Using caddisfly (Trichoptera) case-building behaviour in higher level phylogeny reconstruction

Higher level phylogenetic analyses rarely include behavioural data, predomi nantly because such groups seldom have complex behaviours that are suscepti ble to analysis. Even when broad groups do share a complex behaviour, there is skepticism about the appropriateness of using behavioural traits in hig her level phylogenetic analyses. The Integripalpia is a suborder of caddisf lies and is an appropriate group to investigate the use of behaviour in hig her level analyses because all larvae use a complex suite of behaviours to build portable cases. A thorough investigation of case-building in 10 famil ies (19 exemplar genera) yielded 24 behavioural characters. A parsimony ana lysis produced 87 equally parsimonious trees (length = 56 steps, consistenc y index (CI) = 0.84, retention index (RI) = 0.88) that supported the monoph yly of the integripalpian families, except for the Limnephilidae. Interfami lial relationships, although resolved, were not well supported with behavio ur. Certain interfamilial relationships have also been difficult to establi sh reliably with morphological information, indicating a need for more char acters (e.g., molecular) at this taxonomic level. This study indicates that if taxa share a complex behaviour (e.g., case building), then regardless o f taxonomic level, one is likely to find shared derived behavioural charact ers that are useful for phylogeny reconstruction.