A phylogenetic study of the 'bombycoid complex' (Lepidoptera) using five protein-coding nuclear genes, with comments on the problem of macrolepidopteran phylogeny

Abstract This study had two aims. First, we tested the monophyly of and relationships within the ‘bombycoid complex’, an assembly of approximately 5300 species postulated by Minet to represent 12 families in three superfamilies, by sequencing five protein‐coding nuclear gene regions (CAD, DDC, enolase, period, wingless; approximately 6750 bp total) in 66 representatives of most of the subfamilies and tribes. Second, we sought initial evidence on the utility of these genes for estimating relationships among Macrolepidoptera more broadly (11 superfamilies total), by adding representatives of eight families from four other superfamilies, and by assessing the phylogenetic information content of the individual genes and partitions thereof. Analysis of the combined data by likelihood and parsimony upholds monophyly for the bombycoid complex and for Bombycoidea sensu stricto (includes Anthelidae, see below), but with weak bootstrap support. Minet’s assignment of Phiditiinae to Bombycoidea rather than to Noctuoidea is strongly upheld, but Anthelidae, placed in Lasiocampoidea by Minet, group securely within Bombycoidea sensu stricto. Within the latter, the basal split segregates a strongly supported ‘BALE’ group [Apatelodinae + (Eupterotidae + (Brahmaeidae + Lemoniidae))]. The remaining families form a consistently but weakly supported clade, within which the basal split segregates the very strongly supported ‘CAPOPEM’ group [Carthaeidae, Anthelidae, Phiditiinae, (Prismostictini + (Endromidae + (Oberthueriini + Mirinidae)))]. The remaining bombycoids are grouped, very weakly, as Sphingidae + (Bombycinae + Saturniidae). All multiply‐sampled families are strongly recovered, in both outgroups and ingroups, except that Bombycidae sensu Minet are rendered decisively polyphyletic. All genes make important contributions to the combined data results, and there is little strong conflict among genes or between synonymous and nonsynonymous change, although two instances of inter‐gene conflict were notable, one in Lasiocampidae and one in Mimallonidae. Overall, about 75% of nodes are strongly supported (i.e. bootstrap value ≥80%). Superfamilies are recovered, but not always strongly, whereas relationships among superfamilies are recovered only weakly and inconsistently; even within the reasonably well‐sampled Bombycoidea sensu stricto, a (to us) surprising number of interfamily relationships remain uncertain. Thus, it seems clear that substantially more genes, plus additional taxon sampling in most superfamilies, will be required to resolve macrolepidopteran phylogeny.     

Increased gene sampling yields robust support for higher‐level clades within Bombycoidea (Lepidoptera)

This study has as its primary aim the robust resolution of higher‐level relationships within the lepidopteran superfamily Bombycoidea. Our study builds on an earlier analysis of five genes (～6.6 kbp) sequenced for 50 taxa from Bombycoidea and its sister group Lasiocampidae, plus representatives of other macrolepidoteran superfamilies. The earlier study failed to yield strong support for the monophyly of and basal splits within Bombycoidea, among others. Therefore, in an effort to increase support specifically for higher‐level nodes, we generated 11.7 kbp of additional data from 20 genes for 24 of 50 bombycoid and lasiocampid taxa. The data from the genes are all derived from protein‐coding nuclear genes previously used to resolve other lepidopteran relationships. With these additional data, all but a few higher‐level nodes are strongly supported. Given our decision to minimize project costs by augmenting genes for only 24 of the 50 taxa, we explored whether the resulting pattern of missing data in the combined‐gene matrix introduced a nonphylogenetic bias, a possibility reported by others. This was achieved by comparing node support values (i.e. nonparametric bootstrap values) based on likelihood and parsimony analyses of three datasets that differ in their number of taxa and level of missing data: 50 taxa/5 genes (dataset A), 50 taxa/25 genes (dataset B) and 24 taxa/25 genes (dataset C). Whereas datasets B and C provided similar results for common nodes, both frequently yielded higher node support relative to dataset A, arguing that: (i) more data yield increased node support and (ii) partial gene augmentation does not introduce an obvious nonphylogenetic bias. A comparison of single‐gene bootstrap analyses identified four nodes for which one or two of the 25 genes provided modest to strong support for a grouping not recovered by the combined‐gene result. As a summary proposal, two of these four groupings (one each within Bombycoidea and Lasiocampidae) were deemed sufficiently problematic to regard them as unresolved trichotomies. Since the alternative groupings were always highly localized on the tree, we did not judge a combined‐gene analysis to present a problem outside those regions. Based on our robustly resolved results, we have revised the classification of Bombycoidea: the family Bombycidae is restricted to its nominate subfamily, and its tribe Epiini is elevated to subfamily rank (Epiinae stat.rev. ), whereas the bombycid subfamily Phiditiinae is reinstated as a separate family (Phiditiidae stat.rev. ). The bombycid subfamilies Oberthueriinae Kuznetzov & Stekolnikov, 1985, syn.nov. and Prismostictinae Forbes, 1955, syn.nov. , and the family Mirinidae Kozlov, 1985, syn.nov. are established as subjective junior synonyms of Endromidae Boisduval, 1828. The family Anthelidae (Lasiocampoidea) is reincluded in the superfamily Bombycoidea.     

