Our love-hate relationship with DNA barcodes, the Y2K problem, and the search for next generation barcodes

Comparative Mitogenomic Analyses of Hydropsychidae Revealing the Novel Rearrangement of Protein-Coding Gene and tRNA (Trichoptera: Annulipalpia)

Gene rearrangement of the mitochondrial genome of insects, especially the rearrangement of protein-coding genes, has long been a hot topic for entomologists. Although mitochondrial gene rearrangement is common within Annulipalpia, protein-coding gene rearrangement is relatively rare. As the largest family in Annulipalpia, the available mitogenomes from Hydropsychidae Curtis, 1835 are scarce, and thus restrict our interpretation of the mitogenome characteristic. In this study, we obtained 19 novel mitogenomes of Hydropsychidae, of which the mitogenomes of the genus Arctopsyche are published for the first time. Coupled with published hydropsychid mitogenome, we analyzed the nucleotide composition evolutionary rates and gene rearrangements of the mitogenomes among subfamilies. As a result, we found two novel gene rearrangement patterns within Hydropsychidae, including rearrangement of protein-coding genes. Meanwhile, our results consider that the protein-coding gene arrangement of Potamyia can be interpreted by the tandem duplication/random loss (TDRL) model. In addition, the phylogenetic relationships within Hydropsychidae constructed by two strategies (Bayesian inference and maximum likelihood) strongly support the monophyly of Arctopscychinae, Diplectroninae, Hydropsychinae, and Macronematinae. Our study provides new insights into the mechanisms and patterns of mitogenome rearrangements in Hydropsychidae.

A global molecular phylogeny yields insights into the dispersal and invasion history of Junonia, a butterfly genus with remarkable dispersal abilities

The nymphalid butterfly genus Junonia has remarkable dispersal abilities. Occurring on every continent except Europe and Antarctica, Junonia are often among the only butterflies on remote oceanic islands. The biogeography of Junonia has been controversial, plagued by taxonomic disputes, small phylogenetic datasets, incomplete taxon sampling, and shared interspecific mitochondrial haplotypes. Junonia originated in Africa but its route into the New World remains unknown. Presented here is, to our knowledge, the most comprehensive Junonia phylogeny to date, using full mitogenomes and nuclear ribosomal RNA repeats from 40 of 47 described species. Junonia is monophyletic and the genus Salamis is its probable sister clade. Genetic exchange between Indo-Pacific Junonia villida and New World Junonia vestina is evident, suggesting a trans-Pacific route into the New World. However, in both phylogenies, the sister clades to most New World Junonia contain both African and Asian species. Multiple trans-Atlantic or trans-Pacificinvasions could have contributed to New World diversification. Hybridization and lateral transfer of mitogenomes, already well-documented in New World Junonia, also occurs in at least two Old World lineages (Junonia orithya/Junonia hierta and Junonia iphita/Junonia hedonia). Variation associated with reticulate evolution creates challenges for phylogenetic reconstruction, but also may have contributed to patterns of speciation and diversification in this genus.

The complete mitochondrial genome of the smudged eighty-eight butterfly Diaethria gabaza eupepla (Salvin & Godman, 1868) (Insecta: Lepidoptera: Nymphalidae)

The smudged eighty-eight butterfly Diaethria gabaza eupepla (Salvin & Godman, 1868) (Nymphalidae) is a vividly colored aposematic butterfly from Central and South America. A complete circular mitochondrial genome (mitogenome) of 15,156 bp from D. gabaza eupepla was assembled from a genome skimming Illumina sequence library. The AT-rich (80.5% AT) mitogenome consists of 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a control region in the typical butterfly gene order. Diaethria gabaza eupepla COX1 begins with an atypical CGA start codon and ATP6, COX1, COX2, CYTB, ND1, ND4, ND4L, and ND5 mRNAs contain incomplete stop codons completed by the addition of 3' A residues. Phylogenetic reconstruction places Diaethria as the sister clade to Hamadryas within monophyletic nymphalid subfamily Biblidinae, consistent with previous phylogenetic hypotheses.

