An ant’s-eye view of an ant-plant protection mutualism
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Ant protection of extrafloral nectar (EFN)-secreting plants is a common form of mutualism found in most habitats around the world. However, very few studies have considered these mutualisms from the ant, rather than the plant, perspective. In particular, a whole-colony perspective that takes into account the spatial structure and nest arrangement of the ant colonies that visit these plants has been lacking, obscuring when and how colony-level foraging decisions might affect tending rates on individual plants. Here, we experimentally demonstrate that recruitment of Crematogaster opuntiae (Buren) ant workers to the EFN-secreting cactus Ferocactus wislizeni (Englem) is not independent between plants up to 5 m apart. Colony territories of C. opuntiae are large, covering areas of up to 5,000 m2, and workers visit between five and 34 EFN-secreting barrel cacti within the territories. These ants are highly polydomous, with up to 20 nest entrances dispersed throughout the territory and interconnected by trail networks. Our study demonstrates that worker recruitment is not independent within large polydomous ant colonies, highlighting the importance of considering colonies rather than individual workers as the relevant study unit within ant/plant protection mutualisms.
KeywordsExtrafloral nectar Mutualism Polydomy Social insects Foraging
We would like to thank Joshua Ness and Bill Morris for their input throughout the design and conduct of these experiments. We also wish to thank David Holway, and all the members of the Bronstein lab group for their advice and comments on this manuscript. Carolyn Camp, Rebecca Ruppel, and Andrew Waser provided assistance in the field. This work was funded by an International Arid Lands Consortium (no. 03R-25) grant to Judith Bronstein, Ido Izhaki, and Ran Nathan, a University of Arizona Center for Insect Science grant to Michele Lanan, and a NIH Postdoctoral Excellence in Research and Teaching (PERT) fellowship to Michele Lanan. All experiments described herein comply with the laws of the country in which they were performed.
Conflict of interest
The authors declare that they have no conflict of interest.
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