Evolutionary history of Stratiomyidae (Insecta: Diptera): the molecular phylogeny of a diverse family of flies

Stratiomyidae is a cosmopolitan family of Brachycera (Diptera) that contains over 2800 species. This study focused on the relationships of members of the subfamily Clitellariinae, which has had a complicated taxonomic history. To investigate the monophyly of the Clitellariinae, the relationships of its genera, and the ages of Stratiomyidae lineages, representatives for all 12 subfamilies of Stratiomyidae, totaling 68 taxa, were included in a phylogenetic reconstruction. A Xylomyidae representative, Solva sp., was used as an outgroup. Sequences of EF-1alpha and 28S rRNA genes were analyzed under maximum parsimony with bootstrapping, and Bayesian methods to recover the best estimate of phylogeny. A chronogram with estimated dates for all nodes in the phylogeny was generated with the program, r8s, and divergence dates and confidence intervals were further explored with the program, multidivtime. All subfamilies of Stratiomyidae with more than one representative were found to be monophyletic, except for Stratiomyinae and Clitellariinae. Clitellariinae were distributed among five separate clades in the phylogeny, and Raphiocerinae were nested within Stratiomyinae. Dating analysis suggested an early Cretaceous origin for the common ancestor of extant Stratiomyidae, and a radiation of several major Stratiomyidae lineages in the Late Cretaceous.     

A molecular phylogeny of warbling-finches (Poospiza): paraphyly in a neotropical Emberizid genus

We investigated the phylogenetic relationships of 12 species within a single genus of neotropical passerine (Poospiza) using 849 bp (283 codons) of the cytochrome b mitochondrial gene. We further explored evolutionary affinities of these taxa using sequence from an additional 47 thraupine (tanagers) and 7 emberizine (sparrows and buntings) genera, members of the predominantly New World family Emberizidae. Poospiza have traditionally been considered part of the emberizine radiation. However, our analyses suggest that members of this genus are more closely related to some thraupine lineages than they are to the other neotropical emberizine genera included in our study (Atlapetes, Embernagra, Melopyrrha, Phrygilus, Saltatricula, Tiaris). Although member taxa are closely related, the genus Poospiza appears to be paraphyletic with representatives of 6 thraupine genera (Cnemoscopus, Cypsnagra, Hemispingus, Nephelornis, Pyrrhocoma, Thylpopsis) interspersed among four well-supported Poospiza clades. The majority of species within this Poospiza-thraupine clade have geographic ranges that are exclusive to, or partially overlap with, the Andes Mountains. It is probable that these mountains have played an important role in driving cladogenesis within this group. Sequence divergence (transversions only; mean 4.7+/-1.3%) within the clade suggests that much of this diversification occurred within the late Miocene and Pliocene, a period coincident with major orogenic activity in central-western South America.     

A molecular phylogeny of the neotropical butterfly genus Anartia (Lepidoptera: Nymphalidae)

While Anartia butterflies have served as model organisms for research on the genetics of speciation, no phylogeny has been published to describe interspecific relationships. Here, we present a molecular phylogenetic analysis of Anartia species relationships, using both mitochondrial and nuclear genes. Analyses of both data sets confirm earlier predictions of sister species pairings based primarily on genital morphology. Yet both the mitochondrial and nuclear gene phylogenies demonstrate that Anartia jatrophae is not sister to all other Anartia species, but rather that it is sister to the Anartia fatima-Anartia amathea lineage. Traditional biogeographic explanations for speciation across the genus relied on A. jatrophae being sister to its congeners. These explanations invoked allopatric divergence of sister species pairs and multiple sympatric speciation events to explain why A. jatrophae flies alongside all its congeners. The molecular phylogenies are more consistent with lineage divergence due to vicariance, and range expansion of A. jatrophae to explain its sympatry with congeners. Further interpretations of the tree topologies also suggest how morphological evolution and eco-geographic adaptation may have set species range boundaries.     