Lack of Statistical Rigor in DNA Barcoding Likely Invalidates the Presence of a True Species' Barcode Gap

DNA barcoding has been largely successful in satisfactorily exposing levels of standing genetic diversity for a wide range of taxonomic groups through the employment of only one or a few universal gene markers. However, sufficient coverage of geographically-broad intra-specific haplotype variation within genomic databases like the Barcode of Life Data Systems (BOLD) and GenBank remains relatively sparse. As reference sequence libraries continue to grow exponentially in size, there is now the need to identify novel ways of meaningfully analyzing vast amounts of available DNA barcode data. This is an important issue to address promptly for the routine tasks of specimen identification and species discovery, which have seen broad adoption in areas as diverse as regulatory forensics and resource conservation. Here, it is demonstrated that the interpretation of DNA barcoding data is lacking in statistical rigor. To highlight this, focus is set specifically on one key concept that has become a household name in the field: the DNA barcode gap. Arguments outlined herein specifically center on DNA barcoding in animal taxa and stem from three angles: (1) the improper allocation of specimen sampling effort necessary to capture adequate levels of within-species genetic variation, (2) failing to properly visualize intra-specific and interspecific genetic distances, and (3) the inconsistent, inappropriate use, or absence of statistical inferential procedures in DNA barcoding gap analyses. Furthermore, simple statistical solutions are outlined which can greatly propel the use of DNA barcoding as a tool to irrefutably match unknowns to knowns on the basis of the barcoding gap with a high degree of confidence. Proposed methods examined herein are illustrated through application to DNA barcode sequence data from Canadian Pacific fish species as a case study.

The complete mitochondrial genome of the pirate butterfly Catacroptera cloanthe (Stoll, 1781) (Insecta: Lepidoptera: Nymphalidae: Kallimini)

The pirate butterfly Catacroptera cloanthe (Stoll, 1781) (Nymphalidae: Kallimini) is a monotypic genus of butterfly that occupies grassland and savanna habitats in Sub-Saharan Africa, and exhibits seasonal variation. Genome skimming by Illumina sequencing allowed the assembly of a 78.8% AT-rich complete circular mitogenome of 15,204 bp from C. cloanthe. The mitogenome has a typical butterfly gene order consisting of 13 protein-coding genes, two rRNAs, 22 tRNAs, and a control region. Catacroptera cloanthe COX1 begins with an atypical CGA start codon, while COX2, ND3, ND4, and ND5 end with incomplete T or TA stop codons, completed by the addition of the poly-A tail during mRNA processing. Bayesian phylogenetic reconstruction placed Catacroptera cloanthe as sister to Mallika jacksoni in the monophyletic tribe Kallimini, which was consistent with previous phylogenetic hypotheses.

Phylogenetic analysis of the complete mitochondrial genome of the Blomfild's Beauty butterfly Smyrna blomfildia (Fabricius 1781) (Insecta: Lepidoptera: Nymphalidae: Nymphalini)

The Blomfild's Beauty butterfly Smyrna blomfildia (Fabricius 1781) (Lepidoptera: Nymphalidae: Nymphalini) is a sexually dimorphic species found in Mexico, Central, and South America. Males are territorial and are more vibrantly colored than females. Genome skimming by Illumina sequencing allowed the assembly of a complete circular mitochondrial genome (mitogenome) of 15,149 bp from S. blomfildia consisting of 83.9% AT nucleotides, 13 protein-coding genes, 22 tRNAs, two rRNAs, and a control region in the typical butterfly gene order. The S. blomfilda COX1 gene features an atypical start codon (CGA) while ATP6, COX1, COX2, CYTB, ND1, ND3, ND4, and ND5 display partial stop codons completed by the addition of 3' A residues to the mRNA. Bayesian phylogenetic reconstruction places Smyrna as a member of the tribe Nymphalini and sister to a clade containing genera Araschnia, Vanessa, Polygonia, and Aglais, which differs from its classic taxonomic placement in tribe Coeini.