Molecular phylogeny of Anthelidae and other bombycoid taxa (Lepidoptera: Bombycoidea)

Abstract.  Based on DNA sequences of the fusion protein carbamoylphosphate synthetase/aspartate transcarbamylase/dihydroorotase (CAD; 680 bp) and elongation factor-1α (Ef-1α; 1240 bp); the first molecular phylogeny of the moth family Anthelidae and its placement within the Bombycoidea sensu Brock (1971) (= bombycoid complex sensu Minet, 1994 ) is proposed. The results strongly support the monophyly of the family Anthelidae and its subfamilies Munychryiinae and Anthelinae, but demonstrate the vast polyphyly of its main genus Anthela Walker, 1855. The proposed phylogeny suggests that grass feeding, as apparent from some pest records, probably is an ancestral trait within the subfamily Anthelinae. Evolutionary relationships of the family Anthelidae and of most parts of the Bombycoidea remain obscure. However, the results contradict many of the widely accepted phylogenetic hypotheses within the Bombycoidea proposed by Minet (1994 : Entomologica scandinavica , 25, 63–88). The Brahmaeidae are paraphyletic relative to the Lemoniidae ( syn.nov. ), and the current concept of Bombycidae is polyphyletic, with the bombycid subfamily Apatelodinae being part of a monophylum comprising Brahmaeidae / Lemoniidae, Eupterotidae and Apatelodidae ( stat.rev .).     

Complete mitochondrial genome of Saturnia jonasii (Lepidoptera: Saturniidae): Genomic comparisons and phylogenetic inference among Bombycoidea

The complete mitochondrial genome (mitogenome) of Saturnia jonasii (Lepidoptera: Saturniidae) was sequenced and compared to those of 19 other bombycoid species. Furthermore, the mitogenome sequences were used to infer phylogenetic relationships among bombycoid species. The 15,261-bp Saturnia jonasii mitogenome contained the typical sets of genes and gene arrangements found in majority of Lepidoptera. All Bombycoidea species, including Saturnia jonasii, have a 15–33-bp spacer sequence at the trnS₂-ND1 junction. The phylogenetic reconstruction of bombycoid species consistently and strongly supported monophylies of the families, Saturniidae, Bombycidae, and Sphingidae, based on Bayesian inference (BI) and maximum-likelihood (ML) methods. Among these families, the Bombycidae and Sphingidae species consistently showed a sister relationship, regardless of data partitions; the BI method strongly supported this relationship, whereas it was moderately supported using the ML method.     

