The ecological and evolutionary interplay between plants and herbivores may play a pivotal role in divergence, coexistence and speciation of both groups. Here we present data on Inga, one of the most speciose and locally diverse tree genera in the New World tropics.
Results/Conclusions
Anti-herbivore defenses show little phylogenetic signal suggesting that taxonomic conservatism is not widespread and that the tempo of evolution for defense traits is faster than for non-defense traits. Furthermore, different defensive adaptations (hairs, extrafloral nectaries, secondary chemistry, development, and phenology) are evolving independently. The major mode of divergence among Inga in secondary metabolites is most likely due to changes in gene regulation leading to novel combinations of common compounds. Despite similar habitat preferences, dozens of Inga species coexist at a single site. Neighboring individuals are more divergent in defenses than expected, indicating that novelty may reduce herbivore pressure. Thus high local diversity within Inga may result from niche differentiation in defenses against herbivores.