A phylogeny of anisopterous dragonflies (Insecta, Odonata) using mtRNA genes and mixed nucleotide/doublet models

Abstract

The application of mixed nucleotide ⁄ doublet substitution models has recently received attention in RNA-based phylogenetics. Within a Bayesian approach, it was shown that mixed models outperformed analyses relying on simple nucleotide models. We analysed an mt RNA data set of dragonflies representing all major lineages of Anisoptera plus outgroups, using a mixed model in a Bayesian and parsimony (MP) approach. We used a published mt 16S rRNA secondary consensus structure model and inferred consensus models for the mt 12S rRNA and tRNA valine. Secondary structure information was used to set data partitions for paired and unpaired sites on which doublet or nucleotide models were applied, respectively. Several different doublet models are currently available of which we chose the most appropriate one by a Bayes factor test. The MP reconstructions relied on recoded data for paired sites in order to account for character covariance and an application of the ratchet strategy to find most parsimonious trees. Bayesian and parsimony reconstructions are partly differently resolved, indicating sensitivity of the reconstructions to model specification. Our analyses depict a tree in which the damselfly family Lestidae is sister group to a monophyletic clade Epiophlebia + Anisoptera, contradicting recent morphological and molecular work. In Bayesian analyses, we found a deep split between Libelluloidea and a clade ÔAeshnoideaÕ within Anisoptera largely congruent with TillyardÕs early ideas of anisopteran evolution, which had been based on evidently plesiomorphic character states. However, parsimony analysis did not support a clade ÔAeshnoideaÕ, but instead, placed Gomphidae as sister taxon to Libelluloidea. Monophyly of Libelluloidea is only modestly supported, and many inter-family relationships within Libelluloidea do not receive substantial support in Bayesian and parsimony analyses. We checked whether high Bayesian node support was inflated owing to either: (i) wrong secondary consensus structures; (ii) under-sampling of the MCMC process, thereby missing other local maxima; or (iii) unrealistic prior assumptions on topologies or branch lengths. We found that different consensus structure models exert strong influence on the reconstruction, which demonstrates the importance of taxon-specific realistic secondary structure models in RNA phylogenetics.

<span lang="EN-US"><span style="font-family: 'Times New Roman'; font-size: small;">The classification and diversity of dragonflies and damselflies (Odonata). In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) </span></span>

“…30. There is general agreement that Anisoptera is monophyletic (Bechly 1996;Bybee et al 2008;Carle et al 2008;Davis et al 2011;Fleck et al 2008b;Rehn 2003). Although the major groupings are resolved, three well-defined monophyletic groups (Aeshnoidea, Gomphoidea and Petaluroidea, sometimes combined into larger clades) rotate as the sister-group of remaining anisopterans in the various published trees.…”

“…15. A tiny but distinctive family, molecular data and larvae indicate Dicteriadidae fall within the calopterygoid complex (Dumont et al 2010;Fleck et al 2008b;. 16.…”

“…28. Epiophlebia is accepted as the extant sister-group of 'true' Anisoptera (Bechly 1996;Bybee et al 2008;Davis et al 2011;Fleck et al 2008b;Rehn 2003). The genus has traditionally been placed in the suborder Anisozygoptera, although the initial usage of that name was for fossil taxa.…”

Musculoskeletal modelling under an evolutionary perspective: deciphering the role of single muscle regions in closely related insects

“…In Libellulidae, a family consistently recovered as a derived group [57,58,61,62], additional medial muscle groups are very small or even absent [7], consequently also leading to a lower bite force [10]. It remains to be tested on a larger sample of dragonflies which factors are mainly influencing the evolution of the mandibular muscle system.…”

“…For example, Aeshna and Anax are both members of the Aeshnidae, a dragonfly family presumed to represent an early split within dragonflies [57,58], and they both showed largely similar activity time series. However, the subapical muscle groups showed only a distinctly higher activity in Onychogomphus, whereas in Anax and Cordulegaster subapical muscle groups did not show such a distinct pattern ( figure 3b,c).…”