Showing papers by "Rolf G. Beutel published in 2014"

Phylogenomics resolves the timing and pattern of insect evolution

Abstract: Insects are the most speciose group of animals, but the phylogenetic relationships of many major lineages remain unresolved. We inferred the phylogeny of insects from 1478 protein-coding genes. Phylogenomic analyses of nucleotide and amino acid sequences, with site-specific nucleotide or domain-specific amino acid substitution models, produced statistically robust and congruent results resolving previously controversial phylogenetic relations hips. We dated the origin of insects to the Early Ordovician [~479 million years ago (Ma)], of insect flight to the Early Devonian (~406 Ma), of major extant lineages to the Mississippian (~345 Ma), and the major diversification of holometabolous insects to the Early Cretaceous. Our phylogenomic study provides a comprehensive reliable scaffold for future comparative analyses of evolutionary innovations among insects.

The evolutionary history of holometabolous insects inferred from transcriptome-based phylogeny and comprehensive morphological data

Abstract: Despite considerable progress in systematics, a comprehensive scenario of the evolution of phenotypic characters in the mega-diverse Holometabola based on a solid phylogenetic hypothesis was still missing. We addressed this issue by de novo sequencing transcriptome libraries of representatives of all orders of holometabolan insects (13 species in total) and by using a previously published extensive morphological dataset. We tested competing phylogenetic hypotheses by analyzing various specifically designed sets of amino acid sequence data, using maximum likelihood (ML) based tree inference and Four-cluster Likelihood Mapping (FcLM). By maximum parsimony-based mapping of the morphological data on the phylogenetic relationships we traced evolutionary transformations at the phenotypic level and reconstructed the groundplan of Holometabola and of selected subgroups. In our analysis of the amino acid sequence data of 1,343 single-copy orthologous genes, Hymenoptera are placed as sister group to all remaining holometabolan orders, i.e., to a clade Aparaglossata, comprising two monophyletic subunits Mecopterida (Amphiesmenoptera + Antliophora) and Neuropteroidea (Neuropterida + Coleopterida). The monophyly of Coleopterida (Coleoptera and Strepsiptera) remains ambiguous in the analyses of the transcriptome data, but appears likely based on the morphological data. Highly supported relationships within Neuropterida and Antliophora are Raphidioptera + (Neuroptera + monophyletic Megaloptera), and Diptera + (Siphonaptera + Mecoptera). ML tree inference and FcLM yielded largely congruent results. However, FcLM, which was applied here for the first time to large phylogenomic supermatrices, displayed additional signal in the datasets that was not identified in the ML trees. Our phylogenetic results imply that an orthognathous larva belongs to the groundplan of Holometabola, with compound eyes and well-developed thoracic legs, externally feeding on plants or fungi. Ancestral larvae of Aparaglossata were prognathous, equipped with single larval eyes (stemmata), and possibly agile and predacious. Ancestral holometabolan adults likely resembled in their morphology the groundplan of adult neopteran insects. Within Aparaglossata, the adult’s flight apparatus and ovipositor underwent strong modifications. We show that the combination of well-resolved phylogenies obtained by phylogenomic analyses and well-documented extensive morphological datasets is an appropriate basis for reconstructing complex morphological transformations and for the inference of evolutionary histories.

Insect morphology in the age of phylogenomics: innovative techniques and its future role in systematics

Abstract: A brief account of the history of insect morphology is given. Different techniques and analytical methods used in current projects on insect morphology and phylogeny and their optimized combined application are described. These include fixation, dissection, maceration, histology (microtome sectioning), scanning electron microscopy (SEM), transmission electron microscopy (TEM), serial block-face scanning electron microscopy (SBFSEM), focused ion beam scanning electron microscopy (FIB/SEM), confocal laser scanning microscopy (CLSM), bleaching, micro-computed tomography (μCT), computer-based three-dimensional reconstruction, focus stacking of digital images, geometric morphometrics and the storage of morphological metadata. The role of insect morphology in the “age of phylogenomics” is discussed.

