The complete mitochondrial genome of Papilio glaucus and its phylogenetic implications

Due to the intriguing morphology, lifecycle, and diversity of butterflies and moths, Lepidoptera are emerging as model organisms for the study of genetics, evolution and speciation. The progress of these studies relies on decoding Lepidoptera genomes, both nuclear and mitochondrial. Here we describe a protocol to obtain mitogenomes from Next Generation Sequencing reads performed for whole-genome sequencing and report the complete mitogenome of Papilio (Pterourus) glaucus. The circular mitogenome is 15,306 bp in length and rich in A and T. It contains 13 protein-coding genes (PCGs), 22 transfer-RNA-coding genes (tRNA), and 2 ribosomal-RNA-coding genes (rRNA), with a gene order typical for mitogenomes of Lepidoptera. We performed phylogenetic analyses based on PCG and RNA-coding genes or protein sequences using Bayesian Inference and Maximum Likelihood methods. The phylogenetic trees consistently show that among species with available mitogenomes Papilio glaucus is the closest to Papilio (Agehana) maraho from Asia.

The complete mitochondrial genome of the Orange Hairstreak Japonica lutea (Lepidoptera: Lycaenidae: Theclinae)

The complete mitochondrial genome of Japonica lutea is 15,225 bp in length, containing 37 typical insect genes: 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes and a non-coding AT-rich region. All the 13 PCGs are initiated with ATN, except for COI gene which is started by CGA. Nine PCGs use the complete termination codon (TAN), whereas the COI, COII, ND4 and ND5 genes end with single nucleotide T. In total, 131 bp intergenic spacers and 31 bp overlapping sequences are interspersed throughout the whole genome. The two rRNA genes (lrRNA and srRNA) are 1327 bp and 770 bp in size, with their AT contents of 87.8% and 85.5%, respectively. All tRNAs display typical secondary cloverleaf structures except for tRNA^Ser(AGN) which loses the DHU arm. The 401 bp long AT-rich region contains several features characteristic of the lepidopterans, such as the ATAGA motif followed by a 19 bp poly-T stretch, a microsatellite-like (AT)₇ element preceded by the ATTTA motif and a 9 bp poly-A stretch.

The complete mitochondrial genome of Parnassius cephalus (Lepidoptera: Papilionidae: Parnassinae)

The complete mitochondrial genome of Parnassius cephalus is 15,343 bp in length, containing 13 protein-coding genes (PCGs), 22 tRNA genes, 2 ribosomal RNA genes and a noncoding AT-rich region. All the 13 PCGs are initiated with the codon ATN, except for COI gene which starts with codon CGA. Eleven PCGs stop with the termination codon TAN, while the COI and COII genes end with single nucleotide T. All the tRNA genes have the typical secondary clover-leaf structures except tRNA^{Ser (AGN)}, which loses its DHU stem. The two rRNA genes (lrRNA and srRNA) are 1341 bp and 777 bp in length, with their AT contents being 83.75% and 85.33%, respectively. The AT-rich region is 487 bp in length, and contains some conservative structures similar to other butterfly mitogenomes, such as a 17 bp poly-T stretch preceded by the ATAGA motif, and a microsatellite-like (AT)₁₀ element preceded by the ATTTA motif.

The complete mitochondrial genome of Parnassius imperator (Lepidoptera: Papilionidae: Parnassiinae)

The complete mitochondrial genome (mitogenome) of Parnassius imperator (Lepidoptera: Parnassiinae) is a circular molecule of 15,424 bp in length, containing 37 typical insect mitochondrial genes and one non-coding A + T-rich region. Its gene order and arrangement are identical to the common type found in most lepidopteran mitogenomes. All protein-coding genes (PCGs) start with a typical ATN initiation codon, except for the cox1, which is initiated by the CGA codon as observed in other lepidopteran species. Some PCGs use standard TAA, while others use TAG (nad1) or incomplete codon T (cox1 and cox2), as their termination codons. 15 intergenic spacers (175 bp in total) and 10 overlapping sequences (29 bp in total) are dispersed throughout the whole genome. The 491 bp long A+ T-rich region contains some conserved structures similar to those found in other lepidopteran mitogenomes, such as the motif ATAGA followed by an 18-bp poly-T stretch, a microsatellite-like (AT)6 element preceded by the ATTTA motif. In addition, a 36 bp sequence stretch potential to form stem-loop structures is also found in the A+ T-rich region.

