Coding characters from different life stages for phylogenetic reconstruction: a case study on dragonfly adults and larvae, including a description of the larval head anatomy ofEpiophlebia superstes(Odonata: Epiophlebiidae)

Abstract

The exclusive use of characters coding for specific life stages may bias tree reconstruction. If characters from several life stages are coded, the type of coding becomes important. Here, we simulate the influence on tree reconstruction of morphological characters of Odonata larvae incorporated into a data matrix based on the adult body under different coding schemes. For testing purposes, our analysis is focused on a well-supported hypothesis: the relationships of the suborders Zygoptera, 'Anisozygoptera', and Anisoptera. We studied the cephalic morphology of Epiophlebia, a key taxon among Odonata, and compared it with representatives of Zygoptera and Anisoptera in order to complement the data matrix. Odonate larvae are characterized by a peculiar morphology, such as the specific head form, mouthpart configuration, ridge configuration, cephalic musculature, and leg and gill morphology. Four coding strategies were used to incorporate the larval data: artificial coding (AC), treating larvae as independent terminal taxa; non-multistate coding (NMC), preferring the adult life stage; multistate coding (MC); and coding larval and adult characters separately (SC) within the same taxon. As expected, larvae are 'monophyletic' in the AC strategy, but with anisopteran and zygopteran larvae as sister groups. Excluding larvae in the NMC approach leads to strong support for both monophyletic Odonata and Epiprocta, whereas MC erodes phylogenetic signal completely. This is an obvious result of the larval morphology leading to many multistate characters. SC results in the strongest support for Odonata, and Epiprocta receives the same support as with NMC. Our results show the deleterious effects of larval morphology on tree reconstruction when multistate coding is applied. Coding larval characters separately is still the best approach in a phylogenetic framework.

The head morphology of Pyrrhosoma nymphula larvae (Odonata: Zygoptera) focusing on functional aspects of the mouthparts

“…Furthermore, there is a shift of the origin point of the muscle 0an5 from the frons to the tentorium – 0an5 might take over the function of 0an7 – we follow the suggested homologization from Blanke et al [9]. …”

Three-dimensional reconstruction on cell level: case study elucidates the ultrastructure of the spinning apparatus of Embia sp. (Insecta: Embioptera)

“…[31] established this technique in insect morphology in 2002. µCT combines user friendliness with powerful computational applications to study small- to medium-sized insects. Meanwhile, there are numerous comprehensive studies investigating each tagma of insects: insect head [32,33], insect thorax [27,34], insect abdomen [35,36] and even smaller body parts [5,37]. The advantages of μCT are that it is non-invasive, comparatively rapid, almost free of artefacts, and allow for a three-dimensional reconstruction at convenient nanotomographical resolutions less than 0.1 µm [21] depending on the set-up used for data acquisition.…”

The phylogenetic relevance of thoracic musculature: a case study including a description of the thorax anatomy of Zygoptera (Insecta: Odonata) larvae

“…Morphological characters derived from the larval stage of Odonata have been shown to provide phylogenetic signal for Odonata phylogenetics (e.g. Fleck, , ) and can be excellent phylogenetic characters (Blanke et al ., ).…”

“…between family groups) within Odonata are still largely unresolved (e.g. von Ellenrieder, ; Rehn, ; Bybee et al ., ; Fleck et al ., ; Dijkstra et al ., ; Blanke et al ., , ; Carle et al ., ). Wing characters are the most common source of morphological data for phylogenetic reconstructions among Odonata (Trueman, ; Rehn, ; Bybee et al ., ).…”

“…the insect head, have repeatedly been shown to be an important source of phylogenetic information (e.g. Beutel et al ., ; Wipfler et al ., ; Blanke et al ., , ). Arising >320 million years ago, flight is one of the major innovations in the evolutionary history of insects (e.g.…”