Context dependency of rewards and services in an Indian ant-plant interaction: southern sites favour the mutualism between plants and ants

Chanam, Joyshree and Kasinathan, Srinivasan and Pramanik, Gautam K and Jagdeesh, Amaraja and Joshi, Kanchan A and Borges, Renee M (2014) Context dependency of rewards and services in an Indian ant-plant interaction: southern sites favour the mutualism between plants and ants. In: JOURNAL OF TROPICAL ECOLOGY, 30 (3). pp. 219-229.

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Abstract

Protection-based ant-plant mutualisms may vary in strength due to differences in ant rewards, abundance of protective ants and herbivory pressure. We investigated geographical and temporal variation in host plant traits and herbivory pressure at five sites spanning the distribution range of the myrmecophyte Humboldtia brunonis (Fabaceae) in the Indian Western Ghats. Southern siteshad, onaverage, 2.4 times greater abundance of domatia-bearing individuals, 1.6 times greater extrafloral nectary numbers per leaf, 1.2 times larger extrafloral nectary sizes, 2.2 times greater extrafloral nectar (EFN) volumes and a two-fold increase in total amino acid and total sugar concentrations in EFN compared with northern sites. Astrong protection-based mutualismwith ants occurred at only one southern site where herbivory was highest, suggesting that investments in attracting ants correlate with anti-herbivore benefits gained from the presence of protective ants. Our results confirm a temporally stable north-south gradient in myrmecophytic traits in this ant-plant as several of these traits were re-sampled after a 5-y interval. However, the chemical composition of EFN varied at both spatial and short-term temporal scales suggesting that only repeated measurements of rewards such as EFN can reveal the real spectrum of trait variation in an ant-plant mutualistic system.

Item Type:	Journal Article
Publication:	JOURNAL OF TROPICAL ECOLOGY
Publisher:	CAMBRIDGE UNIV PRESS
Additional Information:	Copy right for this article belongs to the CAMBRIDGE UNIV PRESS, 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA
Keywords:	amino acids; domatia; extrafloral nectar; geographical variation; Humboldtia brunonis; nectary; sugars
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	19 Aug 2014 09:09
Last Modified:	19 Aug 2014 09:09
URI:	http://eprints.iisc.ac.in/id/eprint/49563

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