The complete mitochondrial genome of Callerebia suroia (Lepidoptera: Nymphalidae: Satyrinae)

The complete mitochondrial genome (mitogenome) of Callerebia suroia (Lepidoptera: Nymphalidae: Satyrinae) was determined and analyzed in this paper. The circular genome is 15,208 bp long, including 37 typical mitochondrial genes and one non-coding AT-rich region. All protein-coding genes (PCGs) started with ATN, except for COI gene with CGA(R), which is often found in other butterflies; nine PCGs harbor the typical stop codon TAA, whereas COI, COII, ND5 and ND4 end with a single T. All tRNA genes display typical secondary clover-leaf structures, except for tRNA(Ser)(AGN), whose dihydrouridine (DHU) arm is replaced by a simple loop. The lrRNA and srRNA genes are 1,347 bp and 753 bp in length, with their AT contents of 84.4% and 85.4%, respectively. The 417 bp AT-rich region contains non repetitive sequences, but harbor several features common to the lepidopterans, including the motif ATAGA followed by a 19-bp poly-T stretch and a microsatellite-like (TA)8 element preceded by the ATTTA motif.

Complete mitochondrial genomes of five skippers (Lepidoptera: Hesperiidae) and phylogenetic reconstruction of Lepidoptera

We sequenced mitogenomes of five skippers (family Hesperiidae, Lepidoptera) to obtain further insight into the characteristics of butterfly mitogenomes and performed phylogenetic reconstruction using all available gene sequences (PCGs, rRNAs, and tRNAs) from 85 species (20 families in eight superfamilies). The general genomic features found in the butterflies also were found in the five skippers: a high A+T composition (79.3%-80.9%), dominant usage of TAA stop codon, similar skewness pattern in both strands, consistently length intergenic spacer sequence between tRNA(Gln) and ND2 (64-87 bp), conserved ATACTAA motif between tRNA(Ser (UCN)) and ND1, and characteristic features of the A+T-rich region (the ATAGA motif, varying length of poly-T stretch, and poly-A stretch). The start codon for COI was CGA in four skippers as typical, but Lobocla bifasciatus evidently possessed canonical ATG as start codon. All species had the ancestral arrangement tRNA(Asn)/tRNA(Ser (AGN)), instead of the rearrangement tRNA(Ser (AGN))/tRNA(Asn), found in another skipper species (Erynnis). Phylogenetic analyses using all available genes (PCGs, rRNAS, and tRNAs) yielded the consensus superfamilial relationships ((((((Bombycoidea+Noctuoidea+Geometroidea)+Pyraloidea)+Papilionoidea)+Tortricoidea)+Yponomeutoidea)+Hepialoidea), confirming the validity of Macroheterocera (Bombycoidea, Noctuoidea, and Geometroidea in this study) and its sister relationship to Pyraloidea. Within Rhopalocera (butterflies and skippers) the familial relationships (Papilionidae+(Hesperiidae+(Pieridae+((Lycaenidae+Riodinidae)+Nymphalidae)))) were strongly supported in all analyses (0.98-1 by BI and 96-100 by ML methods), rendering invalid the superfamily status for Hesperioidea. On the other hand, current mitogenome-based phylogeny did not find consistent superfamilial relationships among Noctuoidea, Geometroidea, and Bombycoidea and the familial relationships within Bombycoidea between analyses, requiring further taxon sampling in future studies.

The complete mitochondrial genome of Tirumala limniace (Lepidoptera: Nymphalidae: Danainae)

The complete mitochondrial nucleotide sequence of Tirumala limniace is 15,285 bp in size, containing typical metazoan 37 genes: 13 protein-coding genes (PCGs), 22tRNA genes, 2 ribosomal RNA genes and one noncoding AT-rich region. All the 13 PCGs initiated with ATN, except for COI gene which is started by CGA codon. Nine PCGs use the complete termination codon (TAA), whereas the COI, COII, ND4 and ND5 genes end with single T. A total of 132 bp intergenic spacers and a total of 37 bp overlapping sequences are interspersed throughout the whole genome. The two rRNA genes (rrnL and rrnS) are 1352 bp and 779 bp in size, with their AT contents of 84.6% and 85.5%, respectively. All tRNA genes display typical secondary cloverleaf structures except for trnS1 (AGN) which loses DHU arm. The 438 bp long AT-rich region contains several features common to the other lepidopterans, such as the ATAGA motif followed by a 18 bp poly-T stretch, a 9 bp poly-T stretch, a 10 bp poly-A stretch and some microsatellite-like (AT)n elements.

