Testing the level of ant activity associated with quorum sensing: An empirical approach leading to the establishment and test of a null-model

Abstract

. Testing the level of ant activity associated with quorum sensing; An empirical approach leading to the establishment and test of a null-model. Journal of Theoretical Biology, Elsevier, 2010, 266 (4) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractOn the basis of experimental observations, this paper develops two well-defined mathematical models for the level of activity of Pharaoh's ants within their nesting area, with the aim of providing a more general understanding of animal activity. Under specific conditions, we observe that the activity of ants within their nesting area appears to show no dependence on their density. Making the assumption that all ants move independently of one another, this behaviour can be mathematically modelled as a random process based on the binomial distribution. Developing the model on this basis allows an exponential distribution to be exposed that underlies the time-intervals between ants leaving the nesting area. Such a distribution is present, irrespective of whether the ant population in the nesting area remains constant or steadily depletes, and suggests that ant-ant interactions do not play any significant role in determining ant activity under these experimental conditions.The mathematical framework presented plays the role of a null model that will have a wide range of applications for detecting other determinants of activity-level (not addressed in this study) including environmental and social factors such as food availability, temperature, humidity, presence of pheromone trails, along with intraspecific and interspecific interactions outside the nest, and more generally. The null model should have applications to a range of organisms.Lastly, we discuss our data in relation to a recent study of ants leaving their nest (Richardson et al. 2010) in which the null model was rejected in favour of record dynamics, where ant-ant interactions were conjectured to play a role.Keywords: animal activity, movement, social insects, Pharaoh's ants, stochastic process, record dynamics. 3 IntroductionOrganisms frequently monitor the density of conspecifics in their immediate vicinity and modify their behaviour appropriately. For example, some bacteria secrete diffusible signals, for which they also express specific receptors, in order to signal and monitor their density.This mechanism was first discovered in the bacterium Vibrio fischeri; this species uses this technique to ensure that free-living bacteria, which are at low density in the sea, do not indulge in metabolically expensive luminescence, except when living symbiotically, at high density, in t...

Comment on P. Nouvellet, J.P. Bacon, D. Waxman, “Testing the level of ant activity associated with quorum sensing: An empirical approach leading to the establishment and test of a null-model”

“…(1) Nouvellet et al (2010) state that their experiments are comparable to our experiments, see e.g. section 8, 1st paragraph.…”

“…Systems exhibiting record dynamics are charactrerised by strong interactions, non-stationarity and non-exponential deceleration over time. Now we will comment specifically on that part of the paper by Nouvellet et al (2010) where they compare and contrast their result that ants do not interact with our result that ants do interact.…”

“…This is compatible with a model of independent Poissonian agents where their diminishing number (finite-size effect) is taken into account. Nouvellet et al (2010) compare and contrast their results with those in Richardson et al (2010a). We reported the results from one experimental and one control treatment on colonies of the ant Temnothorax albipennis as well as a null model very similar to theirs (Richardson et al, 2010a).…”

“…Comment on P. Nouvellet, J.P. Bacon, D. Waxman, ''Testing the level of ant activity associated with quorum sensing: An empirical approach leading to the establishment and test of a null-model' ' Nouvellet et al (2010) report the results from two experiments with the Pharaoh's ant, Monomorium pharaonis and test a null model. Their experimental set-up consists of a nest in an arena with a G-shaped object (like a hangman's scaffold) placed close to the nest.…”

“…We measure the exit times of all ants leaving the nest. Nouvellet et al (2010) measure the time ants fall from the tip of the scaffold placed in an arena. Hence, the latter study concerns the activity of ants that have already left their nest and subsequently happen to reach the particular point in the arena with the G-shaped object, choose to climb it, reach its tip and fall from it.…”