The complete mitochondrial genome of the file ramshorn snail Planorbella pilsbryi (Mollusca: Gastropoda: Hygrophila: Planorbidae)

The file ramshorn snail Planorbella pilsbryi Baker, 1926 (Gastropoda: Hygrophila: Planorbidae) is a widespread herbivorous North American freshwater snail found in diverse habitats, including standing and moving water bodies. Genome skimming by Illumina sequencing allowed the assembly of a complete nuclear rRNA repeat sequence and a complete circular mitogenome of 13,720 bp from P. pilsbryi consisting of 75.3% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the typical order found in panpulmonate snails. Planorbella pilsbryi COXI features a rare TTG start codon while COXII, CYTB, ND2, ND3, and ND5 exhibit incomplete stop codons completed by the addition of 3' A residues to the mRNA. Phylogenetic reconstruction of mitochondrial protein-coding gene and rRNA sequences places P. pilsbryi as sister taxon to Planorbella duryi (Planorbidae) within family Planorbidae, which is consistent with previous phylogenetic hypotheses.

Phylogenetic analysis of the complete mitochondrial genome of the Japanese peacock butterfly Aglais io geisha (Stichel 1907) (Insecta: Lepidoptera: Nymphalidae)

The peacock butterfly Aglais io (Linnaeus, 1758) (Nymphalidae: Nymphalinae: Nymphalini) is a colorful and charismatic flagship butterfly species whose range spans from the British Isles and Europe through temperate Asia and the Far East. In Europe, it has been used as a model species for studying the effects of GMO maize pollen on caterpillar growth and survivorship. The Japanese subspecies, Aglais io geisha (Stichel 1907), is not as well studied as its European counterpart. Genome skimming by Illumina sequencing allowed the assembly of a complete circular mitochondrial genome (mitogenome) of 15,252 bp from A. io geisha consisting of 80.6% AT nucleotides, 13 protein-coding genes, 22 tRNAs, two rRNAs, and a control region in the gene order typical of butterfly species. Aglais io geisha COX1 gene features an atypical start codon (CGA) while COX1, COX2, CYTB, ND1, ND3, ND4, and ND5 display incomplete stop codons finished by the addition of 3' A residues to the mRNA. Bayesian phylogenetic reconstruction places A. io geisha within a clade with European A. io mitogenomes in the tribe Nymphalini, which is consistent with previous phylogenetic hypotheses.

The complete mitochondrial genome of the Indian leafwing butterfly Kallima paralekta (insecta: Lepidoptera: Nymphalidae)

The Indian leafwing butterfly Kallima paralekta (Horsfield, 1829) (Nymphalidae) is an Asian forest-dwelling, leaf-mimic. Genome skimming by Illumina sequencing permitted assembly of a complete circular mitogenome of 15,200 bp from K. paralekta consisting of 79.5% AT nucleotides, 22 tRNAs, 13 protein-coding genes, two rRNAs and a control region in the typical butterfly gene order. Kallima paralekta COX1 features an atypical CGA start codon, while ATP6, COX1, COX2, ND4, ND4L, and ND5 exhibit incomplete stop codons completed by 3' A residues added to the mRNA. Phylogenetic reconstruction places K. paraleckta within the monophyletic genus Kallima, sister to Mallika in the subfamily Nymphalinae. These data support the monophyly of tribe Kallimini and contribute to the evolutionary systematics of the Nymphalidae.

Phylogenetic analysis of the complete mitochondrial genome of the white peacock butterfly Anartia jatrophae saturata (Insecta: Lepidoptera: Nymphalidae)

The white peacock butterfly Anartia jatrophae saturata Staudinger, 1884 (Nymphalidae: Nymphalinae: Victorini), lives in the neotropics. Genome skimming with Illumina sequencing of A. jatrophae saturata allowed the assembly of a complete circular mitogenome of 15,297 bp, consisting of 81.4% AT nucleotides, 22 tRNAs, 13 protein-coding genes, two rRNAs, and a control region. Anartia jatrophae COX1 features an atypical start codon (CGA); ATP6, COX1, ND1, ND4, ND4L, ND5, and ND6 exhibit incomplete stop codons completed in the mRNA by the addition of 3' A residues. Contrary to previous phylogenetic hypotheses, phylogenetic reconstruction places A. jatrophae as sister to nymphalid tribe Nymphalini.

It's a moth! It's a butterfly! It's the complete mitochondrial genome of the American moth-butterfly Macrosoma conifera (Warren, 1897) (Insecta: Lepidoptera: Hedylidae)!