The complete mitochondrial genome of the Daimio tethys (Lepidoptera: Hesperoidea: Hesperiidae)

The complete mitochondrial genome of Daimio tethys (Hesperoidea: Hesperiidae) is a circular molecule of 15,341 bp in length, containing 37 typical animal mitochondrial genes: 13 protein coding genes (ATP6, ATP8, COI-III, ND1-6, ND4L, Cytb), 2 rRNA genes, 22 tRNA genes and a non-coding AT-rich region. Its gene order and content are identical to all other available butterfly mitogenomes. All PCGs initiate with typical ATN codons, except for COI, which is initiated by the CGA codon as observed in other butterfly species. Ten PCGs use complete termination codons TAA or TAG, whereas the COI, COII and ND5 genes end with a single T. A total of 179 bp of intergenic spacers are interspersed in 11 regions, ranging in size from 1 to 82 bp. The AT-rich region is 415 bp long and contains some conserved structures characteristic of the lepidopteran mitogenomes, including the motif ATAGA followed by a 17 bp poly-T stretch and a microsatellite-like (AT)8 element preceded by the ATTA motif.

The complete mitogenome of Apocheima cinerarius (Lepidoptera: Geometridae: Ennominae) and comparison with that of other lepidopteran insects

The complete mitochondrial genome (mitogenome) of a female flightless geometrid moth Apocheima cinerarius was found to be 15,722 bp in length, containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a control region. The A+T content of the complete mitogenome is 80.83%. The AT skew value ([A-T]/[A+T]) is 0.027. The 13 PCGs of the mitogenome start with typical ATN codons, except for cox1 with the start codon CGA. All the tRNA genes have typical cloverleaf secondary structures, except for trnSer(AGN). The secondary structures of rrnL and rrnS were predicted. Six structural domains including conserved regions (IV, V) and variable regions (I, II, III, VI) were identified in the secondary structure of rrnL. The secondary structure of rrnS consists of 3 structural domains. The control region of A. cinerarius begins with conserved motifs of "ATAGA"+19-bp poly T. It also contains a microsatellite-like (TA)26, a stem-and-loop structure, and a poly-A stretch. Phylogenetic analysis showed that Geometroidea is more closely related to Bombycoidea than to Noctuoidea. A. cinerarius is more closely related to Biston panterinaria than to Phthonandria atrilineata, which is in accordance with the conventional morphology-based classification.

Mitogenomic sequences effectively recover relationships within brush-footed butterflies (Lepidoptera: Nymphalidae)

BACKGROUND

Mitogenomic phylogenies have revealed well-supported relationships for many eukaryote groups. In the order Lepidoptera, 113 species mitogenomes had been sequenced (May 14, 2014). However, these data are restricted to ten of the forty-three recognised superfamilies, while it has been challenging to recover large numbers of mitogenomes due to the time and cost required for primer design and sequencing. Nuclear rather than mitochondrial genes have been preferred to reconstruct deep-level lepidopteran phylogenies, without seriously evaluating the potential of entire mitogenomes. Next-generation sequencing methods remove these limitations by providing efficiently massive amounts of sequence data. In the present study, we simultaneously obtained a large number of nymphalid butterfly mitogenomes to evaluate the utility of mitogenomic phylogenies by comparing reconstructions to the now quite well established phylogeny of Nymphalidae.

RESULTS

We newly obtained 30 nymphalid mitogenomes via pyrosequencing on the Roche 454 GS Junior system, and combined these sequences with publicly accessible data to provide a 70-taxa dataset covering 37 genes for a 15,495 bp alignment. Polymorphic sites were not homogeneously distributed across the gene. Two gene regions, nad6 and 3' end of nad5, were most variable, whereas the cox1 and 5' ends of rrnL were most conserved. Phylogenetic relationships inferred by two likelihood methods were congruent and strongly supported (>0.95 posterior probability; ML bootstrap >85%), across the majority of nodes for multiple partitioning strategies and substitution models. Bayes factor results showed that the most highly partitioned dataset is the preferred strategy among different partitioning schemes. The most striking phylogenetic findings were that the subfamily Danainae not Libytheinae was sister of the remaining brush-footed butterflies and that, within Limenitidini, the genus Athyma was clearly polyphyletic. None of the single-gene phylogenies recovered the highly supported topologies generated on the basis of the whole mitogenomic data.

