Zeit: 10.06.2010, 18.15 Uhr
A well-corroborated morphological scheme of interrelationships for centipedes has been in conflict with molecular data with respect to deep branching events. Expanded taxonomic coverage compared to previous analyses of centipede phylogeny adds longer fragments for 28S rRNA and a structural alignment as part of a sample of four genes (two nuclear ribosomal and two mitochondrial) for 111 extant species; these sequence data are combined with morphology under parsimony and maximum likelihood, exploring both traditional multiple sequence alignment and direct optimization approaches. The molecular data in combination yield trees that are highly congruent with morphology as regards the monophyly of all centipede orders as well as the major groups within each of the large orders but regardless of the optimality criterion or alignment strategy, the Tasmanian/New Zealand Craterostigmomorpha is resolved more basally by the molecular data than is favoured by morphology or combination of the molecular and morphological characters. Addition of morphology overturns the more basal placement of Craterostigmomorpha in favour of the traditional morphological resolution and eliminates the need to posit major character reversals with respect to developmental mode and maternal care. Calibration of the tree with Palaeozoic and Mesozoic fossils for a relaxed clock analysis corroborates the palaeontological signal that divergences between centipede orders date to the Silurian and earliest Devonian, and familial divergences are likewise almost wholly Palaeozoic. Ongoing work on Scolopendromorpha employs new morphological studies (especially from the preoral chamber and the foregut) and a multi-locus molecular sample: results to date indicate that blindness and a specialised gizzard unique to blind lineages evolved only once in scolopendromorphs.
