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Organismal phenotypes often co-vary with environmental variables across broad geographic ranges. Less is known about the extent to which phenotypes match local conditions when multiple biotic and abiotic stressors vary at fine spatial scales. Bittercress (Brassicaceae: Cardamine cordifolia), a perennial forb, grows across a microgeographic mosaic of two contrasting herbivory regimes: high herbivory in meadows (sun habitats) and low herbivory in deeply shaded forest understories (shade habitats). We tested for local phenotypic differentiation in plant size, leaf morphology, and anti-herbivore defense (realized resistance and defensive chemicals, i.e., glucosinolates) across this habitat mosaic through reciprocal transplant–common garden experiments with clonally propagated rhizomes. We found habitat-specific divergence in morphological and defensive phenotypes that manifested as contrasting responses to growth in shade common gardens: weak petiole elongation and attenuated defenses in populations from shade habitats, and strong petiole elongation and elevated defenses in populations from sun habitats. These divergent phenotypes are generally consistent with reciprocal local adaptation: plants from shade habitats that naturally experience low herbivory show reduced investment in defense and an attenuated shade avoidance response, owing to its ineffectiveness within forest understories. By contrast, plants from sun habitats with high herbivory show shade-induced elongation, but no evidence of attenuated defenses canonically associated with elongation in shade-intolerant plant species. Finally, we observed differences in flowering phenology between habitat types that could potentially contribute to inter-habitat divergence by reducing gene flow. This study illuminates how clonally heritable plant phenotypes track a fine-grained mosaic of herbivore pressure and light availability in a native plant.
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This content will become publicly available on January 21, 2026
The impact of host biogeography, ecology, evolutionary history, and architecture on the structure of rolled‐leaf beetle assemblages of Costa Rican Zingiberales
Abstract Determining the factors affecting the structure of insect herbivore communities is a major challenge in ecology. Previous research demonstrated that plant defenses determine plant‐herbivore associations. However, non‐defensive variables may also explain why some plant species are associated with more diverse insect herbivore assemblages than others. Neotropical rolled‐leaf beetles (CephaloleiaandChelobasis) complete their life cycle inside the young rolled leaves of their host plants in the order Zingiberales. The diet breadth of each species in this assemblage is particularly well‐known at our study site, La Selva Biological Station in Costa Rica. This study focused on the following non‐defensive variables: host plant elevational and geographic range size, soil type, habitat, local abundance, plant size, and leaf size. Because plant characteristics among closely related plants are not independent, we analyzed these variables in a phylogenetic context. We detected a positive effect of leaf width on rolled‐leaf beetle species richness (explaining 55% of the variation), abundance (28% of the variation and 57% when habitat is included in the model), diversity (37% of the variation), and community structure (6% of the variation, and 21%–26% when taxonomic family is included in the model). Our study demonstrates that Zingiberales leaf width influences positively rolled‐leaf beetle species richness, abundance, and diversity. This effect varies among plant families. Our study shows that plant architecture plays an important role in structuring insect herbivore assemblages in Zingiberales. Our results highlight the importance of including variables beyond plant defenses to understand the ecology and evolution of plant‐herbivore interactions.
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- Award ID(s):
- 2222328
- PAR ID:
- 10579393
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Biotropica
- Volume:
- 57
- Issue:
- 1
- ISSN:
- 0006-3606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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