Phylogenomics Resolves The Timing And Pattern Of Insect Evolution: Supplementary File Archives.

Abstract: Toward an insect evolution resolution Insects are the most diverse group of animals, with the largest number of species. However, many of the evolutionary relationships between insect species have been controversial and difficult to resolve. Misof et al. performed a phylogenomic analysis of protein-coding genes from all major insect orders and close relatives, resolving the placement of taxa. The authors used this resolved phylogenetic tree together with fossil analysis to date the origin of insects to ~479 million years ago and to resolve long-controversial subjects in insect phylogeny. Science, this issue p. 763 The phylogeny of all major insect lineages reveals how and when insects diversified. Insects are the most speciose group of animals, but the phylogenetic relationships of many major lineages remain unresolved. We inferred the phylogeny of insects from 1478 protein-coding genes. Phylogenomic analyses of nucleotide and amino acid sequences, with site-specific nucleotide or domain-specific amino acid substitution models, produced statistically robust and congruent results resolving previously controversial phylogenetic relations hips. We dated the origin of insects to the Early Ordovician [~479 million years ago (Ma)], of insect flight to the Early Devonian (~406 Ma), of major extant lineages to the Mississippian (~345 Ma), and the major diversification of holometabolous insects to the Early Cretaceous. Our phylogenomic study provides a comprehensive reliable scaffold for future comparative analyses of evolutionary innovations among insects.

Morphology and Systematics (phytophaga)

Abstract: This book is the third volume in the Handbook of Zoology series which treats the systematics and biology of Coleoptera. With approximately 350,000 described species, Coleoptera are by far the most species - rich order of insects and the largest group of animals of comparable geological age. This third Coleoptera volume completes the Morphology and Systematics volumes with 43 chapters and covers one of the largest radiations of beetles, the mainly plant-feeding Phytophaga, with information on world distribution, biology, morphology and anatomy, phylogeny and comments on taxonomy.

100 years Zoraptera : a phantom in insect evolution and the history of its investigation

Abstract: Zoraptera are a cryptic and enigmatic group of insects. The species diversity is lower than in almost all other groups of Hexapoda, but may be distinctly higher than presently known. Several new species were described from different regions recently. The systematic placement was discussed controversially since the group was discovered 100 years ago. Affinities with Isoptera and Psocoptera were discussed in earlier studies. A sister group relationship with Acercaria (Psocodea, Thysanoptera, Hemiptera) was proposed by W. Hennig, for the first time based on a strictly phylogenetic argumentation. More recent studies consistently suggest a placement among the “lower neopteran orders” (Polyneoptera). Close affinities to Dictyoptera were proposed and alternatively a sister group relationship with Embioptera or with Embioptera + Phasmatodea (Eukinolabia), respectively. The precise placement is still controversial and the intraordinal relationships are largely unclear. Recent transcriptome analyses tentatively suggest a clade Zoraptera + Dermaptera as sister group of all other polyneopteran orders. The oldest fossils are from Cretaceous amber. An extinct genus from this era may be the sister group of all the remaining zorapterans. The knowledge of the morphology, development and features related to the reproductive system greatly increased in recent years. The general body morphology is very uniform, whereas the genitalia differ strongly between species. This is likely due to different kinds of selection, i.e. sexual selection in the case of the genital organs. The mating pattern also differs profoundly within the order. A unique external sperm transfer occurs in Zorotypus impolitus. A species-level phylogeny and more investigations of the reproductive system should have high priority.

