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Abstract How consumer diversity determines consumption efficiency is a central issue in ecology. In the context of predation and biological control, this relationship concerns predator diversity and predation efficiency. Reduced predation efficiency can result from different predator taxa eating each other in addition to their common prey (interference due to intraguild predation). By contrast, multiple predator taxa with overlapping but complementary feeding niches can generate increased predation efficiency on their common prey (enemy complementarity). When viewed strictly from an ecological perspective, intraguild predation and enemy complementarity are opposing forces. However, from an evolutionary ecology perspective, predators facing strong intraguild predation may evolve traits that reduce their predation risk, possibly leading to niche complementarity between enemies; thus, selection from intraguild predation may lead to enemy complementarity rather than opposing it. As specialized predators that live in or on their hosts, parasitoids are subjected to intraguild predation from generalist predators that consume the parasitoids' hosts. The degree to which parasitoid–predator interactions are ruled by interference versus enemy complementarity has been debated. Here, we address this issue with field experiments in a forest community consisting of multiple species of trees, herbivorous caterpillars, parasitoids, ants, and birds. Our experiments and analyses found no interference effects, but revealed clear evidence for complementarity between parasitoids and birds (not ants). Parasitism rates by hymenopterans and dipterans were negatively associated with bird predation risk, and the variation in the strength of this negative association suggests that this enemy complementarity was due to parasitoid avoidance of intraguild predation. We further argue that avoidance of intraguild predation by parasitoids and other arthropod predators may explain enigmatic patterns in vertebrate–arthropod–plant food webs in a variety of terrestrial ecosystems.
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Cheating death: selection on digestive physiology overcomes expected growth costs of antipredator defences
Abstract Organisms often face a fundamental trade-off between growth and predator avoidance, where traits that enhance growth—such as higher activity rates—also increase predation risk. While many species reduce activity in response to predators, potentially constraining growth, this trade-off can be mitigated if alternative traits, such as resource digestive efficiency, compensate for reduced activity. Such trait compensation could enable organisms to minimize growth costs while evading predators. To test this idea, we combined a mesocosm experiment with lab-based digestive physiological assays to examine survival selection and plasticity in damselfly larvae exposed to fish predators. We found that selection favoured less active individuals, yet this reduction in activity did not suppress growth. Instead, plastic increases in consumption rate, selection for greater assimilation efficiency, and weaker digestive stress responses allowed individuals to maintain growth despite reduced activity and elevated metabolic rates. Our results reveal that selection on digestive physiology can buffer organisms against the putative costs of predator avoidance, demonstrating how trait networks can decouple growth from predation risk in complex ecological systems.
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- Award ID(s):
- 2306183
- PAR ID:
- 10677486
- Editor(s):
- Bilde, Trine; Bleu, Josefa
- Publisher / Repository:
- OUP
- Date Published:
- Journal Name:
- Journal of Evolutionary Biology
- Volume:
- 38
- Issue:
- 11
- ISSN:
- 1420-9101
- Page Range / eLocation ID:
- 1507 to 1518
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/jeb/voaf100