CONCLUSIONS

Thirty mitogenomes were assembled with 89% completeness from the contigs of pyrosequencing-derived reads. Entire mitogenomes or higher-quality sequences could be obtained by increasing pyrosequencing read coverage or by additional Sanger sequencing. Our mitogenomic phylogenies provide robust nodal support at a range of levels, demonstrating that mitogenomes are both accurate and efficient molecular markers for inferring butterfly phylogeny.

The complete mitochondrial genome of the Byasa alcinous (Lepidoptera: Papilionidae: Papilioninae)

The complete mitochondrial genome (mitogenome) of Byasa alcinous (Lepidoptera: Papilionidae: Papilioninae) is a circular molecule of 15,266 bp in length, containing 37 typical insect mitochondrial genes: 13 protein coding genes (PCGs), 2 rRNA genes, 22 tRNA genes and a non-coding AT-rich region. Its gene order and arrangement are identical to all other available butterfly mitogenomes. All PCGs start with a typical ATN initiation codon, except for COI, which is initiated by the CGA codon as observed in other butterfly species. Ten PCGs terminate in the complete stop codon TAA or TAG, whereas the COI, COII and ND4 genes end with single T. Ten intergenic spacers (73 bp in total), and 12 overlapping regions (28 bp in total) are dispersed throughout the whole genome. The non-coding AT-rich region is 405 bp long and contains some conserved structures similar to those found in other butterfly mitogenomes, such as the motif ATAGA followed by a 12-bp poly-T stretch and a microsatellite-like (AT)14 element preceded by the ATTTA motif. Additionally, a 11-bp poly-T sequences and a microsatellite-like (AT)7 repeated elements are detected in this region.

The complete mitochondrial genome of the Pazala timur (Lepidoptera: Papilionidae: Papilioninae)

The complete mitochondrial genome of Pazala timur (Lepidoptera: Papilionodae) is a circular molecule of 15,226 bp in length, containing 37 typical animal mitochondrial genes: 13 protein coding genes, 2 rRNA genes, 22 tRNA genes and a non-coding AT-rich region. Its gene order and arrangement are identical to all other available butterfly mitogenomes. All PCGs initiate with typical ATN codons, except for COI, which is initiated by the CGA codon. Ten PCGs use complete termination codon (TAA), whereas the COI, COII and ND5 genes end with single T. Twelve intergenic spacers (82 bp in total), and 11 overlapping regions (30 bp in total) are dispersed throughout the whole genome. The non-coding AT-rich region is 403 bp long and contains some conserved structures characteristic of the butterfly mitogenomes, such as the motif ATAGA followed by a 13-bp poly-T stretch and a microsatellite-like (AT)12 element preceded by the ATTTA motif.

The complete mitochondrial genome of Triphysa phryne (Lepidoptera: Nymphalidae: Satyrinae)

The complete mitochondrial genome (mitogenome) sequence of Triphysa phryne (Lepidoptera: Nymphalidae: Satyrinae) was determined in this study. The mitogenome is 15,143 bp in length, containing 37 typical animal mitochondrial genes: 13 putative protein-coding genes (PCGs), 2 ribosomal RNAs, 22 transfer RNAs and a non-coding AT-rich region. Its gene content and order are identical to those of other lepidopteran mitogenomes. All protein-coding genes (PCGs) are initiated by ATN codons, except for COI gene which uses CGA as its start codon. Nine PCGs terminate in the common stop TAA, whereas the COI, COII, ND5 and ND4 genes end with single T. All tRNA genes showed typical secondary cloverleaf structures except for the tRNA(Ser)(AGN), which has a simple loop with the absence of its DHU stem. The 316 bp AT-rich region contains several features common to the other lepidopterans, such as the motif ATAGA followed by an 19-bp poly-T stretch and two microsatellite-like (TA)8(AT) and (TA)4 elements preceded by the ATTTA motif.

The complete mitochondrial genome of Ideopsis similis (Lepidoptera: Nymphalidae: Danainae)

The complete mitochondrial nucleotide sequence of Ideopsis similis is 15,200 bp in size, containing typical metazoan 37 genes: 13 protein-coding genes (PCGs), 22 tRNA genes, 2 ribosomal RNA genes and 1 non-coding AT-rich region. All the 13 PCGs initiated with ATN, except for COI gene which started by CGA codon. Nine PCGs used the complete termination codon (TAA), whereas the COI, COII, ND4 and ND5 genes ended with single T. The two rRNA genes (rrnL and rrnS) were 1318 bp and 786 bp in size, with their AT contents of 84.7% and 85.7%, respectively. All tRNA genes display typical secondary cloverleaf structures except for trnS1(AGN) which loses DHU arm. The 404 bp long AT-rich region contains several features common to the other lepidopterans, such as the ATAGA motif followed by a 19 bp poly-T stretch, a 9 bp poly-T stretch and some microsatellite-like (AT)n elements.