Heterochrony during skeletal development of Pseudis platensis (anura,hylidae) and the early offset of skeleton development and growth

The aquatic frog Pseudis platensis has a giant tadpole, long developmental time, and dissociated metamorphic events that include later offset of larval somatic morphologies. Moreover, when the tadpole metamorphoses, the young frog is nearly the size of an adult, suggesting that this species has low rates of postmetamorphic growth. Herein, we study the development of the skeleton during larval development up to the end of metamorphosis, which is denoted by the complete lost of the tail in P. platensis. Our study revealed heterochronic differences in skeletal development compared with that of most anurans; these involve the complete differentiation of skull bones and the extensive ossification of the postcranial skeleton before completion of metamorphosis. The skull of metamorphosing P. platensis has an ossified sphenethmoid and a fully formed plectral apparatus, thus differing with regard to the pattern observed in most anurans in which both developmental events take place during the postmetamorphic life. Despite the fact that the iliosacral articulation and the urostyle are present at the end of metamorphosis as in most anurans, ossification/calcification of carpus, tarsus, and limb epihyses during metamorphosis of P. platensis suggests that the postcranial skeleton lacks postmetamorphic growth. This study also includes a discussion of the pattern of development of the plectral apparatus, which allows us to propose a new hypothesis regarding pars externa plectri homology. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

Untangling the phylogeny of neotropical lianas (Bignonieae, Bignoniaceae)

The tribe Bignonieae (Bignoniaceae) is a large and morphologically diverse clade of neotropical lianas. Despite being a conspicuous component of the neotropical flora, the systematics of the tribe has remained uncertain due to confusing patterns of morphological variation within the group. Chloroplast (ndhF) and nuclear (PepC) DNA sequences were used here to reconstruct the phylogeny of Bignonieae. Individual analyses of ndhF and PepC were highly similar to one another, yet localized differences in the placement of six species suggests some conflict between data sets. Combined analyses result in trees that are consistent with those from the individual analyses and provide greater support for the suggested relationships. This phylogeny provides important new insights into the systematics of the tribe. It identifies 21 strongly supported species groups, eight of which broadly correspond to currently recognized genera. In addition, each of these 21 species groups is supported by morphological synapomorphies. The consistency between morphological and molecular data suggests that the current phylogeny provides a solid framework for a formal revision of the generic-level classification and for addressing other aspects of the biology of Bignonieae.     

MtDNA phylogeny and biogeography of Copelatinae, a highly diverse group of tropical diving beetles (Dytiscidae)

Copelatinae is a diverse lineage of diving beetles (Dytiscidae) frequently encountered in wet tropical and subtropical forests, but phylogenetic relationships are very poorly understood. We performed a phylogenetic and biogeographic analysis of this worldwide distributed group based on 50 species including a representative sample of major taxonomic groups and biogeographical regions. DNA sequences were obtained for the mitochondrial genes cytochrome oxidase I, cytochrome b, and 16S rRNA, for a total of 1575 aligned nucleotide positions. We found Copelatinae to be monophyletic, placed in a derived position and not sister to all remaining dytiscids, as had been suggested by earlier authors. The largest genus, Copelatus with some 460 known species was paraphyletic with respect to the smaller genera Lacconectus and Aglymbus. Among the major lineages of Copelatus, the subgenus Papuadytes was consistently recovered as sister to all other species (including Lacconectus and Aglymbus) with the possible exception of two western Palearctic taxa. We propose that the subgenus Papuadytes is removed from Copelatus and assigned generic status. Likewise, the two western Palearctic Copelatus are removed from this genus, and assigned the available genus name Liopterus. Our best phylogenetic hypothesis retrieved Afrotropical and New Guinean plus Australian species of Copelatus as monophyletic. Asian species were paraphyletic with respect to a species from Sulawesi which grouped with the species from New Guinea. Asian species were also paraphyletic with respect to Oriental Lacconectus, which was grouped with a clade of Neotropical species. Neotropical Copelatus form at least two separate lineages. The biogeographical evolution of Papuadytes is consistent with the relative age of the landmasses in the Austral region. Basal species are Australian, and successively derived ones are from New Caledonia and New Guinea. One species apparently dispersed from New Caledonia to China. Assuming a molecular clock and using a standard calibration of 2% divergence/MY the origin of Copelatinae is estimated to be between 85 and 95 MY.     