The mitochondrial genome of the butterfly Papilio xuthus (Lepidoptera: Papilionidae) and related phylogenetic analyses

The nearly complete mitochondrial genome of the butterfly Papilio xuthus (Lepidoptera: Papilionidae) was sequenced for its nucleotide sequence of 13,964 bp. The genome has a typical gene order identical to other lepidopteran species. All tRNAs showed same stable canonical clover-leaf structure as those of other insects, except for tRNA^Ser (AGN), in which the dihydrouracil arm (DHU arm) could not form stable stem–loop structure. Anomalous initiation codons have been observed for the cox1 gene, where the ATTACG hexa-nucleotide was believed to be involved in the initiation signaling. Twelve mitochondrial protein-coding gene sequence data were used to infer the phylogenetic relationships among the insect orders. Even though the number of insect orders represented by complete mitochondrial genomes is still limited, several well-established relationships are evident in the phylogenetic analysis of the complete sequences. Monophyly of the Homometabola was not supported in this paper. Phylogenetic analyses of the available species of Bombycoidea, Pyraloidea, Papilionoidea and Tortricidea bolstered the current morphology-based hypothesis that Bombycoidea, Pyraloidea and Papilionoidea are monophyletic (Obtectomera). Bombycoidea (Bombyx mandarina and Antheraea pernyi) and Papilionoidea (P. xuthus and Coreana raphaelis) formed a sister group.     

The first mitochondrial genome for Brahmin moths (Brahmaeidae) and implications for the higher phylogeny of Bombycoidea

Bombycoidea comprises 10 families and 4723 species, and the phylogenetic relationships among families are still in debate. In this study, we have determined the complete mitochondrial genome (mitogenome) of Brahmaea porphyria. The 15,429-bp mitogenome contains a common set of 37 mitochondrial genes including 13 protein-coding genes, 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and an inferred control region, and shares the conserved gene rearrangement (trnM-trnI-trnQ) in most ditrysian mitogenomes. Moreover, we analysed the secondary structure for all the tRNA genes of B. porphyria and the preference of codon usage in the PCGs of B. porphyria. The putative 373-bp control region (CR) possesses three types of conserved elements, including ATAGA, Ploy-T stretch, and microsatellite-like elements. A phylogenetic analysis among available Bombycoidea mitogenomes using the concatenated 37 mitochondrial genes appears to support the hypothesis of (Sphingidae+Bombycidae)+Saturniidae and the relatively basal phylogenetic position of Brahmaeidae within Bombycoidea.     

Reconstructing intraordinal relationships in Lepidoptera using mitochondrial genome data with the description of two newly sequenced lycaenids, Spindasis takanonis and Protantigius superans (Lepidoptera: Lycaenidae)

Lepidoptera is one of the largest insect orders, but the phylogenetic relationships within this order, have yet to be adequately described. Among these unresolved relationships include those regarding the monophyly of the Macrolepidoptera and interfamilial relationships of the true butterflies superfamily Papilionoidea. We present two new mitochondrial genomes (mitogenomes) belonging to the butterfly family Lycaenidae to explore the phylogenetic relationships existing among lepidopteran superfamilies and true butterfly families from a mitogenome perspective, and to evaluate the characteristics of the lepidopteran mitogenomes. Our consensus phylogeny of the Lepidoptera largely supported the superfamilial relationships (((((Bombycoidea + Geometroidea) + Noctuoidea) + Pyraloidea) + Papilionoidea) + Tortricoidea), signifying a lack of support for a traditionally defined Macrolepidoptera. The familial relationships of the true butterflies concordantly recovered the previously proposed phylogenetic hypothesis (((Lycaenidae + Nymphalidae) + Pieridae) + Papilionidae). The test for the effect of optimization schemes (exclusion and inclusion of third codon position of PCGs and two rRNA genes, with and without partitions) on the resolution and relationships within the Lepidoptera have demonstrated that the majority of analyses did not substantially alter the relevant topology and node support, possibly as the result of relatively strong signal in mitogenomes for intraordinal relationships in Lepidoptera.     

