Editor: Heike Lutermann
The emergence of reproductive division of labor in forced queen groups of the ant Pogonomyrmex barbatus
Article first published online: 15 AUG 2013
© 2013 The Zoological Society of London
Journal of Zoology
Volume 291, Issue 1, pages 12–22, September 2013
How to Cite
Cahan, S. H. and Gardner-Morse, E. (2013), The emergence of reproductive division of labor in forced queen groups of the ant Pogonomyrmex barbatus. Journal of Zoology, 291: 12–22. doi: 10.1111/jzo.12071
- Issue published online: 27 AUG 2013
- Article first published online: 15 AUG 2013
- Manuscript Accepted: 14 MAY 2013
- Manuscript Revised: 10 MAY 2013
- Manuscript Received: 30 SEP 2012
- NSF. Grant Number: DEB-0919052
- University of Vermont Undergraduate Research
Figure S1. Histograms of expected and observed sharing of excavation behavior of pairs of Pogonomyrmex barbatus queens in (a) 2011 and (b) 2012. A value of 0 indicates excavation was performed solely by one queen, while a value of 1 indicates equal task performance. Because nests were not observed for the same total duration in the two years (see Methods), results for each year were analyzed separately. Expected frequencies were generated by randomly pairing excavation data from control queens excavating nests alone, sampled with replacement. Median excavation sharing in observed pairs was significantly lower than expected in both years (2011: predicted median = 0.55, observed median = 0.19, P < 0.01; 2012: predicted = 0.44, observed = 0.27, P < 0.05).
Figure S2. Histogram of expected and observed distribution of reproductive sharing between paired queens, pooled over the two years. Expected values were generated by randomly sampling with replacement and pairing two productivity values from the set of control single queen nests one hundred times. Median reproductive sharing in observed pairs was significantly lower than expected (predicted median = 0.60, observed median = 0.40, P < 0.01).
Text S1. Custom python script for generating an expected distribution of LF/HF values under the null hypothesis that all task asymmetry is due to intrinsic variation in task performance. Comments explaining individual lines of code are indicated with a # sign.
Text S2. Custom python script for running a randomization test comparing the observed median LF/HF value to the null distribution. The randomization test calculates a distribution of medians derived from 1000 simulated datasets of identical sample size to the observed data, drawn at random from the expected distribution of LF/HF values if all task asymmetry were caused by intrinsic variation in task performance. Observed medians falling below the bottom 5% of the expected medians indicate significantly amplified division of labor for the focal task. Comments explaining individual lines of code are indicated with a # sign.
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