The Strepsiptera Problem: Phylogeny of the Holometabolous Insect Orders Inferred from 18S and 28S Ribosomal DNA Sequences and Morphology

Abstract

Phylogenetic relationships among the holometabolous insect orders were inferred from cladistic analysis of nucleotide sequences of 18S ribosomal DNA (rDNA) (85 exemplars) and 28S rDNA (52 exemplars) and morphological characters. Exemplar outgroup taxa were Collembola (1 sequence), Archaeognatha (1), Ephemerida (1), Odonata (2), Plecoptera (2), Blattodea (1), Mantodea (1), Dermaptera (1), Orthoptera (1), Phasmatodea (1), Embioptera (1), Psocoptera (1), Phthiraptera (1), Hemiptera (4), and Thysanoptera (1). Exemplar ingroup taxa were Coleoptera: Archostemata (1), Adephaga (2), and Polyphaga (7); Megaloptera (1); Raphidioptera (1); Neuroptera (sensu stricto = Planipennia): Mantispoidea (2), Hemerobioidea (2), and Myrmeleontoidea (2); Hymenoptera: Symphyta (4) and Apocrita (19); Trichoptera: Hydropsychoidea (1) and Limnephiloidea (2); Lepidoptera: Ditrysia (3); Siphonaptera: Pulicoidea (1) and Ceratophylloidea (2); Mecoptera: Meropeidae (1), Boreidae (1), Panorpidae (1), and Bittacidae (2); Diptera: Nematocera (1), Brachycera (2), and Cyclorrhapha (1); and Strepsiptera: Corioxenidae (1), Myrmecolacidae (1), Elenchidae (1), and Stylopidae (3). We analyzed approximately 1 kilobase of 18S rDNA, starting 398 nucleotides downstream of the 5' end, and approximately 400 bp of 28S rDNA in expansion segment D3. Multiple alignment of the 18S and 28S sequences resulted in 1,116 nucleotide positions with 24 insert regions and 398 positions with 14 insert regions, respectively. All Strepsiptera and Neuroptera have large insert regions in 18S and 28S. The secondary structure of 18S insert 23 is composed of long stems that are GC rich in the basal Strepsiptera and AT rich in the more derived Strepsiptera. A matrix of 176 morphological characters was analyzed for holometabolous orders. Incongruence length difference tests indicate that the 28S + morphological data sets are incongruent but that 28S + 18S, 18S + morphology, and 28S + 18S + morphology fail to reject the hypothesis of congruence. Phylogenetic trees were generated by parsimony analysis, and clade robustness was evaluated by branch length, Bremer support, percentage of extra steps required to force paraphyly, and sensitivity analysis using the following parameters: gap weights, morphological character weights, methods of data set combination, removal of key taxa, and alignment region. The following are monophyletic under most or all combinations of parameter values: Holometabola, Polyphaga, Megaloptera + Raphidioptera, Neuroptera, Hymenoptera, Trichoptera, Lepidoptera, Amphiesmenoptera (Trichoptera + Lepidoptera), Siphonaptera, Siphonaptera + Mecoptera, Strepsiptera, Diptera, and Strepsiptera + Diptera (Halteria). Antliophora (Mecoptera + Diptera + Siphonaptera + Strepsiptera), Mecopterida (Antliophora + Amphiesmenoptera), and Hymenoptera + Mecopterida are supported in the majority of total evidence analyses. Mecoptera may be paraphyletic because Boreus is often placed as sister group to the fleas; hence, Siphonaptera may be subordinate within Mecoptera. The 18S sequences...

The strepsipteran parasite Elenchus japonicus (Strepsiptera, Elenchidae) of planthoppers consists of three genotypes

“…The previously reported 18S rRNA gene sequence of E. japonicus (accession no. U65162; Whiting et al 1997) belonged to the AC type, and the cox1 gene sequence of E. japonicus (AY039098; Halbert et al 2001) was identical to that of the AC/mt3 type in the present study ( Supplementary Fig. 2).…”

Systematics and biology of the aberrant intertidal parasitoid wasp Echthrodesis lamorali Masner (Hymenoptera : Platygastridae s.l.): a parasitoid of spider eggs

“…PCR amplification of añ 800 bp segment of the nuclear 28S rDNA gene, spanning the D2 and D3 segments, was implemented using the primers D2-3665 F and D3-4413 R (Gillespie et al, 2005). Amplification of an~800 bp segment of the nuclear 18S rDNA gene for E. lamorali only was implemented using the primers 18Sai and 18Sbi (Whiting et al 1997). Table 1.…”

Molecular systematics of basal subfamilies of ants using 28S rRNA (Hymenoptera: Formicidae)

“…The results should identify the relative positions of the putative basal lineages of the ants. The 28S rRNA locus employed here has been used frequently to reveal phylogenetic relationships for a variety of taxonomic groups (Belshaw et al, 1998;Cameron and Mardulyn, 2001;Linares et al, 1991;Morgan et al, 2002;Sullender and Johnson, 1998;Whiting et al, 1997). The molecular sequence analysis also provides an opportunity to test how well the morphological characters used to establish the poneromorph subfamilies delineate actual phylogenetic relationships.…”