九种绢丝昆虫线粒体12S rRNA基因的序列特征和系统发育分析

为探讨鳞翅目中绢丝昆虫之间的系统发育关系和分子进化特征,本研究测定了中国柞蚕Antheraea pernyi野生型和放养型的线粒体12S rRNA基因的部分序列,结合来自GenBank数据库的17条序列,对总共9种绢丝昆虫（2科3属）的12S rRNA基因序列进行了分析。利用软件MEGA 3.1进行碱基组成、变异位点的统计和分子进化分析,分别用类平均聚类法（UPGMA）、邻接法（NJ）、最小进化法（ME）、最大简约法（MP）重建系统发生树。测定的中国柞蚕野生型的12S rRNA基因序列（427 bp）与放养型“豫早1号”的序列完全一致。序列对齐后共鉴定80个变异位点,50个简约信息位点。碱基组成分析显示在科属间具有明显差异,AT含量蚕蛾科高于大蚕蛾科;在A和T碱基的使用上,大蚕蛾科偏好使用T,而蚕蛾科则偏好使用A。与动物中常见的以转换为主的碱基替换模式不同,所分析的9种昆虫中除桑蚕属内部为转换与颠换基本一致外,其余物种间均是颠换多于转换。进化分析支持柞蚕属、樗蚕属和桑蚕属的单系。基于UPGMA法的进化树支持琥珀蚕是柞蚕属的较原始类型,而NJ、ME和MP法则支持印度柞蚕是较原始的类型,因此,柞蚕属种间的进化关系尚需进一步研究。     

Mitochondrial genome sequences effectively reveal deep branching events in aphids (Insecta: Hemiptera: Aphididae)

Over the past dozen years, considerable effort has been devoted to unravelling the higher‐level phylogenetic relationships of viviparous aphids (Aphididae). However, to date, there is still no commonly accepted phylogenetic hypothesis. In this study, we establish a robust phylogenetic framework for the Aphididae based on mitochondrial genome sequences of 35 aphid species, 22 of which are newly reported. Phylogenetic inferences are performed using multiple data sets, alternative partitioning schemes and different model‐based methods. Our analyses result in well‐supported backbone relationships for the major lineages of aphids, suggesting the feasibility of mitogenome data for resolving phylogenetic questions in aphids. Mindarinae is strongly supported as the earliest branching lineage within Aphididae. A monophyletic clade comprising Calaphidinae, Phyllaphidinae and Saltusaphidinae is corroborated to be the sister group to the species‐richest subfamily Aphidinae. In addition, the morphologically defined subfamily Eriosomatinae is uncovered to be non‐monophyletic.     

Exploring taxonomic diversity and biogeography of the family Nemacheilinae (Cypriniformes)

Nemacheilidae, in the superfamily Cobitoidea, is comprised of many of morphologically similar fish species that occur in Eurasian water bodies. This large group shows inconsistencies between traditional morphological taxonomy and molecular phylogenetic data. We used mitochondrial genomes, recombinase‐activating gene proteins 1 (RAG1) and the mitochondrial cytochrome c oxidase I gene (COI) to study the phylogenetic relationships among Nemacheilidae species using Bayesian inference and maximum likelihood approaches. Phylogenetic analyses based on mitogenomes provided support for two clades (I and II). The mitogenomes, RAG1, and COI results indicated that several species and genera were not consistent with the traditional morphological subdivisions. The two clades inferred from mitogenomes showed clear geographical patterns. The Tibetan Plateau, Hengduan Mountains, and the Iran Plateau may act as a barrier dividing the clades. The estimated timing of clades separation (36.05 million years ago) coincides with the first uplift of the Tibetan Plateau. We conclude that the geological history of the Tibetan Plateau played a role in the diversification and distribution of the Nemacheilidae taxa. These results provided a phylogenetic framework for future studies of this complex group.     

The complete mitochondrial genomes of six heterodont bivalves (Tellinoidea and Solenoidea): variable gene arrangements and phylogenetic implications

Background

Taxonomy and phylogeny of subclass Heterodonta including Tellinoidea are long-debated issues and a complete agreement has not been reached yet. Mitochondrial (mt) genomes have been proved to be a powerful tool in resolving phylogenetic relationship. However, to date, only ten complete mitochondrial genomes of Heterodonta, which is by far the most diverse major group of Bivalvia, have been determined. In this paper, we newly sequenced the complete mt genomes of six species belonging to Heterodonta in order to resolve some problematical relationships among this subclass.

Principal Findings

The complete mt genomes of six species vary in size from 16,352 bp to 18,182. Hairpin-like secondary structures are found in the largest non-coding regions of six freshly sequenced mt genomes, five of which contain tandem repeats. It is noteworthy that two species belonging to the same genus show different gene arrangements with three translocations. The phylogenetic analysis of Heterodonta indicates that Sinonovacula constricta, distant from the Solecurtidae belonging to Tellinoidea, is as a sister group with Solen grandis of family Solenidae. Besides, all five species of Tellinoidea cluster together, while Sanguinolaria diphos has closer relationship with Solecurtus divaricatus, Moerella iridescens and Semele scaba rather than with Sanguinolaria olivacea.

