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A phylogenetic analysis of mitochondrial and nuclear rDNA sequences from
species of all the superfamilies of the insect order Orthoptera
(grasshoppers, crickets and relatives) confirmed that although
mitochondrial sequences provided good resolution of the youngest
superfamilies, nuclear rDNA sequences were necessary to separate the basal
groups. To try to reconcile these data sets into a single fully resolved
orthopteran phylogeny, we adopted consensus and combined data strategies.
The consensus analysis produced a partially resolved tree, lacking several
well-supported features of the individual analyses. However, this lack of
resolution was explained by an examination of resampled data sets that
identified the likely source of error as the relatively short length of
the individual mitochondrial data partitions. In a subsequent comparison
in which the mitochondrial sequences were initially combined, we observed
less conflict. We then used two approaches to examine the validity of
combining all of the data in a single analysis; comparative analysis of
trees recovered from resampled data sets and the application of a
randomization test. The results did not point to significant levels of
heterogeneity in phylogenetic signal between the mitochondrial and nuclear
data sets, and we therefore proceeded with a combined analysis.
Reconstructing phylogenies under the minimum evolution and maximum
likelihood optimality criteria, we examined monophyly of the major
orthopteran groups using nonparametric and parametric bootstrap analysis
and Kishino-Hasegawa tests. Our analysis suggests that phylogeny
reconstruction under the ML criteria is the most discriminating approach
for the combined sequences. The results indicate that the caeliferan
Pneumoroidea and Pamphagoidea (as previously suggested) are polyphyletic.
The Acridoidea is redefined to include all pamphagoid families other than
the Pyrgomorphidae, which we propose should be accorded superfamily
status.
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