Interrelationships of Staphyliniform groups inferred from 18S and 28S rDNA sequences, with special emphasis on Hydrophiloidea (Coleoptera, Staphyliniformia)

Large carrion and burying beetles evolved from Staphylinidae (Coleoptera, Staphylinidae, Silphinae): a review of the evidence

Large carrion beetles (Silphidae) are the focus of ongoing behavioral ecology, forensic, ecological, conservation, evolutionary, systematic, and other research, and were recently reclassified as a subfamily of Staphylinidae. Twenty-three analyses in 21 publications spanning the years 1927-2023 that are relevant to the question of the evolutionary origin and taxonomic classification of Silphidae are reviewed. Most of these analyses (20) found Silphidae nested inside Staphylinidae (an average of 4.38 branches deep), two found Silphidae in an ambiguous position, and one found Silphidae outside Staphylinidae, as sister to Hydrophilidae. There is strong evidence supporting the hypothesis that large carrion beetles evolved from within Staphylinidae and good justification for their classification as the subfamily Silphinae of the megadiverse, and apparently now monophyletic, Staphylinidae. Considerable uncertainty remains regarding the interrelationships and monophyly of many staphylinid subfamilies. Nonetheless, the subfamily Tachyporinae was found to be the sister of Silphinae in more analyses (7) than any other subfamily.

Phylogeny and evolution of Mesozoic and extant lineages of Histeridae (Coleoptera), with discovery of a new subfamily Antigracilinae from the Lower Cretaceous

In order to place a newly discovered species Antigracilus costatus gen. sp. n. from the Lower Cretaceous Yixian Formation (China) and to assess previously unplaced fossil taxa, we investigated the relationships of extant and extinct lineages of Histeridae based on three data sets: (i) 69 morphological characters belonging to 48 taxa (representing all 11 subfamilies and 15 of 17 tribes of modern Histeridae); (ii) partitioned alignment of 6030 bp from downloaded nucleotide sequences (28S, CAD, COI, 18S) of 50 taxa (representing 10 subfamilies and 15 of 17 tribes of modern Histeridae); and (iii) a combined morphological and molecular dataset for 75 taxa. Phylogenetic analyses of the morphology and combined matrices recovered the new Lower Cretaceous taxon as a sister group to remaining Histeridae and it is placed in †Antigracilinae subfam. n. †Antigracilinae constitutes the earliest record of Histeridae from the Lower Cretaceous Yixian Formation (∼125 Myr), backdating the minimum age of the family by 25 Myr from the earliest Cenomanian (~99 Myr) to the Barremian of the Cretaceous Period. Our molecular phylogeny supports Histeridae to be divided into seven different clades, with currently recognised subfamilies Abraeinae (sensu lato), Saprininae, Chlamydopsinae, and Histerinae (sensu lato) recovered as monophyletic, while Dendrophilinae, Onthophilinae, and Tribalinae are polyphyletic taxa. The Burmese amber species †Pantostictus burmanicus Poinar & Brown is placed as a sister group to the tribe Plegaderini (Abraeinae) and was assigned as a new tribe Pantostictini trib. n. Both molecular and combined phylogenies recovered the subfamilies Trypanaeinae and Trypeticinae deeply within the subfamily Abraeinae (sensu lato), and they are downgraded into Trypanaeini stat. n. and Trypeticini stat. n.

Telomeric DNA sequences in beetle taxa vary with species richness

Telomeres are protective structures at the ends of eukaryotic chromosomes, and disruption of their nucleoprotein composition usually results in genome instability and cell death. Telomeric DNA sequences have generally been found to be exceptionally conserved in evolution, and the most common pattern of telomeric sequences across eukaryotes is (TxAyGz)n maintained by telomerase. However, telomerase-added DNA repeats in some insect taxa frequently vary, show unusual features, and can even be absent. It has been speculated about factors that might allow frequent changes in telomere composition in Insecta. Coleoptera (beetles) is the largest of all insect orders and based on previously available data, it seemed that the telomeric sequence of beetles varies to a great extent. We performed an extensive mapping of the (TTAGG)n sequence, the ancestral telomeric sequence in Insects, across the main branches of Coleoptera. Our study indicates that the (TTAGG)n sequence has been repeatedly or completely lost in more than half of the tested beetle superfamilies. Although the exact telomeric motif in most of the (TTAGG)n-negative beetles is unknown, we found that the (TTAGG)n sequence has been replaced by two alternative telomeric motifs, the (TCAGG)n and (TTAGGG)n, in at least three superfamilies of Coleoptera. The diversity of the telomeric motifs was positively related to the species richness of taxa, regardless of the age of the taxa. The presence/absence of the (TTAGG)n sequence highly varied within the Curculionoidea, Chrysomeloidea, and Staphylinoidea, which are the three most diverse superfamilies within Metazoa. Our data supports the hypothesis that telomere dysfunctions can initiate rapid genomic changes that lead to reproductive isolation and speciation.

