The phylogeny of the extant hexapod orders

Morphological and molecular data are marshalled to address the question of hexapod ordinal relationships. The combination of 275 morphological variabl es, 1000 bases of the small subunit nuclear rDNA (18S), and 350 bases of th e large subunit nuclear rDNA (28S) are subjected to a variety of analysis p arameters (indel and transversion costs), Representatives of each hexapod o rder are included with most orders represented multiply. Those parameters t hat minimize character incongruence (ILD of Mickevich and Farris, 1981, Sys t. Zool. SO, 351-370), among the morphological and molecular data sets are chosen to generate the best supported cladogram. A well-resolved and robust cladogram of ordinal relationships is produced with the topology (Crustace a ((Chilopoda Diplopoda) ((Collembola Protura) ((Japygina Campodeina) (Arch aeognatha (Zygentoma (Ephemcrida (Odonata ((((Mantodea Blattaria) Isoptera) Zoraptera) ((Plecoprera Embiidina) (((Orthoptera Phasmida) (Grylloblattari a Dermaptera)) ((((Psocoptera Phthiraptera) Thysanoptera) Hemiptera) ((Neur opteroidea Coleoptera) (((((Strepsiptera Diptera) Mecoptera) Siphonaptera) (Trichoptera Lepidoptera)) Hymenoptera)))))))))))))). (C) 2001 The Willi He nnig Society.