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

An n e x e s2.4. Attributes optimizationThree attributes were optimized a posteriori of the phylogenetic analyses using Wincladav1.00.08 (Nixon, 1999) and considering only unambiguous transformations: the presence ofpseudergates, the presence of true workers and the foraging behavior (Table 3). True workersand pseudergates evolved from different ontogenetic pathways (Noirot and Pasteels, 1987;Fig. 2) and can coexist in a same colony (e.g., Buchli, 1958). True workers separate early andirreversibly from the imaginal line. They present morphological specialization such as thedevelopment of the head and of mandibular muscles, and have rudimentary sex organs and nowings. They constitute the main working force in their colony. On the contrary, pseudergatesseparate late from the imaginal development. They are not specialized morphologically; theyhave short wing buds or no wings at all, and their genital organs are similar to those of thenymphs of the same size. Finally, they are not more active than nymphs or older larvae anddo not constitute the main working force in their natural society (Noirot and Pasteels, 1987).Therefore, pseudergates and true workers were optimized on the phylogenetic tree as twodifferent binary attributes (pseudergates: present/absent and true workers: present/absent).As explained in Grandcolas and D’Haese (2004), coding worker caste in a single multistatecharacter has not been employed since it would imply a homology statement betweenpseudergates and true workers which does not make sense as both can coexist in the samespecies. Mantids, cockroaches and Locusta migratoria do not exhibit developmental pathwaysleading to pseudergates or true workers and both attributes were coded absent in outgroups.The foraging behavior was split into three large categories according to Abe’s work(1987): one-piece type, intermediate type and separate type. One-piece type termites spendtheir life in a single piece of wood which serves as both shelter and food. Their nests occupythe space resulting from wood consumption. Intermediate type and separate type species haveuncoupled feeding from nesting sites but this uncoupling is more partial in the former. Thosespecies build various kinds of nests and galleries (Abe, 1987). One-piece, intermediate andseparate types are discrete states of the ecological character “foraging behaviour” and wereconsidered as unordered states.Those three attributes were not included in the matrix during tree reconstruction asthey cannot take part to the probabilistic phylogenetic analyses. They were optimized onthe preferred phylogenetic hypothesis (i.e. POY analysis under equal weighting) to infercaste evolution. However, optimizations on the phylogenetic trees obtained with differentmethodologies were discussed to point out possible discrepancies.347