| 1. |
- Theraulaz, Guy, et al.
(författare)
-
Spatial patterns in ant colonies
- 2002
-
Ingår i: Proceedings Of The National Academy Of Sciences Of The United States Of America. - : Proceedings of the National Academy of Sciences. ; 99:15, s. 9645-9649
-
Tidskriftsartikel (refereegranskat)abstract
- The origins of large-scale spatial patterns in biology have been an important source of theoretical speculation since the pioneering work by Turing (1952) on the chemical basis of morphogenesis. Knowing how these patterns emerge and their functional role is important to our understanding of the evolution of biocomplexity and the role played by self organization. However, so far, conclusive evidence for local activation-long-range inhibition mechanisms in real biological systems has been elusive. Here a well-defined experimental and theoretical analysis of the pattern formation dynamics exhibited by clustering behavior in ant colonies is presented. These experiments and a simple mathematical model show that these colonies do indeed use this type of mechanism. All microscopic variables have been measured and provide the first evidence, to our knowledge, for this type of self-organized behavior in complex biological systems, supporting early conjectures about its role in the organization of insect societies.
|
|
| 2. |
|
|
| 3. |
- Dussutour, Audrey, et al.
(författare)
-
Collective decisions in ants when foraging under crowded conditions
- 2006
-
Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 61, s. 17-30
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we examine the effect of crowding on the selection of a path in the mass-recruiting ant Lasius niger. In our experiment, ants had to go from their nest to a food source by crossing a diamond-shaped bridge, giving the choice between two paths. Two types of bridges were used: the first had two branches of equal length but different width while the second had two branches of different length and width. Experiments at high traffic volume always ended up with the selection of the wider branch, even if it was longer. This result shows that overcrowding on the narrow branch plays an essential role in the mechanism underlying the choice of route in ants. A mathematical model was developed to evaluate the importance of two mechanisms that could account for this result. The first is based on the difference in travel duration between the two paths. The second is based on the repulsive interactions between workers making head-on encounters. The model shows that travel duration per se is not sufficient to explain path choice. Rather, it is the interplay between trail following behaviour and repulsive interactions that allows ants to choose the path that minimizes their travel time. When choosing a path ants thus prefer to trade time against energy. Our results demonstrate that any environmental constraint that alters the dynamics of trail recruitment can lead to the emergence of adaptive foraging decisions without any explicit coding of information by the foragers at the individual level.
|
|
| 4. |
|
|
| 5. |
- Nicolis, Stamatios C., et al.
(författare)
-
Emerging patterns and food recruitment in ants : an analytical study
- 1999
-
Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193. ; 198:4, s. 575-592
-
Tidskriftsartikel (refereegranskat)abstract
- A model of food recruitment by social insects accounting for the competition between trails in the presence of an arbitrary number of sources is developed and analysed in detail. Both the case of identical environmental characteristics and the case where one source and the corresponding trail are different from the others are considered. Different collective responses depending on the environmental conditions, and without change of individual behaviour, are shown to exist, associated with the possibility that the colony may be led to exploit one source or a group of sources preferentially. The full bifurcation diagram of steady-state solutions is constructed from which the dominant exploitation patterns are identified. The biological relevance of the results is discussed and suggestions are made for their experimental testing in connection with the recruitment behavior of species using trail recruitment. The same phenomenological model can be used for different trail-laying species since the predictions are generic and not restricted to a given species, except for the parameter values used. (C) 1999 Academic Press.
|
|
| 6. |
- Nicolis, Stamatios C., et al.
(författare)
-
Optimality of collective choices : A stochastic approach
- 2003
-
Ingår i: Bulletin of Mathematical Biology. ; 65:5, s. 795-808
-
Tidskriftsartikel (refereegranskat)abstract
- Amplifying communication is a characteristic of group-living animals. This study is concerned with food recruitment by chemical means, known to be associated with foraging in most ant colonies but also with defence or nest moving. A stochastic approach of collective choices made by ants faced with different sources is developed to account for the fluctuations inherent to the recruitment process. It has been established that ants are able to optimize their foraging by selecting the most rewarding source. Our results not only confirm that selection is the result of a trail modulation according to food quality but also show the existence of an optimal quantity of laid pheromone for which the selection of a source is at the maximum, whatever the difference between the two sources might be. In terms of colony size, large colonies more easily focus their activity on one source. Moreover, the selection of the rich source is more efficient if many individuals lay small quantities of pheromone, instead of a small group of individuals laying a higher trail amount. These properties due to the stochasticity of the recruitment process can be extended to other social phenomena in which competition between different sources of information occurs. (C) 2003 Society for Mathematical Biology. Published by Elsevier Ltd. All rights reserved.
|
|
| 7. |
- Nicolis, Stamatios C., et al.
(författare)
-
The effect of aggregates on interaction rate in ant colonies
- 2005
-
Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 69:3, s. 535-540
-
Tidskriftsartikel (refereegranskat)abstract
- Direct contact between individuals is important for the organization of social insects. The question has been raised whether in ant colonies contact may also provide a mechanism to allow ants to estimate the density of the population in a nest and regulate their behaviour accordingly, as reflected by a subquadratic dependence of the number of interactions as a function of the density. We developed a kinetic model of encounters between individuals, and conducted an experiment with different densities of the species Lasius niger. These suggested that the subquadratic law is not due to active regulation by ants but arises, rather, as a consequence of the kinetics of the encounter process and the presence of small, temporary clusters of individuals. (c) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
|
|
| 8. |
- Vogel, David, et al.
(författare)
-
Transition from isotropic to digitated growth modulates network formation in Physarum polycephalum
- 2017
-
Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 50:1
-
Tidskriftsartikel (refereegranskat)abstract
- Some organisms, including fungi, ants, and slime molds, explore their environment and forage by forming interconnected networks. The plasmodium of the slime mold Physarum polycephalum is a large unicellular amoeboid organism that grows a tubular spatial network through which nutrients, body mass, and chemical signals are transported. Individual plasmodia are capable of sophisticated behaviours such as optimizing their network connectivity and dynamics using only decentralized information processing. In this study, we used a population of plasmodia that interconnect through time to analyse the dynamical interactions between growth of individual plasmodia and global network formation. Our results showed how initial conditions, such as the distance between plasmodia, their size, or the presence and quality of food, affect the emerging network connectivity.
|
|