Morphology and molecular phylogeny of Pseudotrichonympha hertwigi and Pseudotrichonympha paulistana (Trichonymphea, parabasalia) from neotropical rhinotermitids

Pseudotrichonympha is a large hypermastigote parabasalian found in the hindgut of several species of rhinotermitid termites. The genus was discovered more than 100 years ago, and although over a dozen species have since been described, this represents only a small fraction of its likely diversity: the termite genera from which Pseudotrichonympha is known are all species rich, and in most cases their hindgut symbionts have not been examined. Even formally described species are mostly lacking in detailed microscopic data and/or sequence data. Using small subunit ribosomal RNA gene sequences and light and scanning electron microscopy we describe here the morphology and molecular phylogenetic position of two Pseudotrichonympha species: the type species for the genus, Pseudotrichonympha hertwigi from Coptotermes testaceus (described previously in line drawing only), and Pseudotrichonympha paulistana from Heterotermes tenuis (described previously based on light microscopy only).     

Biogeography and evolution of body size and life history of African frogs: phylogeny of squeakers (Arthroleptis) and long-fingered frogs (Cardioglossa) estimated from mitochondrial data

The evolutionary history of living African amphibians remains poorly understood. This study estimates the phylogeny within the frog genera Arthroleptis and Cardioglossa using approximately 2400 bases of mtDNA sequence data (12S, tRNA-Valine, and 16S genes) from half of the described species. Analyses are conducted using parsimony, maximum likelihood, and Bayesian methods. The effect of alignment on phylogeny estimation is explored by separately analyzing alignments generated with different gap costs and a consensus alignment. The consensus alignment results in species paraphyly, low nodal support, and incongruence with the results based on other alignments, which produced largely similar results. Most nodes in the phylogeny are highly supported, yet several topologies are inconsistent with previous hypotheses. The monophyly of Cardioglossa and of miniature species previously assigned to Schoutedenella was further examined using Templeton and Shimodaira–Hasegawa tests. Cardioglossa monophyly is rejected and C. aureoli is transferred to Arthroleptis. These tests do not reject Schoutedenella monophyly, but this hypothesis receives no support from non-parametric bootstrapping or Bayesian posterior probabilities. This phylogeny provides a framework for reconstructing historical biogeography and analyzing the evolution of body size and life history. Direct development and miniaturization appear at the base of Arthroleptis phylogeny concomitant with a range expansion from Central Africa to throughout most of sub-Saharan Africa.     

Modeling nucleotide evolution at the mesoscale: the phylogeny of the neotropical pitvipers of the Porthidium group (viperidae: crotalinae)

We analyzed the phylogeny of the Neotropical pitvipers within the Porthidium group (including intra-specific through inter-generic relationships) using 1.4 kb of DNA sequences from two mitochondrial protein-coding genes (ND4 and cyt-b). We investigated how Bayesian Markov chain Monte-Carlo (MCMC) phylogenetic hypotheses based on this 'mesoscale' dataset were affected by analysis under various complex models of nucleotide evolution that partition models across the dataset. We develop an approach, employing three statistics (Akaike weights, Bayes factors, and relative Bayes factors), for examining the performance of complex models in order to identify the best-fit model for data analysis. Our results suggest that: (1) model choice may have important practical effects on phylogenetic conclusions even for mesoscale datasets, (2) the use of a complex partitioned model did not produce widespread increases or decreases in nodal posterior probability support, and (3) most differences in resolution resulting from model choice were concentrated at deeper nodes. Our phylogenetic estimates of relationships among members of the Porthidium group (genera: Atropoides, Cerrophidion, and Porthidium) resolve the monophyly of the three genera. Bayesian MCMC results suggest that Cerrophidion and Porthidium form a clade that is the sister taxon to Atropoides. In addition to resolving the intra-specific relationships among a majority of Porthidium group taxa, our results highlight phylogeographic patterns across Middle and South America and suggest that each of the three genera may harbor undescribed species diversity.     