Embryonic development of Zoraptera with special reference to external morphology, and its phylogenetic implications (Insecta)

Abstract: The embryonic development of Zorotypus caudelli Karny (Zoraptera) is described with the main focus on its external features. A small heart-shaped embryo is formed on the dorsal side of the egg by the fusion of paired blastoderm regions with higher cellular density. The orientation of its anteroposterior axis is opposed to that of the egg. This unusual condition shows the potential autapomorphy of Zoraptera. The embryo extends along the egg surface and after reach- ing its full length, it migrates into the yolk. After developing there for a period of time, it reappears on the surface, accompanied by a reversion of its antero- posterior axis, finally taking its position on the ventral side of the egg. The definitive dorsal closure completes, and the prelarva hatches after perforating the chorion with very long egg tooth formed on the embryonic cuti- cle. Embryological data suggest the placement of Zor- aptera among the "lower neopteran" or polyneopteran lineage: features supporting this are embryo formation by the fusion of paired regions with higher cellular density and blastokinesis accompanied by full elonga- tion of the embryo on the egg surface. The extraordi- narily long egg tooth has potential synapomorphy with Embioptera or Eukinolabia (5 Embioptera 1 Phasma- todea). Together with the results from our previous studies on the egg structure, male reproductive system and spermatozoa, the close affinity of Zoraptera with Eukinolabia appears likely, that is, a clade Zoraptera 1 (Embioptera 1 Phasmatodea). J. Morphol. 000:000-

Two intromittent organs inZorotypus caudelli(Insecta, Zoraptera): the paradoxical coexistence of an extremely long tube and a large spermatophore

Abstract: Very unusual genitalia of the species Zorotypus caudelli are described. It contains the unique configuration of two different intromittent organs, one of them strongly elongated. Hyper elongated genitalia are known in different groups of insects. Males have to accommodate these unwieldy structures in the limited spaces of the abdomen and manipulate them acutely during copulation. A crucial question is how do species with elongated genitalia cope with these requirements? To investigate this, we studied key features enabling storage, insertion, and withdrawal of the elongated genitalia. The co-existence of an elongated narrow tube and a bulky spermatophore is a highly unusual and apparently paradoxical condition. However, we demonstrate that the tube is not involved in sperm transmission, whereas the large spermatophore is transferred to females by a membranous fold of the genitalia. The movement of the spermatophore is caused by haemolymph pressure, which likely also promotes the insertion of both intromittent organs. A comparison with the genital anatomy and reproductive mode in related groups suggests that the elongated tube and its accommodating pouch is a de novo structure, and that the ancestral sperm transport via spermatophore is a preadaptive condition for the acquisition of this unusual structure

Ice Crawlers (Grylloblattodea) – the history of the investigation of a highly unusual group of insects

Abstract: Grylloblattodea are one of the most unusual groups of insects and the second smallest order. All known extant species are wingless and exhibit a remarkable preference for cold temperatures. Although their morphology was intensively investigated shortly after their discovery, the systematic position has been disputed for a long time. The placement of Grylloblattodea as sister-group to the recently described Mantophasamtodea is supported by morphological and molecular evidence. However, the relationships of this clade, Xenonomia, among the polyneopteran lineages is not clear. Transcriptome analyses, in addition to the study of winged grylloblattodean fossils, may help to clarify the position of Xenonomia and aid in the reconstruction of the “phylogenetic backbone” of Polyneoptera.

Fly on the wall – attachment structures in lower Diptera

Abstract: Pretarsal attachment structures of representatives of the megadiverse Diptera are examined and documented, mainly using scanning electron microscopy. The focus is on the basal 'nematoceran' lineages. The diversity in structures is much higher than suggested by brief summarizing accounts in earlier studies. Both hairy and smooth attachment structures occur. A well-developed, pad-like empodium with its ventral surface covered with adhesive hairs is arguably a groundplan feature of Diptera. Very often this pad is combined with the presence of hairy pulvilli. However, smooth pulvilli occur in two of the examined groups. A smooth arolium is present in Tipulomorpha and likely an autapomorphy of this clade, suggesting that it was acquired secondarily. Evolutionary transformations are interpreted based on recently published dipteran phylogenies.