Higher-level phylogenetic relationships of rove beetles (Coleoptera, Staphylinidae) inferred from mitochondrial genome sequences

Rove beetles (Staphylinidae) and allied families constitute a huge radiation of Coleoptera, but basal relationships in this group remain controversial. In this study, we newly sequenced eight mitogenomes of representatives of Staphylinidae by using next-generation sequencing method. Together with 99 existing mitogenomes of Staphyliniformia, (sub)family relationships were investigated with ML and Bayesian searches under various substitution models and data recoding schemes. The results consistently supported Scydmaenidae and Silphidae to be subordinate groups of Staphylinidae. Within the monophyletic Staphylinidae (including Scydmaenidae and Silphidae), the hypothesis of four major subfamily groups cannot be confirmed. Bayesian inferences under the site-heterogeneous mixture model generally supported the basal position of major clades corresponding to the Omaliine group. At the subfamily level, the monophyly of Pselaphinae, Oxytelinae, Scaphidiinae, Steninae and Staphylininae was supported. However, the subfamilies Omaliinae, Tachyporinae, Aleocharinae and Paederinae were each non-monophyletic.

Wolbachia distribution in selected beetle taxa characterized by PCR screens and MLST data

Wolbachia (Alphaproteobacteria) is an inherited endosymbiont of arthropods and filarial nematodes and was reported to be widespread across insect taxa. While Wolbachia's effects on host biology are not understood from most of these hosts, known Wolbachia‐induced phenotypes cover a spectrum from obligate beneficial mutualism to reproductive manipulations and pathogenicity. Interestingly, data on Wolbachia within the most species‐rich order of arthropods, the Coleoptera (beetles), are scarce. Therefore, we screened 128 species from seven beetle families (Buprestidae, Hydraenidae, Dytiscidae, Hydrophilidae, Gyrinidae, Haliplidae, and Noteridae) for the presence of Wolbachia. Our data show that, contrary to previous estimations, Wolbachia frequencies in beetles (31% overall) are comparable to the ones in other insects. In addition, we used Wolbachia MLST data and host phylogeny to explore the evolutionary history of Wolbachia strains from Hydraenidae, an aquatic lineage of beetles. Our data suggest that Wolbachia from Hydraenidae might be largely host genus specific and that Wolbachia strain phylogeny is not independent to that of its hosts. As this contrasts with most terrestrial Wolbachia–arthropod systems, one potential conclusion is that aquatic lifestyle of hosts may result in Wolbachia distribution patterns distinct from those of terrestrial hosts. Our data thus provide both insights into Wolbachia distribution among beetles in general and a first glimpse of Wolbachia distribution patterns among aquatic host lineages.

The larval head structures of Podagricomela shirahatai (Chûjô) (Chrysomelidae, Galerucinae, Alticini) and morphological effects of leaf mining

Head structures of the leaf mining larva of the chrysomelid species Podagricomela shirahatai are described and illustrated. Internal and external structures were reconstructed three dimensionally based on image stacks obtained with microcomputed tomography. The larval head is characterized by prognathism, a dorsoventrally compressed shape, a flattened maxillolabial complex, a completely reduced coronal suture, and the presence of a deep, V-shaped posterior emargination of the head capsule. Internal structures are not distinctly affected by leaf mining. The cephalic features are compared with conditions found in surface feeding and root feeding alticine larvae and also with characters of chrysomeline larvae of Chrysomela populi Linnaeus. Possible correlations between modifications of the larval head and different feeding behaviors are discussed. Characters are also discussed with respect to possible phylogenetic implications. Some derived features are apparently due to phylogenetic constraints. Apomorphies characterizing alticine larvae with distinctly different life habits are the loss of M. frontoepharyngalis (M. 9), the origin of M. tentoriostipitalis (M. 18) from the head capsule, two insertions of M. tentoriopraementalis inferior (M. 29) and the reduction of stemmata. The study underlines that the anatomical study of chrysomeloid larvae is not only highly desirable in a phylogenetic context, but also crucial for understanding the evolution of different life strategies in this extremely successful group of Coleoptera.

How old are the rove beetles (Insecta: Coleoptera: Staphylinidae) and their lineages? Seeking an answer with DNA

The phylogeny and related evolutionary history of rove beetles (Coleoptera, Staphylinidae) remain unclear. This study provides phylogenetic analyses for the family based on three genes (mitochondrial COI, nuclear protein-coding wingless and a portion of the ribosomal 28S rDNA) including 2413 bp for 104 taxa representing most major staphylinid lineages. The subfamilies Oxyporinae, Paederinae, Steninae, and Proteininae are all well-supported clades, as evidenced by all three inference methods, namely maximum parsimony, Bayesian inference, and maximum likelihood. From fossils available for calibration, the divergence time of the main lineages in the family is estimated based on an uncorrelated lognormal relaxed molecular clock analysis method. The molecular clock analysis suggests that the family Staphylinidae dates from approximately the Early Triassic epoch and the most lineages of the family started to radiate from the Late Jurassic to the Early Paleogene.

