Plant reproductive traits mediate tritrophic feedback effects within an obligate brood-site pollination mutualism

Krishnan, Anusha and Ghara, Mahua and Kasinathan, Srinivasan and Pramanik, Gautam Kumar and Revadi, Santosh and Borges, Renee M (2015) Plant reproductive traits mediate tritrophic feedback effects within an obligate brood-site pollination mutualism. In: OECOLOGIA, 179 (3). pp. 797-809.

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Abstract

Plants, herbivores and parasitoids affect each other directly and indirectly; however, feedback effects mediated by host plant traits have rarely been demonstrated in these tritrophic interactions. Brood-site pollination mutualisms (e.g. those involving figs and fig wasps) represent specialised tritrophic communities where the progeny of mutualistic pollinators and of non-mutualistic gallers (both herbivores) together with that of their parasitoids develop within enclosed inflorescences called syconia (hence termed brood-sites or microcosms). Plant reproductive phenology (which affects temporal brood-site availability) and inflorescence size (representing brood-site size) are plant traits that could affect reproductive resources, and hence relationships between trees, pollinators and non-pollinating wasps. Analysing wasp and seed contents of syconia, we examined direct, indirect, trophic and non-trophic relationships within the interaction web of the fig-fig wasp community of Ficus racemosa in the context of brood site size and availability. We demonstrate that in addition to direct resource competition and predator-prey (host-parasitoid) interactions, these communities display exploitative or apparent competition and trait-mediated indirect interactions. Inflorescence size and plant reproductive phenology impacted plant-herbivore and plant-parasitoid associations. These plant traits also influenced herbivore-herbivore and herbivore-parasitoid relationships via indirect effects. Most importantly, we found a reciprocal effect between within-tree reproductive asynchrony and fig wasp progeny abundances per syconium that drives a positive feedback cycle within the system. The impact of a multitrophic feedback cycle within a community built around a mutualistic core highlights the need for a holistic view of plant-herbivore-parasitoid interactions in the community ecology of mutualisms.

Item Type:	Journal Article
Publication:	OECOLOGIA
Publisher:	SPRINGER
Additional Information:	Copy right for this article belongs to the SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Keywords:	Inflorescence size; Interaction web; Feedback cycle; Plant-herbivore-parasitoid interactions; Trait-mediated indirect effect
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	24 Nov 2015 06:01
Last Modified:	24 Nov 2015 06:01
URI:	http://eprints.iisc.ac.in/id/eprint/52806

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