Distinguishing between apparent and actual randomness: a preliminary examination with Australian ants

A - Papers appearing in refereed journals

Reynolds, A. M., Ferdous, M. J. and Cheng, K. 2018. Distinguishing between apparent and actual randomness: a preliminary examination with Australian ants. Behavioral Ecology and Sociobiology. 72 (113). https://doi.org/10.1007/s00265-018-2527-1

AuthorsReynolds, A. M., Ferdous, M. J. and Cheng, K.

The correlated random walk paradigm is the dominant conceptual framework for modeling animal movement patterns. Nonetheless, we do not know whether the randomness is apparent or actual. Apparent randomness could result from individuals reacting to environmental cues and their internal states in accordance with some set of behavioral rules. Here we show how apparent randomness can result from one simple kind of algorithmic response to environmental cues. This results in an exponential step-length distribution in homogeneous environments and in generalized stretched exponential step-length distributions in more complex fractal environments. We find support for these predictions in the movement patterns of the Australian bull ant Myrmecia midas searching on natural surfaces and on artificial uniform and quasi-fractal surfaces. The bull ants spread their search significantly farther on the quasi-fractal surface than on the uniform surface, showing that search characteristics differed as a function of the substrate on which ants are searching. Further tentative support comes from a re-analysis of Australian desert ants Melophorus bagoti moving on smoothed-over sand and on a more strongly textured surface. Our findings call for more experimental studies on different surfaces to test the surprising predicted linkage between fractal dimension and the exponent in the step-length distribution.

KeywordsAustralian ants; Correlated random walks; Randomness; Algorithmic ; Myrmecia midas; Search
Year of Publication2018
JournalBehavioral Ecology and Sociobiology
Journal citation72 (113)
Digital Object Identifier (DOI)https://doi.org/10.1007/s00265-018-2527-1
PubMed ID29950754
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeBBSRC Strategic Programme in Smart Crop Protection
BBSRC Strategic Programme in Smart Crop Protection
Publisher's version
Output statusPublished
Publication dates
Online20 Jun 2018
Publication process dates
Accepted08 Jun 2018
Copyright licenseCC BY

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