Conclusions/Significance

By comparative study of gene order rearrangements and phylogenetic relationships of the five species belonging to Tellinoidea, our results support that comparisons of mt gene order rearrangements, to some extent, are a useful tool for phylogenetic studies. Based on phylogenetic analyses of multiple protein-coding genes, we prefer classifying the genus Sinonovacula within the superfamily Solenoidea and not the superfamily Tellinoidea. Besides, both gene order and sequence data agree that Sanguinolaria (Psammobiidae) is not monophyletic. Nevertheless, more studies based on more mt genomes via combination of gene order and phylogenetic analysis are needed to further understand the phylogenetic relationships in subclass Heterodonta.     

Complete nucleotide sequence and organization of the mitogenome of the silk moth Caligula boisduvalii (Lepidoptera: Saturniidae) and comparison with other lepidopteran insects

The 15,360-bp long complete mitogenome of Caligula boisduvalii possesses a gene arrangement and content identical to other completely sequenced lepidopteran mitogenomes, but different from the common arrangement found in most insect order, as the result of the movement of tRNA(Met) to a position 5'-upstream of tRNA Ile. The 330-bp A+T-rich region is apparently capable of forming a stem-and-loop structure, which harbors the conserved flanking sequences at both ends. Dissimilar to what has been seen in other sequenced lepidopteran insects, the initiation codon for C. boisduvalii COI appears to be TTG, which is a rare, but apparently possible initiation codon. The ATP8, ATP6, ND4L, and ND6 genes, which neighbor another PCG at their 3' end, all harbored potential sequences for the formation of a hairpin structure. This is suggestive of the importance of such structures for the precise cleavage of the mRNA of mature PCGs. Phylogenetic analyses of available sequenced species of Bombycoidea, Pyraloidea, and Tortricidea supported the morphology-based current hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As previously suggested, Bombycidae (Bombyx mori and B. mandarina) and Saturniidae (Antheraea pernyi and C. boisduvalii) formed a reciprocal monophyletic group.     

Molecular phylogeny of Pamphagidae (Acridoidea,Orthoptera) from China based on mitochondrial cytochrome oxidase II sequences

Abstract Phylogenetic relationships of Pamphagidae were examined using cytochrome oxidase subunit II (COII) mtDNA sequences (684 bp). Twenty‐seven species of Acridoidea from 20 genera were sequenced to obtain mtDNA data, along with four species from the GenBank nucleotide database. The purpose of this study was analyzing the phylogenetic relationships among subfamilies within Pamphagidae and interpreting the phylogenetic position of this family within the Acridoidea superfamily. Phylogenetic trees were reconstructed using neighbor‐joining (NJ), maximum parsimony (MP) and Bayesian inference (BI) methods. The 684 bp analyzed fragment included 126 parsimony informative sites. Sequences diverged 1.0%–11.1% between genera within subfamilies, and 8.8%–12.3% between subfamilies. Amino acid sequence diverged 0–6.1% between genera within subfamilies, and 0.4%–7.5% between subfamilies. Our phylogenetic trees revealed the monophyly of Pamphagidae and three distinct major groups within this family. Moreover, several well supported and stable clades were found in Pamphagidae. The global clustering results were similar to that obtained through classical morphological classification: Prionotropisinae, Thrinchinae and Pamphaginae were monophyletic groups. However, the current genus Filchnerella (Prionotropisinae) was not a monophyletic group and the genus Asiotmethis (Prionotropisinae) was a sister group of the genus Thrinchus (Thrinchinae). Further molecular and morphological studies are required to clarify the phylogenetic relationships of the genera Filchnerella and Asiotmethis.     

