RT Journal Article
T1 Testing the contribution of vertebrate predators and leaf traits to mainland–island differences in insect herbivory on oaks
A1 Vázquez-González, Carla
A1 Abdala-Roberts, Luis
A1 Lago- Núñez, Beatriz
A1 Dean, Lydia S.
A1 Capó, Miguel
A1 de la Mata, Raúl
A1 Tack, Ayco J. M.
A1 Stenberg, Johan A.
A1 Covelo Núñez, Felisa
A1 Cao, Ana
A1 Cursach, Joana
A1 Hernández Serrano, Ana
A1 Hansen, Finn
A1 Mooney, Kailen A.
A1 Moreira, Xoaquín
K1 Bottom-up effects
K1 Chemical defences
K1 Island–mainland comparisons
K1 Multi-trophic interactions
K1 Plant–herbivore interactions
K1 Top-down effects
K1 Vertebrate predators
AB 1. 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.2. 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 theend 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.3. 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 unrelatedto differences in herbivory.4. 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.
PB Wiley
YR 2024
FD 2024-11-05
LK https://hdl.handle.net/10433/22008
UL https://hdl.handle.net/10433/22008
LA en
NO Journal of Ecology. 2024;00:1–15.
NO Datasets del artículo en: https://hdl.handle.net/10433/22009
NO Departamento de Sistemas Físicos, Químicos y Naturales
DS RIO
RD Apr 23, 2026