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

An n e x e sexpressed in such non-stereotyped sequences are often not peculiar in any respect, andhomologies cannot be proposed using the homology criterion of special quality. This situationprevented the analysis of a large part of animal behaviour within an accurate phylogeneticframework. In the best case, particular behaviours are coded “present” vs “absent” and thepositional information about their occurrence within a behavioural sequence is not considered.In the worst case, this has led some studies to map on the phylogenetic trees some broadbehavioural classes, leading to potentially biased reconstructions (as reported by Proctor,1996; Desutter-Grandcolas & Robillard, 2003; Grandcolas & D’Haese, 2004). The aim of thispaper is to propose a new methodology allowing the study of non-sterotyped sequences in aphylogenetic framework and to show its potential by applying it to a typical case of sequencesobtained from social interactions. This application is made for some social cockroaches, thebehaviour of which has already been copiously studied (Gautier, 1974; Grandcolas, 1991; vanBaaren & Deleporte, 2001; van Baaren etal., 2002, 2003a).ESTABLISHING A SUCCESSIVE EVENT-PAIRING METHOD TO STUDYBEHAVIOURAL SEQUENCESBehavioural sequences are ordered series of acts expressed by one or several individuals.These acts belong to the ethological repertoire of each species and are generally the firstcharacters used in phylogenetic analyses of behaviour. Most often, some informationabout the context of emittance of an act is taken into account when defining one or severalcharacters. For example, a particular grooming act in a grooming sequence is not equivalentto a similar grooming act in a dyadic (i.e., involving two interacting individuals) agonisticsequence; this grooming act is said to be “displaced” in the second case. Presence-absence ofthese different acts within an appropriate context already provides a first set of phylogeneticcharacters. However, the relative position of these acts within sequences is not yet taken intoaccount.The study of strereotyped behavioural sequences is straightforward. Differentsequences may be aligned and analysed as it was done by ethologists in non-phylogenetic andintraspecific comparisons of sequences (Abbott, 1995; Abbott & Tsay, 2000; Hay et al., 2004;Schlich, 2001; Van der Aalst et al., 2003; Wilson, Harvey & Thompson, 1999). Alignments ofstereotyped behavioural sequences for phylogenetic analysis can be generated in a dynamicway (Robillard et al., 2006b) via direct optimization (Wheeler, 1996) or used in a static wayin a standard phylogenetic analysis (Wilson et al., 1999). However, when sequences arenot stereotyped within species, there has been no way to use them directly to study speciesphylogenetic relationships.We propose here a new method to analyse behavioural characters for non-stereotypedsequences. This method was inspired by the procedure of event-pairing which has beendeveloped simultaneously by Mabee & Trendler (1996), Smith (1997) and Velhagen (1997)to study developmental sequences (Bininda-Emonds et al., 2002; Jeffery et al., 2002, 2005).281