Taxonomy and biogeography of Diapensia (Diapensiaceae) based on chloroplast genome data

Diapensia L. is the second largest genus of Diapensiaceae. The taxonomic treatment within Diapensia and relationships within Diapensiaceae have been disputed. Chloroplast genome sequence data have proved to be useful for plant phylogenetic analyses and species delimitation. In this study, we de novo sequenced and assembled 22 chloroplast genomes of 15 species of Diapensiaceae, including all recognized species of Diapensia with multiple samples. A super‐matrix containing a total of 107 genes and 18 taxa was constructed for phylogenetic analyses to resolve phylogenetic relationships among genera of the family and within Diapensia. The resulting phylogenetic tree showed the following strongly supported relationships: (Galax, (Pyxidanthera, (Berneuxia, ((Schizocodon, Diapensia), and Shortia s.s.)))). The dated phylogeny and reconstructed lineage‐through‐time plot for the family indicated rapid diversification in the Neogene and an acceleration of diversification rate after c. 8 Ma. Biogeographic analysis suggested that Diapensia originated in the Northeast Asian mountains approximately 6.06 Ma, followed by northward dispersal to the Arctic and southwestward dispersal to the Himalaya–Hengduan Mountains. Phylogenetic relationships within Diapensia were well resolved. Based on the phylogenetic results, we proposed to reinstate the species status of Diapensia bulleyana Forrest ex Diels, and raised D. purpurea f. albida to the species rank (D. albida [W. E. Evans] J. F. Ye comb. & stat. nov.). The distribution ranges of all species delineated based on the phylogenetic results were revised accordingly based on specimen occurrences. Our study adds new examples for the power of plastid genome data for resolving phylogenetic relationships and clarifying taxonomic disputes among closely related species.     

Molecular phylogeny and systematics of Dipodoidea: a test of morphology‐based hypotheses

Lebedev, V.S., Bannikova, A.A., Pagès, M., Pisano, J., Michaux, J.R. & Shenbrot, G.I. (2012). Molecular phylogeny and systematics of Dipodoidea: a test of morphology‐based hypotheses. —Zoologica Scripta, 42, 231–249. The superfamily Dipodoidea (Rodentia, Myomorpha) in its current interpretation contains a single family subdivided into six subfamilies. Four of them include morphologically specialized bipedal arid‐dwelling jerboas (Dipodinae – three‐toed jerboas, Allactaginae – five‐toed jerboas, Cardiocraniinae – pygmy jerboas and Euchoreutinae – long‐eared jerboas), the other two are represented by more generalized quadrupedal taxa (Zapodinae – jumping mice and Sminthinae – birch mice). Despite considerable effort from morphologists, the taxonomy as well as the phylogeny of the Dipodoidea remains controversial. Strikingly, molecular approach has never been envisaged to investigate these questions. In this study, the phylogenetic relationships among the main dipodoid lineages were reconstructed for the first time using DNA sequence data from four nuclear genes (IRBP, GHR, BRCA1, RAG1). No evidence of conflict among genes was revealed. The same robustly supported tree topology was inferred from the concatenated alignment whatever the phylogenetic methods used (maximum parsimony, maximum‐likelihood and Bayesian phylogenetic methods). Sminthinae branches basally within the dipodoids followed by Zapodinae. Monophyletic Cardiocraniinae is sister to all other jerboas. Within the latter, the monophyly of both Dipodinae and Allactaginae is highly supported. The relationships between Dipodinae, Allactaginae and Euchoreutinae should be regarded as unresolved trichotomy. Morphological hypotheses were confronted to findings based on the presented molecular data. As a result, previously proposed sister group relationships between Euchoreutes and Sicista, Paradipus and Cardiocraniinae as well as the monophyly of Cardiocaniinae + Dipodinae were rejected. However, the latter association is consistently supported by most morphological analyses. The basis of the obvious conflict between genes and morphology remains unclear. Suggested modifications to the taxonomy of Dipodoidea imply recognition of three families: Sminthidae, Zapodidae and Dipodidae, the latter including Cardiocraniinae, Euchoreutinae, Allactaginae and Dipodinae as subfamilies.     

