Nests of red wood ants (Formica rufa-group) are positively associated with tectonic faults: a double-blind test

PeerJ. 2017 Oct 12:5:e3903. doi: 10.7717/peerj.3903. eCollection 2017.


Ecological studies often are subjected to unintentional biases, suggesting that improved research designs for hypothesis testing should be used. Double-blind ecological studies are rare but necessary to minimize sampling biases and omission errors, and improve the reliability of research. We used a double-blind design to evaluate associations between nests of red wood ants (Formica rufa, RWA) and the distribution of tectonic faults. We randomly sampled two regions in western Denmark to map the spatial distribution of RWA nests. We then calculated nest proximity to the nearest active tectonic faults. Red wood ant nests were eight times more likely to be found within 60 m of known tectonic faults than were random points in the same region but without nests. This pattern paralleled the directionality of the fault system, with NNE-SSW faults having the strongest associations with RWA nests. The nest locations were collected without knowledge of the spatial distribution of active faults thus we are confident that the results are neither biased nor artefactual. This example highlights the benefits of double-blind designs in reducing sampling biases, testing controversial hypotheses, and increasing the reliability of the conclusions of research.

Keywords: Clustering; Double-blind; Formicidae; Species distributions; Tectonic faults.

Grants and funding

Israel Del Toro was supported by a National Science Foundation Postdoctoral Research Fellowship; Aaron M. Ellison was supported by NSF grant (DEB-1136646); Nathan J. Sanders was supported by a National Science Foundation Dimensions of Biodiversity grant (NSF-1136703). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.