The taxonomic placement of the moth-butterfly, Macrosoma conifera (Warren 1897) (Lepidoptera: Hedylidae), has been controversial. The 15,344 bp complete M. conifera circular mitogenome, assembled by genome skimming, consists of 81.7% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the typical butterfly gene order. Macrosoma conifera COX1 features an atypical CGA start codon while ATP6, COX1, COX2, and ND5 exhibit incomplete stop codons completed by the post-transcriptional addition of 3' A residues. Phylogenetic reconstruction places M. conifera as sister to the skippers (Hesperiidae), which is consistent with several recent phylogenetic analyses.

The complete mitochondrial genome of the Jackson's leaf butterfly Mallika jacksoni (Insecta: Lepidoptera: Nymphalidae)

The Jackson's leaf butterfly Mallika jacksoni (Sharpe 1896), is a leaf-mimicking species from tropical East Africa. Genome skimming by Illumina sequencing permitted the assembly of the complete circular M. jacksoni 15,183 bp mitogenome. It consists of 79.4% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs, and a control region in the typical butterfly gene order. Mallika jacksoni COX1 has a CGA start codon while ATP6, COX1, COX2, ND3, ND4, and ND5 exhibit partial stop codons completed by 3'-A residues added to the mRNA. Phylogenetic reconstruction places M. jacksoni as sister to Kallima within nymphalid tribe Kallimini.

The complete mitochondrial genome and phylogenetic analysis of the European map butterfly Araschnia levana (Insecta: Lepidoptera: Nymphalidae)

The European map butterfly Araschnia levana (Linnaeus, 1758) is a species showing extreme seasonal polyphenism. The complete 15,207 bp circular A. levana mitogenome consisting of 81.6% AT nucleotides, was assembled by Illumina genome skimming. It includes 22 tRNAs, 13 protein-coding genes, 2 rRNAs, and a control region in the typical butterfly gene order. Araschnia levana COX1 features an atypical CGA start codon and ATP6, COX1, COX2, ND1, ND3, and ND4 have incomplete stop codons completed by 3′A residues added to the mRNA. Phylogenetic reconstruction places A. levana as a basal lineage within tribe Nymphalini, consistent with previous phylogenetic hypotheses.

Beyond DNA barcoding: The unrealized potential of genome skim data in sample identification

Genetic tools are increasingly used to identify and discriminate between species. One key transition in this process was the recognition of the potential of the ca 658bp fragment of the organelle cytochrome c oxidase I (COI) as a barcode region, which revolutionized animal bioidentification and lead, among others, to the instigation of the Barcode of Life Database (BOLD), containing currently barcodes from >7.9 million specimens. Following this discovery, suggestions for other organellar regions and markers, and the primers with which to amplify them, have been continuously proposed. Most recently, the field has taken the leap from PCR-based generation of DNA references into shotgun sequencing-based "genome skimming" alternatives, with the ultimate goal of assembling organellar reference genomes. Unfortunately, in genome skimming approaches, much of the nuclear genome (as much as 99% of the sequence data) is discarded, which is not only wasteful, but can also limit the power of discrimination at, or below, the species level. Here, we advocate that the full shotgun sequence data can be used to assign an identity (that we term for convenience its "DNA-mark") for both voucher and query samples, without requiring any computationally intensive pretreatment (e.g. assembly) of reads. We argue that if reference databases are populated with such "DNA-marks," it will enable future DNA-based taxonomic identification to complement, or even replace PCR of barcodes with genome skimming, and we discuss how such methodology ultimately could enable identification to population, or even individual, level.

The complete mitochondrial genome of the brown pansy butterfly, Junonia stygia (Aurivillius, 1894), (Insecta: Lepidoptera: Nymphalidae)

The brown pansy, Junonia stygia (Aurivillius, 1894) (Lepidoptera: Nymphalidae), is a widespread West African forest butterfly. Genome skimming by Illumina sequencing allowed assembly of a complete 15,233 bp circular mitogenome from J. stygia consisting of 79.5% AT nucleotides. Mitochondrial gene order and composition is identical to other butterfly mitogenomes. Junonia stygia COX1 features an atypical CGA start codon, while ATP6, COX1, COX2, ND4, and ND4L exhibit incomplete stop codons. Phylogenetic reconstruction supports a monophyletic Subfamily Nymphalinae, Tribe Junoniini, and genus Junonia. The phylogenetic tree places Junonia iphita and J. stygia as basal mitogenome lineages sister to the remaining Junonia sequences.