Mitochondrial phylogenomics and genetic relationships of closely related pine moth (Lasiocampidae: Dendrolimus) species in China,using whole mitochondrial genomes

Background

Pine moths (Lepidoptera; Bombycoidea; Lasiocampidae: Dendrolimus spp.) are among the most serious insect pests of forests, especially in southern China. Although COI barcodes (a standardized portion of the mitochondrial cytochrome c oxidase subunit I gene) can distinguish some members of this genus, the evolutionary relationships of the three morphospecies Dendrolimus punctatus, D. tabulaeformis and D. spectabilis have remained largely unresolved. We sequenced whole mitochondrial genomes of eight specimens, including D. punctatuswenshanensis. This is an unambiguous subspecies of D. punctatus, and was used as a reference for inferring the relationships of the other two morphospecies of the D. punctatus complex. We constructed phylogenetic trees from this data, including twelve published mitochondrial genomes of other Bombycoidea species, and examined the relationships of the Dendrolimus taxa using these trees and the genomic features of the mitochondrial genome.

Results

The eight fully sequenced mitochondrial genomes from the three morphospecies displayed similar genome structures as other Bombycoidea species in terms of gene content, base composition, level of overall AT-bias and codon usage. However, the Dendrolimus genomes possess a unique feature in the large ribosomal 16S RNA subunits (rrnL), which are more than 60 bp longer than other members of the superfamily and have a higher AC proportion. The eight mitochondrial genomes of Dendrolimus were highly conservative in many aspects, for example with identical stop codons and overlapping regions. But there were many differences in start codons, intergenic spacers, and numbers of mismatched base pairs of tRNA (transfer RNA genes).Our results, based on phylogenetic trees, genetic distances, species delimitation and genomic features (such as intergenic spacers) of the mitochondrial genome, indicated that D. tabulaeformis is as close to D. punctatus as is D. punctatus wenshanensis, whereas D. spectabilis evolved independently from D. tabulaeformis and D. punctatus. Whole mitochondrial DNA phylogenies showed that D. spectabilis formed a well-supported monophyletic clade, with a clear species boundary separating it from the other congeners examined here. However, D. tabulaeformis often clustered with D. punctatus and with the subspecies D. punctatus wenshanensis. Genetic distance analyses showed that the distance between D. tabulaeformis and D. punctatus is generally less than the intraspecific distance of D. punctatus and its subspecies D. punctatus wenshanensis. In the species delimitation analysis of Poisson Tree Processes (PTP), D. tabulaeformis, D. punctatus and D. punctatus wenshanensis clustered into a putative species separated from D. spectabilis. In comparison with D. spectabilis, D. tabulaeformis and D. punctatus also exhibit a similar structure in intergenic spacer characterization. These different types of evidence suggest that D. tabulaeformis is very close to D. punctatus and its subspecies D. punctatus wenshanensis, and is likely to be another subspecies of D. punctatus.

Conclusions

Whole mitochondrial genomes possess relatively rich genetic information compared with the traditional use of single or multiple genes for phylogenetic purposes. They can be used to better infer phylogenetic relationships and degrees of relatedness of taxonomic groups, at least from the aspect of maternal lineage: caution should be taken due to the maternal-only inheritance of this genome. Our results indicate that D. spectabilis is an independent lineage, while D. tabulaeformis shows an extremely close relationship to D. punctatus.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1566-5) contains supplementary material, which is available to authorized users.     

Molecular phylogeny of the Calyptratae (Diptera: Cyclorrhapha) with an emphasis on the superfamily Oestroidea and the position of Mystacinobiidae and McAlpine's fly