Molecular phylogeny of the leaf beetle subfamily Criocerinae (Insecta: Coleoptera: Chrysomelidae) and the correlated evolution of reproductive organs.

Abstract: Phylogenetic relationships among major groups of Criocerinae were reconstructed using molecular data (mitochondrial cytochrome oxidase I and 12S rDNA, and nuclear histone 3). The monophyly of Criocerinae was consistently and robustly supported. The Lema group including Lema, Oulema and Neolema was recovered as a clade, with the latter two genera imbedded within Lema. The Lilioceris group was placed as the sister taxon of the Lema group, and the genus Crioceris was identified as the sister taxon of the Lilioceris + Lema groups. The monophyly and/or validity of Mecoprosopus Chujo, 1951 and the subgenera Lema, Petauristes Latreille, 1829, Quasilema Monros, 1960, Microlema Pic, 1932, and Bradyceris Chujo, 1951 were not confirmed. The monophyly of the subgenus Lema except for the type species L. cyanea was supported by molecular and morphological data, and we termed it the cyanella clade. The present molecular phylogeny was compared with previous concepts with respect to the validity of each genus/subgenus. A revision of several genera is necessary. Based on the phylogenic result, the character evolution of the reproductive organs was analyzed. The ancestral states of this character system were parsimoniously reconstructed. Various shapes of the spermatheca were observed in the subfamily. A convoluted spermatheca evolved once, and reversals to the ancestral state took place several times independently. An elongation of a part of the intromittent organ also occurred several times independently. The length of the male and female reproductive ducts, which are in physical contact during copulation, showed a tight positive correlation even after removing phylogenetic effects. This strongly suggests coevolution between the male and female genital length.

Description of a new species of Glaresidae (Coleoptera: Scarabaeoidea) from the Jehol Biota of China with a geometric morphometric evaluation

Abstract: Glaresis tridentata Bai, Beutel & Ren sp. nov. (Scarabaeoidea: Glaresidae) from the Yixian Formation of western Liaoning Province, NE China is described and illustrated. A geometric morphometric analysis of three character systems (head, metatibia and aedeagus) was carried out including 136 specimens from 44 species of three genera of extant and extinct Glaresidae. The variation in these features between Glaresis tridentata Bai, Beutel & Ren sp. nov. and the other species was estimated based on Principal Component Analysis (PCA), Canonical Variate Analysis (CVA), Discriminant function analysis (DFA) and Minimum Spanning Tree (MST) approaches. The results suggest that Glaresidae, likely the sister group of all other extant Scarabaeoidea, had been established in the Early Cretaceous and contained larger species than today. The assignement of the new species to the genus Glaresis is supported. The validity of the genera Lithoglaresis and Cretoglaresis is questionable.

Postembryonic development of the ground louse Zorotypus caudelli Karny (Insecta: Zoraptera: Zorotypidae)

Abstract: Based on captive breeding, the postembryonic development of the ground louse Zorotypus caudelli Karny, 1927 (Zoraptera, Zorotypidae) was examined and described in detail. The number of nymphal instars in Z. caudelli is five. During the second molt (2nd to 3rd instar), the number of antennomeres increases from eight to nine by subdivision of the basal flagellomere (meriston). Apterous and winged forms differentiate in the 4th nymphal instar. In the 4th instar of the winged form, small wing pads and small ocular spots appear. In the 5th instar, the wing pads elongate and the ocular spots are widened, and three ocelli are differentiated. Wing dimorphism may be a phenomenon independent of crowding. The two sexes closely resemble each other as in other zorapteran species, and sexual dimorphism does not appear until the final (5th) nymphal instar: in the 5th instar of males, setae increase in number on the 9th and 10 + 11th abdominal terga, and a small posteromedian swelling appears on the 10 + 11th abdominal tergum, the precursor of the mating hook. Key to nymphal instars of Zorotypus caudelli was given. The formation of thoracic pleural sclerites was examined and revaluated.