A molecular phylogeny of the Sierra-Finches (Phrygilus, Passeriformes): extreme polyphyly in a group of Andean specialists

The unparalleled avian diversity of the Neotropics has long been argued to be in large part the evolutionary consequence of the incredible habitat diversity and rugged topography of the Andes mountains. Various scenarios have been proposed to explain how the Andean context could have generated lineage diversification (e.g. vicariant speciation or parapatric speciation across vertical ecological gradients), yet further study on Andean taxa is needed to reveal the relative importance of the different processes. Here we use mitochondrial and nuclear DNA sequences to derive the first phylogenetic hypothesis for Phrygilus (Sierra-Finches), one of the most species-rich genera of mainly Andean passerines. We find strong evidence that the genus is polyphyletic, comprising four distantly related clades with at least nine other genera interspersed between them (Acanthidops, Catamenia, Diglossa, Haplospiza, Idiopsar, Melanodera, Rowettia, Sicalis and Xenodacnis). These four Phrygilus clades coincide with groups previously established mainly on the basis of plumage characters, suggesting single evolutionary origins for each of these. We consider the history of diversification of each clade, analyzing the timing of splitting events, ancestral reconstruction of altitudinal ranges and current geographical distributions. Phrygilus species origins date mainly to the Pleistocene, with representatives diversifying within, out of, and into the Andes. Finally, we explored whether Phrygilus species, especially those with broad altitudinal and latitudinal Andean distributions, showed phylogeographic structure. Our best-sampled taxon (Phrygilus fruticeti) exhibited no clear pattern; however, we found deep genetic splits within other surveyed species, with Phrygilus unicolor being the most extreme case and deserving of further research.     

A molecular perspective on the phylogeny of the Hyla pulchella species group (Anura, Hylidae)

A molecular phylogenetic analysis of the Hyla pulchella species group was performed to test its monophyly, explore the interrelationships of its species, and evaluate the validity of the taxa that were considered subspecies of H. pulchella. Approximately 2.8 kb from the mitochondrial genes 12s, tRNA valine, 16s, and Cytochrome b were sequenced. The analysis included 50 terminals representing 10 of the 14-15 species currently recognized in the H. pulchella group, including samples from several localities for some taxa, several outgroups, as well as two species previously suspected to be related with the group (Hyla guentheri and Hyla bischoffi). The results show that the H. pulchella and Hyla circumdata groups are distantly related, and, therefore, should be recognized as separate groups. As currently defined, the H. pulchella group is paraphyletic with respect to the Hyla polytaenia group; therefore, we recognize the Hyla polytaenia clade in the H. pulchella group. Two subspecies of H. pulchella recognized by some authors are considered full species including Hyla pulchella riojana because it is only distantly related to H. pulchella, and Hyla pulchella cordobae because molecular and non-molecular evidence suggests that it is specifically distinct. With the inclusion of the H. polytaenia clade, H. guentheri, and H. bischoffi, and the recognition of the two former subspecies of H. pulchella as distinct species, the H. pulchella group now comprises 25 described species. All representatives of the H. pulchella group with an Andean distribution are monophyletic and nested within a clade from the Atlantic forest from south-southeastern Brazil/northeastern Argentina, and Cerrado gallery forest from central Brazil.     

Polyphyly across oceans: a molecular phylogeny of the Chromodorididae (Mollusca, Nudibranchia)

