Abstract
Trophic shifts of generalist consumers can have broad food-web and biodiversity consequences through altered trophic flows and vertical diversity. Previous studies have used trophic shifts as indicators of food-web responses to perturbations, such as species invasion, and spatial or temporal subsidies. Resource pulses, as a form of temporal subsidies, have been found to be quite common among various ecosystems, affecting organisms at multiple trophic levels. Although diet switching of generalist consumers in response to resource pulses is well documented, few studies have examined if the switch involves trophic shifts, and if so, the directions and magnitudes of the shifts. In this study, we used stable carbon and nitrogen isotopes with a Bayesian multi-source mixing model to estimate proportional contributions of three trophic groups (i.e. producer, consumer, and fungus-detritivore) to the diets of the White-footed mouse (Peromyscus leucopus) receiving an artificial seed pulse or a naturally-occurring cicadas pulse. Our results demonstrated that resource pulses can drive trophic shifts in the mice. Specifically, the producer contribution to the mouse diets was increased by 32% with the seed pulse at both sites examined. The consumer contribution to the mouse diets was also increased by 29% with the cicadas pulse in one of the two grids examined. However, the pattern was reversed in the second grid, with a 13% decrease in the consumer contribution with the cicadas pulse. These findings suggest that generalist consumers may play different functional roles in food webs under perturbations of resource pulses. This study provides one of the few highly quantitative descriptions on dietary and trophic shifts of a key consumer in forest food webs, which may help future studies to form specific predictions on changes in trophic interactions following resource pulses.
Highlights
Food-web structure can strongly influence the functioning and diversity of communities and ecosystems [1,2,3]
Stable isotope values of the dietary sources and mice The d13C values of the plant, above-ground arthropods, and fungus-detritivore groups indicate that the food webs at the study site had a C3-based carbon source (Table S2)
We demonstrated that resource pulses can drive trophic shifts in an omnivorous consumer, the White-footed mouse
Summary
Food-web structure can strongly influence the functioning and diversity of communities and ecosystems [1,2,3]. Generalist consumers, multi-trophic omnivores, can alter trophic flows through diet switching, and have long been recognized as a dynamically important feature of food webs [4]. Many studies used trophic shifts, diet switching across trophic levels, as indicators of food-web responses to perturbations, such as the invasion of exotic species, and spatial or temporal subsidies to a system [5,6]. As a form of temporal subsidies, a resource pulse can have broad effects on species interactions [7,8]. The numerical responses of the generalist consumers may be so strong that they themselves become a secondary resource pulse, creating cascading effects [11]. Investigating different aspects of responses from generalist consumers to resource pulses is critical to our overall understanding of community ecology
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
