. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 J. L. DENEUBOURG ET AL. Nest B 1,0 - 0,9 • * 0,8 • OJ 1 0,7 - o >> • , n I 0,31 •3 • 0,1 - 0,0. -•0,16 -• 0,14 -• -• 0,1 - • 0,08 - • 0,06 - • 0,04 - - 0,02 O 0 0 8 10 12 14 16 18 20 22 24 Number of ants in the chain Kigure 1. (A) Binary choice experimenlal set-up used to study chain competition in weaver ants. (B) Individual probabilities to enter a chain depending on its size (•) and to leave a chain depending on its size (O). between two large and identical shelters each with a carry- ing capacity (
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 J. L. DENEUBOURG ET AL. Nest B 1,0 - 0,9 • * 0,8 • OJ 1 0,7 - o >> • , n I 0,31 •3 • 0,1 - 0,0. -•0,16 -• 0,14 -• -• 0,1 - • 0,08 - • 0,06 - • 0,04 - - 0,02 O 0 0 8 10 12 14 16 18 20 22 24 Number of ants in the chain Kigure 1. (A) Binary choice experimenlal set-up used to study chain competition in weaver ants. (B) Individual probabilities to enter a chain depending on its size (•) and to leave a chain depending on its size (O). between two large and identical shelters each with a carry- ing capacity (S) large enough to contain the whole popula- tion. Tested groups of larvae show a strong tendency to aggregate on a unique, randomly selected, resting site (Fig. 4; Rivault and Cloarec. 1998). This collective choice results from a random walk and hence random discovery of the shelter by larvae and a probability Pt to leave the shelter / (P, = I/resting time). Due to inter-attraction between indi- viduals, this probability decreases with the number of con- specifics (X,) in the shelter / and is ruled by an empirical equation very similar to that proposed for Oecophvlla (Ri- vault et 1999: Ame ct al., Universite Libre de Bruxelles, unpubl. data): 1 + bX; (3) with LI = , b = 6. The characteristics of the shelter affect the resting time of the individuals, which for an isolated animal is =\la. The expression (1 + hX~) describes how the presence of other conspecifics increase the resting time. A theoretical model suggests that these basic mecha- nisms account for the clustering of insects (Rivault et al., 1999; Ame ct <//., unpubl. data). This model also predicts that other collective patterns can emerge, keeping the same individual rules. For instance, a group of cockroaches is able to select a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appeara
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