The Chromodorididae is a large and colourful family of nudibranch sea slugs distributed across the world's oceans. Most diversity is centred in the Indo-Pacific, but several genera are present in multiple ocean basins, or across regions separated by biogeographical barriers. The monophyly of these widespread genera had not been tested previously. We used 18S rDNA, 16S rDNA and COI sequence data to generate a molecular phylogeny for this group. We recovered evidence of paraphyly or polyphyly in all of the widespread genera examined ( Hypselodoris , Mexichromis , Chromodoris and Glossodoris ). East Atlantic Hypselodoris and west Atlantic + east Pacific Mexichromis species were more closely related to each other than they were to their Indo-Pacific congeners. The addition of Southern Ocean species of Digidentis demonstrated an interesting alternative to this relationship, becoming the sister group for the east Atlantic Hypselodoris on the basis of 16S and 18S data, but not COI data. Sister group relationships were recovered for most monotypic or enigmatic genera. Ardeadoris is linked to Glossodoris , as is Diversidoris ; Pectenodoris is sister to the Indo-Pacific Mexichromis clade, and Verconia is the sister to Noumea haliclona . Controversy surrounding the placement of the three most basal genera was only partially resolved. Using Actinocyclus to root the mitochondrial trees, Cadlinella was the unsupported sister to the Chromodorididae (excluding Cadlina ), and Tyrinna occupied a relatively basal position, although this also did not receive significant statistical support. Adding nuclear 18S data gave support for Cadlina as the sister group to the rest of the Chromodorididae s.s. Otherwise, like previous molecular studies, mitochondrial genes supported an alternative position for Cadlina (with other dorid genera).     

Reversal to air-driven sound production revealed by a molecular phylogeny of tongueless frogs,family Pipidae

Background

Evolutionary novelties often appear by conferring completely new functions to pre-existing structures or by innovating the mechanism through which a particular function is performed. Sound production plays a central role in the behavior of frogs, which use their calls to delimit territories and attract mates. Therefore, frogs have evolved complex vocal structures capable of producing a wide variety of advertising sounds. It is generally acknowledged that most frogs call by moving an air column from the lungs through the glottis with the remarkable exception of the family Pipidae, whose members share a highly specialized sound production mechanism independent of air movement.

Results

Here, we performed behavioral observations in the poorly known African pipid genus Pseudhymenochirus and document that the sound production in this aquatic frog is almost certainly air-driven. However, morphological comparisons revealed an indisputable pipid nature of Pseudhymenochirus larynx. To place this paradoxical pattern into an evolutionary framework, we reconstructed robust molecular phylogenies of pipids based on complete mitochondrial genomes and nine nuclear protein-coding genes that coincided in placing Pseudhymenochirus nested among other pipids.

Conclusions

We conclude that although Pseudhymenochirus probably has evolved a reversal to the ancestral non-pipid condition of air-driven sound production, the mechanism through which it occurs is an evolutionary innovation based on the derived larynx of pipids. This strengthens the idea that evolutionary solutions to functional problems often emerge based on previous structures, and for this reason, innovations largely depend on possibilities and constraints predefined by the particular history of each lineage.

     

Shark tales: a molecular species-level phylogeny of sharks (Selachimorpha, Chondrichthyes)

Sharks are a diverse and ecologically important group, including some of the ocean's largest predatory animals. Sharks are also commercially important, with many species suffering overexploitation and facing extinction. However, despite a long evolutionary history, commercial, and conservation importance, phylogenetic relationships within the sharks are poorly understood. To date, most studies have either focused on smaller clades within sharks, or sampled taxa sparsely across the group. A more detailed species-level phylogeny will offer further insights into shark taxonomy, provide a tool for comparative analyses, as well as facilitating phylogenetic estimates of conservation priorities. We used four mitochondrial and one nuclear gene to investigate the phylogenetic relationships of 229 species (all eight Orders and 31 families) of sharks, more than quadrupling the number of taxon sampled in any prior study. The resulting Bayesian phylogenetic hypothesis agrees with prior studies on the major relationships of the sharks phylogeny; however, on those relationships that have proven more controversial, it differs in several aspects from the most recent molecular studies. The phylogeny supports the division of sharks into two major groups, the Galeomorphii and Squalimorphii, rejecting the hypnosqualean hypothesis that places batoids within sharks. Within the squalimorphs the orders Hexanchiformes, Squatiniformes, Squaliformes, and Pristiophoriformes are broadly monophyletic, with minor exceptions apparently due to missing data. Similarly, within Galeomorphs, the orders Heterodontiformes, Lamniformes, Carcharhiniformes, and Orectolobiformes are broadly monophyletic, with a couple of species 'misplaced'. In contrast, many of the currently recognized shark families are not monophyletic according to our results. Our phylogeny offers some of the first clarification of the relationships among families of the order Squaliformes, a group that has thus far received relatively little phylogenetic attention. Our results suggest that the genus Echinorhinus is not a squaliform, but rather related to the saw sharks, a hypothesis that might be supported by both groups sharing 'spiny' snouts. In sum, our results offer the most detailed species-level phylogeny of sharks to date and a tool for comparative analyses.     

