Abstract
Colony size is a fundamental attribute of insect societies that appears to play an important role in their organization of work. In the harvester ant Pogonomyrmex californicus, division of labor increases with colony size during colony ontogeny and among unmanipulated colonies of the same age. However, the mechanism(s) integrating individual task specialization and colony size is unknown. To test whether the scaling of division of labor is an emergent epiphenomenon, as predicted by self-organizational models of task performance, we manipulated colony size in P. californicus and quantified short-term behavioral responses of individuals and colonies. Variation in colony size failed to elicit a change in division of labor, suggesting that colony-size effects on task specialization are mediated by slower developmental processes and/or correlates of colony size that were missing from our experiment. In contrast, the proportional allocation of workers to tasks shifted with colony size, suggesting that task needs or priorities depend, in part, on colony size alone. Finally, although task allocation was flexible, colony members differed consistently in task performance and spatial tendency across colony size treatments. Sources of interindividual behavioral variability include worker age and genotype (matriline).
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Acknowledgments
We thank Phil Barden for assistance in the lab and Jon Harrison, Bert Hölldobler, and Bob Johnson for intellectual contributions. Research was supported by the National Science Foundation (IOS-0446415 to J.H.F., IOS-1011180 to J.H.F. and C.T.H., and a Graduate Research Fellowship to C.T.H.), the Graduate and Professional Student Association, Arizona State University to C.T.H., and the School of Life Sciences Undergraduate Research Program, Arizona State University to T.H.E.
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Holbrook, C.T., Eriksson, T.H., Overson, R.P. et al. Colony-size effects on task organization in the harvester ant Pogonomyrmex californicus . Insect. Soc. 60, 191–201 (2013). https://doi.org/10.1007/s00040-013-0282-x
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DOI: https://doi.org/10.1007/s00040-013-0282-x