View in EDS

Testing the contribution of vertebrate predators and leaf traits to mainland–island differences in insect herbivory on oaks.

Saved in:
Bibliographic Details
Title: Testing the contribution of vertebrate predators and leaf traits to mainland–island differences in insect herbivory on oaks.
Authors: Vázquez‐González, Carla, Abdala‐Roberts, Luis, Lago‐Núñez, Beatriz, Dean, Lydia S., Capó, Miquel, de la Mata, Raúl, Tack, Ayco J. M., Stenberg, Johan A., Covelo, Felisa, Cao, Ana, Cursach, Joana, Hernández‐Serrano, Ana, Hansen, Finn, Mooney, Kailen A., Moreira, Xoaquín
Source: Journal of Ecology; Jan2025, Vol. 113 Issue 1, p140-154, 15p
Subject Terms: INSECT pest control, GROWING season, PHENOLS, LEAF area, HERBIVORES
Abstract (English): Ecological theory predicts that herbivory should be weaker on islands than on mainland based on the assumption that islands have lower herbivore abundance and diversity. However, empirical tests of this prediction are rare, especially for insect herbivores, and those few tests often fail to address the mechanisms behind island–mainland divergence in herbivory. In particular, past studies have not addressed the relative contribution of top‐down (i.e. predator‐driven) and bottom‐up (i.e. plant‐driven) factors to these dynamics.To address this, we experimentally excluded insectivorous vertebrate predators (e.g. birds, bats) and measured leaf traits associated with herbivory in 52 populations of 12 oak (Quercus) species in three island–mainland sites: The Channel Islands of California vs. mainland California, Balearic Islands vs. mainland Spain, and the island Bornholm vs. mainland Sweden (N = 204 trees). In each site, at the end of the growing season, we measured leaf damage by insect herbivores on control vs. predator‐excluded branches and measured leaf traits, namely: phenolic compounds, specific leaf area, and nitrogen and phosphorous content. In addition, we obtained climatic and soil data for island and mainland populations using global databases. Specifically, we tested for island–mainland differences in herbivory, and whether differences in vertebrate predator effects or leaf traits between islands and mainland contributed to explaining the observed herbivory patterns.Supporting predictions, herbivory was lower on islands than on mainland, but only in the case of Mediterranean sites (California and Spain). We found no evidence for vertebrate predator effects on herbivory on either islands or mainland in any study site. In addition, while insularity affected leaf traits in some of the study sites (Sweden‐Bornholm and California), these effects were seemingly unrelated to differences in herbivory.Synthesis. Our results suggest that vertebrate predation and the studied leaf traits did not contribute to island–mainland variation patterns in herbivory, calling for more nuanced and comprehensive investigations of predator and plant trait effects, including measurements of other plant traits and assessments of predation by different groups of natural enemies. [ABSTRACT FROM AUTHOR]
Abstract (Spanish): Resumen: La teoría ecológica predice que la herbivoría ha de ser más débil en las islas que en el continente, ya que las islas tienen una menor abundancia y diversidad de herbívoros. Sin embargo, todavía no contamos con suficiente evidencia empírica que apoye estas predicciones, especialmente en lo que se refiere a la herbivoría por insectos, y los pocos estudios que existen a menudo no abordan los mecanismos que generan estos patrones de divergencia entre islas y continente en los niveles de herbivoría. En particular, las investigaciones previas no han examinado la contribución relativa de las fuerzas top‐down (es decir, efectos mediados por los depredadores) y bottom‐up (es decir, efectos mediados por los rasgos funcionales de las plantas) en estas dinámicas.En este trabajo, excluimos experimentalmente a depredadores insectívoros vertebrados (p. ej., aves, murciélagos) y medimos rasgos foliares asociados con la herbivoría en 52 poblaciones de 12 especies de robles (Quercus) en tres sitios insulares y continentales: las Islas del Canal de California vs. California continental, las Islas Baleares vs. España continental, y la isla de Bornholm vs. Suecia continental (N = 204 árboles). En cada sitio, al final de la época de crecimiento, medimos el daño foliar causado por insectos herbívoros en ramas control vs. ramas con exclusión de depredadores, y medimos diferentes rasgos foliares, en particular, la concentración de compuestos fenólicos, el área foliar específica y el contenido de nitrógeno y fósforo. Además, obtuvimos datos climáticos y de suelo de las poblaciones insulares y continentales utilizando bases de datos globales. Específicamente, evaluamos los efectos de la insularidad sobre la herbivoría y si existían patrones contrastados de los efectos de depredación y expresión de rasgos foliares entre islas y continentes que contribuyesen a explicar los patrones observados en la herbivoría.De acuerdo con la teoría ecológica, la herbivoría fue menor en las islas en comparación con el continente, pero solo en el caso de los sitios mediterráneos (California y España). No encontramos evidencia de efectos de los depredadores sobre la herbivoría en ninguno de los sitios de estudio, ya sea en las islas o en el continente. Además, aunque la insularidad afectó a la expresión de rasgos foliares en algunos de los sitios de estudio (Suecia‐Bornholm y California), estos efectos no estuvieron aparentemente relacionados con las diferencias observadas en la herbivoría.Síntesis. Nuestros resultados sugieren que la depredación por vertebrados y los rasgos foliares estudiados no contribuyeron a los patrones de variación entre islas y continente observados en los niveles de herbivoría, lo que plantea la necesidad de investigaciones más exhaustivas que incluyan la evaluación de otros rasgos funcionales y evaluaciones de la depredación por otros grupos de enemigos naturales de los herbívoros. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Complementary Index
Description
Abstract:Ecological theory predicts that herbivory should be weaker on islands than on mainland based on the assumption that islands have lower herbivore abundance and diversity. However, empirical tests of this prediction are rare, especially for insect herbivores, and those few tests often fail to address the mechanisms behind island–mainland divergence in herbivory. In particular, past studies have not addressed the relative contribution of top‐down (i.e. predator‐driven) and bottom‐up (i.e. plant‐driven) factors to these dynamics.To address this, we experimentally excluded insectivorous vertebrate predators (e.g. birds, bats) and measured leaf traits associated with herbivory in 52 populations of 12 oak (Quercus) species in three island–mainland sites: The Channel Islands of California vs. mainland California, Balearic Islands vs. mainland Spain, and the island Bornholm vs. mainland Sweden (N = 204 trees). In each site, at the end of the growing season, we measured leaf damage by insect herbivores on control vs. predator‐excluded branches and measured leaf traits, namely: phenolic compounds, specific leaf area, and nitrogen and phosphorous content. In addition, we obtained climatic and soil data for island and mainland populations using global databases. Specifically, we tested for island–mainland differences in herbivory, and whether differences in vertebrate predator effects or leaf traits between islands and mainland contributed to explaining the observed herbivory patterns.Supporting predictions, herbivory was lower on islands than on mainland, but only in the case of Mediterranean sites (California and Spain). We found no evidence for vertebrate predator effects on herbivory on either islands or mainland in any study site. In addition, while insularity affected leaf traits in some of the study sites (Sweden‐Bornholm and California), these effects were seemingly unrelated to differences in herbivory.Synthesis. Our results suggest that vertebrate predation and the studied leaf traits did not contribute to island–mainland variation patterns in herbivory, calling for more nuanced and comprehensive investigations of predator and plant trait effects, including measurements of other plant traits and assessments of predation by different groups of natural enemies. [ABSTRACT FROM AUTHOR]
ISSN:00220477
DOI:10.1111/1365-2745.14444