**5. Future perspectives**

are reduced, promoting a greater diversity in both the reproductive capacity and individual fitness [7, 39]. This can be observed in the higher occurrence of resin and latescent species in tropical regions, where the herbivory rate is higher [40, 42, 60]. If, on the one hand, tropical environments provide better conditions for plant metabolism in terms of photosynthesis and water availability, on the other hand, they also favor a greater diversity of phytophagous

**Figure 5.** Comparative evolutionary analysis of the distribution of laticifers and resin ducts in vascular plants. All orders containing one latescent or resinous species, at least, were labeled. The data were obtained from the surveys of Metcalfe [41], Lewinsohn [42], Langenheim [60], Montes [68] and personal observation optimized on the current phylogeny [69]

Although specialist insects can feed on some plants that produce latex or resin, generalist ones are highly affected by the properties of these secretions, which are either toxic or deterrent [2, 5, 23]. Strategies to reduce the intake of toxic plant secretions have appeared in multiple insect lineages, allowing to verify the convergent evolution of similar behaviors in several latescent or resinous plants, regardless of the plant morphology or phylogenetic

These specialized insects' ability to avoid the ingestion of toxic compounds involves leaf veintrenching, vein-cutting, girdling and leaf clipping strategies, among others, reducing by up to 90% the ingestion of the exudate [17, 23, 30, 79, 80]. It is noteworthy that some specialist

insects and pathogenic fungi [6, 61, 75].

using parsimoney analysis.

116 Ecosystem Services and Global Ecology

relationships [3, 5, 6, 17, 23, 25, 26, 30, 76–79].

Much remains to be studied about laticifers and ducts. Although their structures have been known for more than a century, and we have clear and objective definitions of them, discrepancies in the descriptions still remain. Divergences about the origin, mode of growth and the lack of information about the chemical composition of latex and resin of several groups still prevent a series of evolutionary analyses that may clarify the factors that determined the emergence of these structures in different groups, especially considering that both appeared multiple times throughout the evolution of plants.
