Phylogénie Et Evolution Du Comportement Social Chez Les Blattes ...

An n e x e sBehavioral sequences were considered to begin when two cockroaches were closeenough for contact with their antennae, and to end when at least one cockroach was movingaway, preventing any further immediate contact, or after a lasting period of completeimmobility by both individuals. Interactions involving more than two individuals werenot considered. Initiator and responder were individualized for each behavioral sequence:the initiator was the individual executing the first act of the sequence whereas the otherindividual was called the responder. The acts were categorized as described in Bell et al.(1979), Gautier (1974) and Deleporte (1988): promoting contact, agonistic, dominance-like,avoiding contact, without clear significance. The definitions of acts (Table I) were taken fromBell et al. (1979) and van Baaren et al. (2003). “Body up and down” is not the equivalent of“jerk” (body vibration like a tremulation, Bell et al., 1979) but merely a slow vertical motionnot vibration-like. During “body leaning”, the individual presents its reclined dorsum to itspartner, extending the opposite legs. “Move away” and “escape” concluded the interaction,on the contrary of “move back” and “turn away” which never involved a departure but onlya relatively small motion. The observation periods of 15 minutes were repeated at leasteleven times on different groups of larvae for each species (11 replicates for T.a. and P.b.,14 replicates for S.l. and P.n., and 17 replicates for L.e.). All the dyadic interactions wererecorded and a transition matrix was build for each species. The mean sequence length(i.e. the mean number of behavioral acts within an interaction) and the mean number ofinteractions per hour were calculated and compared among the five species. Comparisonswere made for both statistics with a Kruskal-Wallis test (H) adjusted for ties as implementedin Minitab® 14 (Minitab, 1996), and followed by the multiple comparison test (Q) proposedby Dunn (1964).Transitions matrices were compared by a multiple correlation test: the Kendall’scoefficient of concordance (W) with correction for ties (Kendall and Babington-Smith, 1939).Transitions never displayed by any species were not included in the computation of thisstatistic.Finally, acts displayed by the responder were plotted against acts displayed by theinitiator, and a hypothetical correlation was tested for each species (correlation coefficient r).In case of symmetrical interactions, a significant correlation is expected.321