Phylogenetic analysis of Zygaenoidea small-subunit rRNA structural variation implies initial oligophagy on cyanogenic host plants in larvae of the moth genus Zygaena (Insecta: Lepidoptera)

Cyanogenesis, the release of toxic cyanide from living cells, plays an important role in the defence system of certain plant (e.g. Fabaceae) and animal (e.g. Zygaenidae) taxa. The larvae of a significant number of Zygaena moth species (Zygaenidae) preferentially feed on cyanogenic Fabaceae and some of them are able to sequester cyanogenic compounds of their host plants. Using secondary structure variation of the small-subunit rRNA, we tested the currently accepted evolutionary hypothesis explaining species diversification in the genus Zygaena . We derived secondary structures considering evidence from covariation patterns and thermodynamic folding and applied structural information in a phylogenetic analysis. Contrary to previous assumptions, our results suggest that the use of cyanogenic larval host plants is an ancient trait and that the ability to feed on cyanogenic plants was probably already present in the most recent common ancestor of Zygaena . The utilization of acyanogenic plants in Zygaena species appears to be the result of a single secondary, reverse, larval host-plant shift. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 147 , 367–381.     

Congruence between molecular phylogeny and cuticular design in Echiniscoidea (Tardigrada,Heterotardigrada)

Although morphological characters distinguishing echiniscid genera and species are well understood, the phylogenetic relationships of these taxa are not well established. We thus investigated the phylogeny of Echiniscidae, assessed the monophyly of Echiniscus, and explored the value of cuticular ornamentation as a phylogenetic character within Echiniscus. To do this, DNA was extracted from single individuals for multiple Echiniscus species, and 18S and 28S rRNA gene fragments were sequenced. Each specimen was photographed, and published in an open database prior to DNA extraction, to make morphological evidence available for future inquiries. An updated phylogeny of the class Heterotardigrada is provided, and conflict between the obtained molecular trees and the distribution of dorsal plates among echiniscid genera is highlighted. The monophyly of Echiniscus was corroborated by the data, with the recent genus Diploechiniscus inferred as its sister group, and Testechiniscus as the sister group of this assemblage. Three groups that closely correspond to specific types of cuticular design in Echiniscus have been found with a parsimony network constructed with 18S rRNA data. © 2013 The Linnean Society of London     

The complete mitochondrial genome of Eterusia aedea (Lepidoptera,Zygaenidae) and comparison with other zygaenid moths

Zygaenidae comprises >1036 species, including many folivorous pests in agriculture. In the present study, the complete mitochondrial genome (mitogenome) of a major pest of tea trees, Eterusia aedea was determined. The 15,196-bp circular genome contained the common set of 37 mitochondrial genes (including 13 protein-coding genes, two rRNA genes, and 22 tRNA genes) and exhibited the similar genomic features to reported Zygaenidae mitogenome. Comparative analyses of Zygaenidae mitogenomes showed a typical evolutionary trend of lepidopteran mitogenomes. In addition, we also investigated the gene order of lepidopteran mitogenomes and proposed that the novel gene order trnA-trnR-trnN-trnE-trnS-trnF from Zygaenidae and Gelechiidae and most other gene rearrangements of this tRNA cluster evolved independently. Finally, the mitogenomic phylogeny of Lepidoptera was reconstructed based on multiple mitochondrial datasets. And all the phylogenetic results revealed the sister relationships of Cossoidea and Zygaenoidea with both BI and ML methods, which is the first stable mitogenomic evidence for this clade.     

Molecular systematics of the South American caviomorph rodents: relationships among species and genera in the family Octodontidae

Nucleotide sequences from mitochondrial (12S rRNA) and nuclear (growth hormone receptor) genes were used to investigate phylogenetic relationships among South American hystricognath rodents of the superfamily Octodontoidea, with special emphasis on the family Octodontidae. Relationships among most taxa were well resolved by a combined analysis of both genes, and the molecular phylogeny was used to address several long-standing phylogenetic problems. The family Abrocomidae was the most basal lineage within the superfamily Octodontoidea, sensu stricto, and the family Ctenomyidae was sister to the family Octodontidae, followed by a monophyletic group containing the families Myocastoridae and Echimyidae. A basic dichotomy was observed within the family Octodontidae. The Argentine desert specialists, Tympanoctomys and Octomys, grouped separate from Octodontomys, which was sister to a clade containing a monophyletic Octodon and a clade represented by species of Aconaemys and Spalacopus. Aconaemys was paraphyletic relative to Spalacopus. The phylogeny was used as an interpretive framework for an examination of variation in several non-molecular characters. The primitive diploid number for most of the octodontoids was determined to be between 46 and 56, and the primitive genome size 8.2 pg. Members of the Octodontidae appeared to be derived from an ancestral stock occupying lower elevations in scrub habitat. Furthermore, estimates of divergence time from the molecular data provided a temporal perspective for changes in plant communities, which demonstrated turnover and diversification in response to climatic and geologic events occurring in the Miocene through the Pleistocene.     

The internal female genitalia of some Zygaenidae (Insecta,Lepidoptera): their morphology and remarks on their phylogenetie significance*

The internal female genitalia of fifteen species of Zygaenidae (representing seven genera of Zygaeninae), one species of Heterogynidae and one species of Limacodidae have been studied in order to delimit the distribution of Petersen's glands within the Zygaenidae. The study demonstrates a considerable amount of structural variation. Petersen's glands are found to represent an autapomorphic character of the Zygaeninae, while the pseudobursa is restricted to the Zygaenini. Most likely it is an autapomorphic character of this tribe. Some other characters that were studied are discussed with special reference to their usefulness for a reconstruction of the phylogeny of the Zygaenidae.     

