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Abstract Evolutionary correlations between chemical defense and protection by mutualist bodyguards have been long predicted, but tests of these patterns remain rare. We use a phylogenetic framework to test for evolutionary correlations indicative of trade-offs or synergisms between direct defense in the form of plant secondary metabolism and indirect defense in the form of leaf domatia, across 33 species in the wild grape genus, Vitis. We also performed a bioassay with a generalist herbivore to associate our chemical phenotypes with herbivore palatability. Finally, we tested whether defensive traits correlated with the average abiotic characteristics of each species’ contemporary range and whether these correlations were consistent with plant defense theory. We found a negative evolutionary correlation between domatia size and the diversity of secondary metabolites in Vitis leaf tissue across the genus, and also that leaves with a higher diversity and richness of secondary metabolites were less palatable to a generalist herbivore, consistent with a trade-off in chemical and mutualistic defense investment. Predictions from plant defense theory were not supported by associations between investment in defense phenotypes and abiotic variables. Our work demonstrates an evolutionary pattern indicative of a trade-off between indirect and direct defense strategies across the Vitis genus.
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This content will become publicly available on May 14, 2026
Evolutionary trajectories of multiple defense traits across phylogenetic and geographic scales in Vitis
The processes driving defense trait correlations may vary within and between species based on ecological or environmental contexts. However, most studies of plant defense theory fail to address this potential for shifts in trait correlations across scales. In this work, we tested for correlations between multiple defensive traits (secondary chemistry, carbon to nitrogen ratio, domatia, leaf toughness, trichomes, and pearl bodies) across a common garden of 21Vitisspecies and eighteen genotypes of the speciesVitis ripariato identify when and where patterns of defense trait evolution persist or break down across biological scales. Additionally, we asked whetherVitisdefense trait investment correlates with environmental variables as predicted by plant defense theory, using environmental metrics for eachVitisspecies andV. ripariagenotype from the GBIF and WorldClim databases. We tested for correlations between defense trait investment, herbivore palatability, and environmental variables using phylogenetically informed models. Beyond a few likely physiological exceptions, we observed a lack of significant correlations between defense traits at both intra‐ and interspecific scales, indicating that these traits evolve independently of each other inVitisrather than forming predictable defense syndromes. We did find that investment in carbon:nitrogen (at both scales) and pearl bodies increases with proximity to the equator, demonstrating support for plant defense theory's prediction of higher investment in defenses at more equatorial environments for some, but not all, defense traits. Overall, our results challenge commonly held hypotheses about plant defense evolution, namely the concept of syndromes, by demonstrating that strong correlations between defense traits are not the prevailing pattern both across and withinVitisspecies. Our work also provides the first comprehensive evaluation of the evolutionary divergence in approaches thatVitis, a genus with significant agricultural value, have evolved to defend themselves against herbivores.
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- Award ID(s):
- 2236747
- PAR ID:
- 10603873
- Publisher / Repository:
- Ecography
- Date Published:
- Journal Name:
- Ecography
- ISSN:
- 0906-7590
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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