Resolution of phylogenetic relationships of the major subfamilies of the Delphacidae (Homoptera: Fulgoroidea) using the mitochondrial ribosomal DNA

ABSTRACT

Abstract Delphacid relationships from the genus level to the subfamily have been completely resolved (among those taxa examined) using sequence data from the 3'end of the 12S gene. Monophyly of the non-asiracine subfamilies was strongly supported and the asiracine Ugyops was placed in the most basal position of the tree. Support levels for monophyly of the Delphacini increased after weighting transversions more heavily than transitions and after removing the cixiid outgroup from the dataset. Among the Delphacini, Conomelus and Megamelus were more closely related to each other than either was to Chloriona. These results are in agreement with the tree based on morphological characters. However, in contrast to morphological data our results strongly supported a sister group relationship between the Stenocraninae and the Kelisiinae. Although the 12S gene fragment gave some information about the species relationships within Chloriona, neither this fragment nor the 5'end of the 16S gene appear to be very useful for this level. Molecular evolutionary patterns provided evidence that there has been a shift in base composition from T to A during the early evolution of the non-Asiracinae. The non-Asiracinae also had comparatively fast substitution rates and these two observations are possibly correlated. In the 'modern' delphacid Chloriona, the AT content was comparatively low in regions free of constraints but this was not the case for 'non-modern' delphacids. The tRNA for valine has been translocated elsewhere, probably before the Delphacidae and Cixiidae diverged from each other.