Noisy: identification of problematic columns in multiple sequence alignments

MOTIVATION

Sequence-based methods for phylogenetic reconstruction from (nucleic acid) sequence data are notoriously plagued by two effects: homoplasies and alignment errors. Large evolutionary distances imply a large number of homoplastic sites. As most protein-coding genes show dramatic variations in substitution rates that are not uncorrelated across the sequence, this often leads to a patchwork pattern of (i) phylogenetically informative and (ii) effectively randomized regions. In highly variable regions, furthermore, alignment errors accumulate resulting in sometimes misleading signals in phylogenetic reconstruction.

RESULTS

We present here a method that, based on assessing the distribution of character states along a cyclic ordering of the taxa, allows the identification of phylogenetically uninformative homoplastic sites in a multiple sequence alignment. Removal of these sites appears to improve the performance of phylogenetic reconstruction algorithms as measured by various indices of "tree quality". In particular, we obtain more stable trees due to the exclusion of phylogenetically incompatible sites that most likely represent strongly randomized characters.

SOFTWARE

The computer program noisy implements this approach. It can be employed to improving phylogenetic reconstruction capability with quite a considerable success rate whenever (1) the average bootstrap support obtained from the original alignment is low, and (2) there are sufficiently many taxa in the data set - at least, say, 12 to 15 taxa. The software can be obtained under the GNU Public License from http://www.bioinf.uni-leipzig.de/Software/noisy/.

Molecular phylogeny of the Heterotrichea (Ciliophora, Postciliodesmatophora) based on small subunit rRNA gene sequences

A comprehensive molecular analysis of the phylogenetic relationships within the Heterotrichea including all described families is still lacking. For this reason, the complete nuclear small subunit (SSU) rDNA was sequenced from further representatives of the Blepharismidae and the Stentoridae. In addition, the SSU rDNA of a new, undescribed species of the genus Condylostomides (Condylostomatidae) was sequenced. The detailed phylogenetic analyses revealed a consistent branching pattern: while the terminal branches are generally well resolved, the basal relationships remain unsolved. Moreover, the data allow some conclusions about the macronuclear evolution within the genera Blepharisma, Stentor, and Spirostomum suggesting that a single, compact macronucleus represents the ancestral state.

The evolutionary process of bioluminescence and aposematism in cantharoid beetles (Coleoptera: Elateroidea) inferred by the analysis of 18S ribosomal DNA

Cantharoid beetles are distinctive for their leathery soft elytra and conspicuous color or bioluminescence, and many of the members are equipped with chemical defenses. Thus, the vivid coloration of Cantharidae and Lycidae and the bioluminescence in Lampyridae and Phengodidae appear to be aposematic signals. However, the evolutionary aspect of their aposematism is not well understood, because the classification of the families remains controversial. In this study, we performed molecular phylogenetic analyses of species from cantharoid families, based on nucleotide sequence comparisons of nuclear 18S ribosomal DNA. The results shows that the luminous species Rhagophthalmus ohbai, which had sometimes been classified in Lampyridae, is excluded from a lampyrid clade and associates with the taxa of Phengodidae. The molecular data also suggests that four major subfamilies of Cantharidae (Cantharinae, Chauliognathinae, Malthininae, and Silinae) form a clade. The six subfamilies of Lampyridae are grouped and classified into two sublineages: Amydetinae+Lampyrinae+Photurinae and Cyphonocerinae+Luciolinae+Ototretinae. Genera Drilaster and Stenocladius are the members of Ototretinae in Lampyridae. These results conform to traditional taxonomy but disagree with more recent cladistic analyses. Based on these findings, we propose an evolutionary process of bioluminescence and aposematism in cantharoids: the clades of Cantharidae, Lampyridae, Lycidae, and Phengodidae have evolved aposematic coloration; subsequently Lampyridae and Phengodidae acquired bioluminescence; and these four major cantharoid families achieved their current adaptive diversities.

Dense taxonomic EST sampling and its applications for molecular systematics of the Coleoptera (beetles)

Expressed sequence tag (EST) sequences can provide a wealth of data for phylogenetic and genomic studies, but the utility of these resources is restricted by poor taxonomic sampling. Here, we use small EST libraries (<1,000 clones) to generate phylogenetic markers across a broad sample of insects, focusing on the species-rich Coleoptera (beetles). We sequenced over 23,000 ESTs from 34 taxa, which produced 8,728 unique sequences after clustering nonredundant sequences. Between taxa, the sequences could be grouped into 731 gene clusters, with the largest corresponding to mitochondrial DNA transcripts and gene families chymotrypsin, actin, troponin, and tubulin. While levels of paralogy were high in most gene clusters, several midsized clusters including many ribosomal protein (RP) genes appeared to be free of expressed paralogs. To evaluate the utility of EST data for molecular systematics, we curated available transcripts for 66 RP genes from representatives of the major groups of Coleoptera. Using supertree and supermatrix approaches for phylogenetic analysis, the results were consistent with the emerging phylogenetic conclusions about basal relationships in Coleoptera. Numerous small EST libraries from a taxonomically densely sampled lineage can provide a core set of genes that together act as a scaffold in phylogenetic reconstruction, comparative genomics, and studies of gene evolution.