Molecular phylogeny of the family Tephritidae (Insecta: Diptera): New insight from combined analysis of the mitochondrial 12S, 16S,and COII genes

The phylogeny of the family Tephritidae (Diptera: Tephritidae) was reconstructed from mitochondrial 12S, 16S, and COII gene fragments using 87 species, including 79 tephritid and 8 outgroup species. Minimum evolution and Bayesian trees suggested the following phylogenetic relationships: (1) A sister group relationship between Ortalotrypeta and Tachinisca, and their basal phylogenetic position within Tephritidae; (2) a sister group relationship between the tribe Acanthonevrini and Phytalmiini; (3) monophyly of Plioreocepta, Taomyia and an undescribed new genus, and their sister group relationship with the subfamily Tephritinae; (4) a possible sister group relationship of Cephalophysa and Adramini; and (5) reconfirmation of monophyly for Trypetini, Carpomyini, Tephritinae, and Dacinae. The combination of 12S, 16S, and COII data enabled resolution of phylogenetic relationships among the higher taxa of Tephritidae.     

Exploring the potential of small RNA subunit and ITS sequences for resolving phylogenetic relationships within the phylum Ctenophora

Ctenophores are a phylum of non-bilaterian marine (mostly planktonic) animals, characterised by several unique synapomorphies (e.g., comb rows, apical organ). Relationships between and within the nine recognised ctenophore orders are far from understood, notably due to a paucity of phylogenetically informative anatomical characters. Previous attempts to address ctenophore phylogeny using molecular data (18S rRNA) led to poorly resolved trees but demonstrated the paraphyly of the order Cydippida. Here we compiled an updated 18S rRNA data set, notably including a few newly sequenced species representing previously unsampled families (Lampeidae, Euryhamphaeidae), and we constructed an additional more rapidly evolving ITS1 + 5.8S rRNA + ITS2 alignment. These data sets were analysed separately and in combination under a probabilistic framework, using different methods (maximum likelihood, Bayesian inference) and models (e.g., doublet model to accommodate secondary structure; data partitioning). An important lesson from our exploration of these datasets is that the fast-evolving internal transcribed spacer (ITS) regions are useful markers for reconstructing high-level relationships within ctenophores. Our results confirm the paraphyly of the order Cydippida (and thus a “cydippid-like” ctenophore common ancestor) and suggest that the family Mertensiidae could be the sister group of all other ctenophores. The family Lampeidae (also part of the former “Cydippida”) is probably the sister group of the order Platyctenida (benthic ctenophores). The order Beroida might not be monophyletic, due to the position of Beroe abyssicola outside of a clade grouping the other Beroe species and members of the “Cydippida” family Haeckeliidae. Many relationships (e.g. between Pleurobrachiidae, Beroida, Cestida, Lobata, Thalassocalycida) remain unresolved. Future progress in understanding ctenophore phylogeny will come from the use of additional rapidly evolving markers and improvement of taxonomic sampling.     

Phylogeny and systematic position of Opiliones: a combined analysis of chelicerate relationships using morphological and molecular data

The ordinal level phylogeny of the Arachnida and the suprafamilial level phylogeny of the Opiliones were studied on the basis of a combined analysis of 253 morphological characters, the complete sequence of the 18S rRNA gene, and the D3 region of the 28S rRNA gene. Molecular data were collected for 63 terminal taxa. Morphological data were collected for 35 exemplar taxa of Opiliones, but groundplans were applied to some of the remaining chelicerate groups. Six extinct terminals, including Paleozoic scorpions, are scored for morphological characters. The data were analyzed using strict parsimony for the morphological data matrix and via direct optimization for the molecular and combined data matrices. A sensitivity analysis of 15 parameter sets was undertaken, and character congruence was used as the optimality criterion to choose among competing hypotheses. The results obtained are unstable for the high-level chelicerate relationships (except for Tetrapulmonata, Pedipalpi, and Camarostomata), and the sister group of the Opiliones is not clearly established, although the monophyly of Dromopoda is supported under many parameter sets. However, the internal phylogeny of the Opiliones is robust to parameter choice and allows the discarding of previous hypotheses of opilionid phylogeny such as the "Cyphopalpatores" or "Palpatores." The topology obtained is congruent with the previous hypothesis of "Palpatores" paraphyly as follows: (Cyphophthalmi (Eupnoi (Dyspnoi + Laniatores))). Resolution within the Eupnoi, Dyspnoi, and Laniatores (the latter two united as Dyspnolaniatores nov.) is also stable to the superfamily level, permitting a new classification system for the Opiliones.     

Reconstruction of phylogenetic relationships within Grapsidae (Crustacea: Brachyura) and comparison of trans-isthmian versus amphi-atlantic gene flow based on mtDNA

Following taxonomic revisions in recent years, the originally large family Grapsidae MacLeay, 1838 has become a relatively small and morphologically homogeneous family in terms of adult and larval morphology. Most available molecular studies including more than one genus of the family have also suggested monophyly of the corresponding taxa. However, no single phylogenetic study has ever included all constituent genera of the Grapsidae. In the current study, a molecular phylogeny based on sequences of the mitochondrial 16S rRNA gene from all eight grapsid genera and 34 species is presented and suggests that up to four genera are not monophyletic. This is mainly due to the polyphyletic nature of the genus Pachygrapsus which can be found in six different lineages of the phylogeny, suggesting that the genus currently does not represent a single evolutionary lineage and is in need of taxonomic revision. Amphi-atlantic and trans-isthmian species pairs or populations in four genera are compared and reveal relatively constant and pronounced divergences across the Panama Isthmus as opposed to moderate divergences across the Atlantic Ocean, thereby suggesting occurrence of gene flow across the Atlantic Ocean during the past three million years.