixture of tropical and temperate lineages representing a confluence of South and North American floras. We found that variations in phylogenetic diversity in NEF are primarily related to the coexistence of lineages of temperate and tropical climates in the mountain and nebular environments of NEF, indicating the strong contribution of extratropical niche conservatism in structuring evolutionary diversity.