Relationships among the major lineages of Dictyoptera: the effect of outgroup selection on dictyopteran tree topology

Abstract

Dictyoptera, comprising Blattaria, Isoptera, and Mantodea, are diverse in appearance and life history, and are strongly supported as monophyletic. We downloaded COII, 16S, 18S, and 28S sequences of 39 dictyopteran species from GenBank. Ribosomal RNA sequences were aligned manually with reference to secondary structure. We included morphological data (maximum of 175 characters) for 12 of these taxa and for an additional 15 dictyopteran taxa (for which we had only morphological data). We had two datasets, a 59-taxon dataset with five outgroup taxa, from Phasmatodea (2 taxa), Mantophasmatodea (1 taxon), Embioptera (1 taxon), and Grylloblattodea (1 taxon), and a 62-taxon dataset with three additional outgroup taxa from Plecoptera (1 taxon), Dermaptera (1 taxon) and Orthoptera (1 taxon). We analysed the combined molecularÀ morphological dataset using the doublet and MK models in MRBAYES, and using a parsimony heuristic search in PAUP. Within the monophyletic Mantodea, Mantoida is recovered as sister to the rest of Mantodea, followed by Chaeteessa; the monophyly of most of the more derived families as defined currently is not supported. We recovered novel phylogenetic hypotheses about the taxa within Blattodea (following Hennig, containing Isoptera). Unique to our study, one Bayesian analysis places Polyphagoidea as sister to all other Dictyoptera; other analyses and/or the addition of certain orthopteran sequences, however, place Polyphagoidea more deeply within Dictyoptera. Isoptera falls within the cockroaches, sister to the genus Cryptocercus. Separate parsimony analyses of independent gene fragments suggest that gene selection is an important factor in tree reconstruction. When we varied the ingroup taxa and/or outgroup taxa, the internal dictyopteran relationships differed in the position of several taxa of interest, including Cryptocercus, Polyphaga, Periplaneta and Supella. This provides further evidence that the choice of both outgroup and ingroup taxa greatly affects tree topology.

Molecular phylogeny of Blaberidae (Dictyoptera, Blattodea) with implications for taxonomy and evolutionary studies

“…Saturation plots and analyses of bias in nucleotide composition should be performed with phylogenetic informativeness and network analyses (Huson & Bryant 2006;Townsend 2007;Philippe & Roure 2011). Also, given the long branches in the putative sister group Pseudophyllodromiinae (Legendre et al 2015) and the results of our preliminary analyses and of previous studies on the effect of outgroup choice on tree reconstruction in Dictyoptera (Ware et al 2008;Djernaes et al 2012), the impact of outgroup choice in the phylogenetics of Blaberidae should be investigated further. Analyzing these conflicting signals and their causes remains, however, a complicated task, so cockroach phylogenetics would above all else benefit from new appropriate markers that are now reachable with the development of next generation sequencing methods (Metzker 2010).…”

The phylogenetic system of Mantodea (Insecta: Dictyoptera)

“…The assumed monophyly of Mantodea is well supported by morphological characters (Hennig 1969(Hennig , 1981Ax 1999;Klass 1995Klass , 1997Deitz et al 2003;Klass & Meier 2006;Klass & Eulitz 2007;Ware et al 2008;Klass et al 2009) and molecular data (Svenson & Whiting 2003, 2004aTerry & Whiting 2005;Kjer et al 2006;Inward et al 2007;Lo et al 2007;Fenn et al 2008;Ware et al 2008;Yager & Svenson 2008). Klass & Ehrmann (2003: 196) listed the following autapomorphies for Mantodea.…”

“…Hennig 1969Hennig , 1981Kristensen 1975Kristensen , 1981Kristensen , 1991Kristensen , 1995Klass 1995Klass , 1997Klass , 1998aKlass , b, 2003aWheeler 1998;Maekawa et al 1999;Wheeler et al 2001a, b;Deitz et al 2003;Grimaldi 2003;Whiting et al 2003;Willmann 2003aWillmann , b, 2004Kjer 2004;Grimaldi & Engel 2005;Jarvis et al 2005;Terry & Whiting 2005;Kjer et al 2006;Klass & Meier 2006;Wieland 2006;Inward et al 2007;Lo et al 2007;Fenn et al 2008;Grimaldi 2008;Ware et al 2008; Klass et al 2009) and is undoubted.…”

“…7.60). Roy (1999: 37) Morphological and several molecular datasets have repeatedly found Mantoida to be the sistergroup of the remaining extant Mantodea (Klass 1995(Klass , 1997Svenson & Whiting 2004a;Klass & Meier 2006;Inward et al 2007;Lo et al 2007;Ware et al 2008;Yager & Svenson 2008). Jantsch (1999) found a basal split between a monophyletic Mantoida + Chaeteessa and the remaining (predominantly Neotropical) Mantodea in his morphological analysis.…”

“…Together with Blattodea (cockroaches with the termites being nested among them as the sistergroup of Cryptocercus Scudder, 1862, see for instance Hennig 1969Hennig , 1981Inward et al 2007; Klass et al 2008;Ware et al 2008), Mantodea form the Dictyoptera, a subordinate taxon of Polyneoptera sensu Martynov (1925: 497; the monophyly of Polyneoptera is still debated, The biology of Mantodea as a whole or of single taxa was treated, among many others, by Shelford (1903Shelford ( , 1916, Handlirsch (1925Handlirsch ( , 1930a, Beier & Jaus (1933), Roberts (1937a, b), Chopard (1938Chopard ( , 1949a, Beebe et al (1952), Lieftinck (1953), Kaltenbach (1963), Beier (1964a, 1968a, Brown (1982), Ramsay (1990), Balderson (1991), Rentz (1996), , Ehrmann (2001aEhrmann ( , b, 2002, Neumann (2006), Schwarz et al (2006Schwarz et al ( , 2007, Delfosse et al (2007), Heßler et al (2008) and Wieland (2008a). Morphological and anatomical studies or synopses were published, for instance, by Levereault (1936Levereault ( , 1938, Strenger (1942), Chopard (1949a, La Greca & Rainone (1949), La Greca & Raucci (1949), Smart (1956), …”