The Palaeoptera Problem: Basal Pterygote Phylogeny Inferred from 18S and 28S rDNA Sequences

Abstract

Monophyly of the pterygote insects is generally accepted, but the relationships among the three basal branches (Odonata, Ephemeroptera and Neoptera) remain controversial. The traditional view, to separate the pterygote insects in Palaeoptera (Odonata + Ephemeroptera) and Neoptera, based on the ability or inability to fold the wings over the abdomen, has been questioned. Various authors have used different sets of morphological characters in support of all three possible arrangements of the basal pterygote branches. We sequenced 18S and 28S rDNA from 18 species of Odonata, 8 species of Ephemeroptera, 2 species of Neoptera, and 1 species of Archaeognatha in our study. The new sequences, in combination with sequences from GenBank, have been used in a parsimony jackknife analysis resulting in strong support for a monophyletic Palaeoptera. Morphological evidence and the phylogenetic implications for understanding the origin of insect flight are discussed.

Phylogeographic Analysis Elucidates the Influence of the Ice Ages on the Disjunct Distribution of Relict Dragonflies in Asia

“…These results contradict the widely accepted hypothesis of a monophyletic Anisoptera and a recently published hypothesis based on more comprehensive datasets proposing a sistergroup relationship between Epiophlebia and Anisoptera [8]–[11]. However, in the maximum likelihood analysis (Figure 2B) a sistergroup relationship of Epiophlebia and a clade containing Anisoptera with the exception of Aeshnidae is recovered.…”

“…Taxa for the analysis were originally selected to represent major clades from the phylogenetic system of Odonata as reconstructed in [8] and we expected to recover its general topology. However, our taxon sample is not as comprehensive as in any of the investigations that recently confirmed monophyletic Anisoptera with a sistergroup Epiophlebia [6], [8], [10], [11]. Therefore, the differing topology found in the present analysis may well be attributed to effects of the composition of taxa in the dataset.…”

“…Presently, Epiophlebia is considered to be the most basal sistergroup of the Anisoptera, with several extinct lineages nested in between [4]–[7]. A close relationship of Anisoptera and Epiophlebia has also been corroborated by several molecular analyses and the term Epiprocta has been introduced for this grouping [8]–[11].…”

The thorax musculature of Anisoptera (Insecta: Odonata) nymphs and its evolutionary relevance

“…This grouping is based mainly on the inability of the groups comprised by Palaeoptera to fold their wings above the abdomen and the similarity of the wing base sclerites [30-39]. In addition, DNA [27,40] and recent morphology-based analyses [28,29,41] also support the Palaeoptera hypothesis. The second hypothesis proposes Odonata and Neoptera as sistergroups under the name Metapterygota.…”

Insights into the molecular mechanisms underlying diversified wing venation among insects

“…Acquisition of flight enabled insects to exploit new habitats and escape from unfavourable environments. It is accepted that wings arose once in the insect lineage, as evidenced by the winged group (Pterygota) being monophyletic [1][2][3][4][5]. The winged insects consist of Paleoptera (the basal winged groups, Ephemeroptera and Odonata) and Neoptera.…”