First Description of the Adult Male of the Gall-Like Scale Insect Allokermes galliformis (Riley) (Hemiptera: Coccomorpha: Kermesidae)

The adult male of Allokermes galliformis (Riley, 1881) (Hemiptera: Coccomorpha: Kermesidae) is described for the first time in Colorado, United States of America. This scale insect species recently emerged as a significant pest of red oaks in Colorado through its causative role in drippy blight disease. A description and illustration of the adult male characterize its key external morphological characteristics.

Acari of Canada

Summaries of taxonomic knowledge are provided for all acarine groups in Canada, accompanied by references to relevant publications, changes in classification at the family level since 1979, and notes on biology relevant to estimating their diversity. Nearly 3000 described species from 269 families are recorded in the country, representing a 56% increase from the 1917 species reported by Lindquist et al. (1979). An additional 42 families are known from Canada only from material identified to family- or genus-level. Of the total 311 families known in Canada, 69 are newly recorded since 1979, excluding apparent new records due solely to classification changes. This substantial progress is most evident in Oribatida and Hydrachnidia, for which many regional checklists and family-level revisions have been published. Except for recent taxonomic leaps in a few other groups, particularly of symbiotic mites (Astigmata: feather mites; Mesostigmata: Rhinonyssidae), knowledge remains limited for most other taxa, for which most species records are unpublished and may require verification. Taxonomic revisions are greatly needed for a large majority of families in Canada. Based in part on species recorded in adjacent areas of the USA and on hosts known to be present here, we conservatively estimate that nearly 10,000 species of mites occur in Canada, but the actual number could be 15,000 or more. This means that at least 70% of Canada's mite fauna is yet unrecorded. Much work also remains to match existing molecular data with species names, as less than 10% of the ~7500 Barcode Index Numbers for Canadian mites in the Barcode of Life Database are associated with named species. Understudied hosts and terrestrial and aquatic habitats require investigation across Canada to uncover new species and to clarify geographic and ecological distributions of known species.

Advances in DNA Barcoding of Toxic Marine Organisms

There are more than 200,000 marine species worldwide. These include many important economic species, such as large yellow croaker, ribbonfish, tuna, and salmon, but also many potentially toxic species, such as blue-green algae, diatoms, cnidarians, ctenophores, Nassarius spp., and pufferfish. However, some edible and toxic species may look similar, and the correct identification of marine species is thus a major issue. The failure of traditional classification methods in certain species has promoted the use of DNA barcoding, which uses short, standard DNA fragments to assist with species identification. In this review, we summarize recent advances in DNA barcoding of toxic marine species such as jellyfish and pufferfish, using genes including cytochrome oxidase I gene (COI), cytochrome b gene (cytb), 16S rDNA, internal transcribed spacer (ITS), and Ribulose-1,5-bisphosphate carboxylase oxygenase gene (rbcL). We also discuss the application of this technique for improving the identification of marine species. The use of DNA barcoding can benefit the studies of biological diversity, biogeography, food safety, and the detection of both invasive and new species. However, the technique has limitations, particularly for the analysis of complex objects and the selection of standard DNA barcodes. The development of high-throughput methods may offer solutions to some of these issues.

The complete mitochondrial genome of the giant casemaker caddisfly Phryganea cinerea (Insecta: Trichoptera: Phryganeidae)

The rush sedge caddisfly Phryganea cinerea Walker, 1852 (Phryganeidae, the giant casemakers), is a widespread and adaptable North American caddisfly. Genome skimming by Illumina sequencing permitted the assembly of a complete 15,043 bp circular mitogenome from P. cinerea consisting of 78.2% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the ancestral insect gene order. Phryganea cinerea COX1 features an atypical CGA start codon and COX1, NAD1, NAD4, and NAD5 exhibit incomplete stop codons completed by the addition of 3' A residues to the mRNA. Phylogenetic reconstruction reveals a monophyletic Order Trichoptera and Family Phyrganeidae.