The dipteran clade Calyptratae is comprised of approximately 18 000 described species (12% of the known dipteran diversity) and includes well‐known taxa such as houseflies, tsetse flies, blowflies and botflies, which have a close association with humans. However, the phylogenetic relationships within this insect radiation are very poorly understood and controversial. Here we propose a higher‐level phylogenetic hypothesis for the Calyptratae based on an extensive DNA sequence dataset for 11 noncalyptrate outgroups and 247 calyptrate species representing all commonly accepted families in the Oestroidea and Hippoboscoidea, as well as those of the muscoid grade. DNA sequences for genes in the mitochondrial (12S, 16S, cytochrome c oxidase subunit I and cytochrome b) and nuclear genome [18S, 28S, the carbamoyl phosphate synthetase region of CAD (rudimentary), Elongation factor one alpha] were used to reconstruct the relationships. We discuss problems relating to the alignment and analysis of large datasets and emphasize the advantages of utilizing a guide tree‐based approach for the alignment of the DNA sequences and using the leaf stability index to identify ‘wildcard’ taxa whose excessive instability obscures the phylogenetic signal. Our analyses support the monophyly of the Calyptratae and demonstrate that the superfamily Oestroidea is nested within the muscoid grade. We confirm that the monotypic family Mystacinobiidae is an oestroid and further revise the composition of the Oestroidea by demonstrating that the previously unplaced and still undescribed ‘McAlpine’s fly’ is nested within this superfamily as a probable sister group to Mystacinobiidae. Within the Oestroidea we confirm with molecular data that the Calliphoridae are a paraphyletic grade of lineages. The families Sarcophagidae and Rhiniidae are monophyletic, but support for the monophyly of Tachinidae and Rhinophoridae depends on analytical technique (e.g. parsimony or maximum likelihood). The superfamilies Hippoboscoidea and Oestroidea are consistently found to be monophyletic, and the paraphyly of the muscoid grade is confirmed. In the overall relationships for the calyptrates, the Hippoboscoidea are sister group to the remaining Calyptratae, and the Fanniidae are sister group to the nonhippoboscoid calyptrates, whose relationships can be summarized as (Muscidae (Oestroidea (Scathophagidae, Anthomyiidae))).     

Phylogeny of the symphytan grade of Hymenoptera: new pieces into the old jigsaw(fly) puzzle

The Hymenoptera constitutes one of the largest, and ecologically and economically most important, insect orders. During the past decade, a number of hypotheses on the phylogenetic relationships among hymenopteran families and superfamilies have been presented, based on analyses of molecular and/or morphological data. Nevertheless, many questions still remain, particularly concerning relationships within the hyperdiverse suborder Apocrita, but also when it comes to the evolutionary history of the ancestrally herbivorous “sawfly” lineages that form the basal, paraphyletic grade Symphyta. Because a large part of the uncertainty appears to stem from limited molecular and taxonomic sampling, we set out to investigate the phylogeny of Hymenoptera using nine protein‐coding genes, of which five are new to analyses of the order. In addition, we more than tripled the taxon coverage across the symphytan grade, introducing representatives for many previously unsampled lineages. We recover a well supported phylogenetic structure for these early herbivorous hymenopteran clades, with new information regarding the monophyly of Xyelidae, the placement of the superfamily Pamphilioidea as sister to Tenthredinoidea + Unicalcarida, as well as the interrelationships among the tenthredinoid families Tenthredinidae, Cimbicidae, and Diprionidae. Based on the obtained phylogenies, and to prevent paraphyly of Tenthredinidae, we propose erection of the tribe Heptamelini to family status (Heptamelidae). In particular, our results give new insights into subfamilial relationships within the Tenthredinidae and other species‐rich sawfly families. The expanded gene set provides a useful toolbox for future detailed analyses of symphytan subgroups, especially within the diverse superfamily Tenthredinoidea.     

Plastid phylogenomics and molecular evolution of Alismatales

Past phylogenetic studies of the monocot order Alismatales left several higher‐order relationships unresolved. We addressed these uncertainties using a nearly complete genus‐level sampling of whole plastid genomes (gene sets representing 83 protein‐coding and ribosomal genes) from members of the core alismatid families, Tofieldiaceae and additional taxa (Araceae and other angiosperms). Parsimony and likelihood analyses inferred generally highly congruent phylogenetic relationships within the order, and several alternative likelihood partitioning schemes had little impact on patterns of clade support. All families with multiple genera were resolved as monophyletic, and we inferred strong bootstrap support for most inter‐ and intrafamilial relationships. The precise placement of Tofieldiaceae in the order was not well supported. Although most analyses inferred Tofieldiaceae to be the sister‐group of the rest of the order, one likelihood analysis indicated a contrasting Araceae‐sister arrangement. Acorus (Acorales) was not supported as a member of the order. We also investigated the molecular evolution of plastid NADH dehydrogenase, a large enzymatic complex that may play a role in photooxidative stress responses. Ancestral‐state reconstructions support four convergent losses of a functional NADH dehydrogenase complex in Alismatales, including a single loss in Tofieldiaceae.