The complete mitochondrial genome of Eurema hecabe (Lepidoptera: Pieridae: Coliadinae)

The complete mitochondrial genome (mitogenome) of Linnaeus Eurema hecabe (Lepidoptera: Pieridae: Coliadinae) is determined to be 15,160 bp in length, including 37 typical mitochondrial genes and an AT-rich region. Its gene order and orientation are identical to those of other butterfly species. All PCGs are initiated by typical ATN codons, except for CO1 gene which is started by CAG codon. Nine genes use complete termination codon (TAA), whereas the CO1, CO2, ND4 and ND5 genes end with single T. The two rRNA genes (rrnL and rrnS) are 1322 and 832 bp respectively; except for trnS1(AGN), all tRNA genes display typical secondary cloverleaf structures as those of other insects. The 315 bp long AT-rich region contains several features common to the other lepidopterans, such as the ATAGA motif followed by a 19 bp poly-T stretch, two microsatellite-like (TAA)5 and (AT)6 elements, a 9 bp poly-A stretch immediately upstream of trnM gene.

The complete mitochondrial genome of Gonepteryx rhamni (Lepidoptera: Pieridae: Coliadinae)

The complete mitochondrial genome (mitogenome) of Linnaeus Gonepteryx rhamni (Lepidoptera: Pieridae: Coliadinae) is a circular molecule of 15,023 bp in length, containing 37 typical coding genes and one non-coding AT-rich region. Its gene order and content are identical to the common type found in most insect mitogenomes. All protein coding genes (PCGs) start with a typical ATN initiation codon, except for the cox1, which use CGA as its start codon. Nine genes use standard complete termination codon (TAA), whereas the cox1, cox2, nad4 and nad5 genes end with single T. Except for trnS1(AGN), all tRNA genes display typical secondary cloverleaf structures as those of other insects. Additionally, the 371 bp long AT-rich region contains a few structures common to the other lepidopterons, such as the motif ATAGA followed by a 17 bp poly-T stretch, a microsatellite-like (AT)10 element preceded by the ATTTA motif, and a 10 bp poly-A presented immediately upstream of trnM gene.

The complete mitochondrial genomes of the Fenton's wood white, Leptidea morsei, and the lemon emigrant, Catopsilia pomona

The complete mitochondrial genomes of Leptidea morsei Fenton (Lepidoptera: Pieridae: Dis-morphiinae) and Catopsilia pomona (F.) (Lepidoptera: Pieridae: Coliadinae) were determined to be 15,122 and 15,142 bp in length, respectively, with that of L. morsei being the smallest among all known butterflies. Both mitogenomes contained 37 genes and an A+T-rich region, with the gene order identical to those of other butterflies, except for the presence of a tRNA-like insertion, tRNA(Leu) (UUR), in C. pomona. The nucleotide compositions of both genomes were higher in A and T (80.2% for L. morsei and 81.3% for C. pomona) than C and G; the A+T bias had a significant effect on the codon usage and the amino acid composition. The protein-coding genes utilized the standard mitochondrial start codon ATN, except the COI gene using CGA as the initiation codon, as reported in other butterflies. The intergenic spacer sequence between the tRNA(Ser) (UCN) and ND1 genes contained the ATACTAA motif. The A+T-rich region harbored a poly-T stretch and a conserved ATAGA motif located at the end of the region. In addition, there was a triplicated 23 bp repeat and a microsatellite-like (TA)9(AT)3 element in the A+T-rich region of the L. morsei mitogenome, while in C. pomona, there was a duplicated 24 bp repeat element and a microsatellite-like (TA)9 element. The phylogenetic trees of the main butterfly lineages (Hesperiidae, Papilionidae, Pieridae, Nymphalidae, Lycaenidae, and Riodinidae) were reconstructed with maximum likelihood and Bayesian inference methods based on the 13 concatenated nucleotide sequences of protein-coding genes, and both trees showed that the Pieridae family is sister to Lycaenidae. Although this result contradicts the traditional morphologically based views, it agrees with other recent studies based on mitochondrial genomic data.