Multiple hybridization in the Aristolochia kaempferi group (Aristolochiaceae): evidence from reproductive isolation and molecular phylogeny

Hybridization via distributional changes should be an important factor for plant speciation. Previous cpDNA analyses of the Aristolochia kaempferi group, comprising six taxa in East Asia, showed a distinct phylogeographic structure resulting from distributional changes brought about by paleoclimatic oscillations. However, the cpDNA phylogeny was incongruent with morphologically defined taxa. To explore the evolutionary processes responsible for the inconsistency between cpDNA and morphology, we made artificial crosses and performed phylogenetic analyses using multiple nuclear markers. All crosses among different taxa or cpDNA clades set fruit, if crossing direction is not considered. The five nuclear phylogenies mostly did not support either the taxa or the cpDNA clades. A combined analysis of cpDNA and the PI exon revealed the two major lineages in the group, lacking a prezygotic isolating barrier between them. However, an asymmetric prezygotic isolating barrier occurs between populations of the Japanese main islands and of other areas that belong to different cpDNA subclades. It seems reasonable to conclude that the development of a prezygotic isolating mechanism is not necessarily proportional to the degree of genetic divergence. These results suggested that species boundaries within the group are blurred due to speciational processes associated with multiple hybridization and introgression resulting from repeated contacts among differentiated populations.     

A phylogeny of ranid frogs (Anura: Ranoidea: Ranidae), based on a simultaneous analysis of morphological and molecular data

During the last two decades, major taxonomic rearrangements were instituted in the anuran family Ranidae. Most of these changes were not based on phylogenetic analysis, and many are controversial. Addressing the phylogeny of Ranidae requires broader taxon sampling within the superfamily Ranoidea, the phylogenetic relationships and higher classification of which are also in a state of flux. No comprehensive attempt has yet been made to reconstruct ranid phylogeny using both morphological and molecular data. In the present contribution, data from 178 organismal characters were collated for 74 exemplar species representing the families Arthroleptidae, Hemisotidae, Hyperoliidae, Mantellidae Microhylidae, Petropedetidae, Rhacophoridae, Sooglossidae, and most subfamilies of Ranidae. These were combined with ～1 kb of DNA sequence from the mitochondrial 12S rDNA and 16S rDNA gene regions in a simultaneous parsimony analysis with direct optimization. Results support the classification of Hemisus with the brevicipitine microhylids, confirm that Arthroleptidae (and its two component subfamilies Astylosterninae and Arthroleptinae) are monophyletic, and advocate the recognition of Leptopelidae. Monophyly of Ranidae is compromised by recognition of Petropedetidae, Rhacophoridae and Mantellidae, which should be recognized as subfamilies of Ranidae at present. Furthermore, Petropedetidae was found to be grossly paraphyletic, comprising three clades which are all considered separate subfamilies of Ranidae, i.e., Petropedetinae, Phrynobatrachinae and Cacosterninae. Three well defined subfamilies of Ranidae were consistently retrieved as monophyletic in a sensitivity analysis, i.e., Tomopterninae, Ptychadeninae and Pyxicephalinae. However, Ptychadeninae and Pyxicephalinae were embedded in Raninae and Dicroglossinae, respectively. Ceratobatrachinae is removed from Dicroglossinae. Dicroglossinae is synonymized with Pyxicephalinae. A new subfamily Strongylopinae is proposed. Raninae should be conservatively treated as a “metataxon” (sensu Ford and Cannatella, 1993 ) until such time as it is fully revised. Tomopterninae is removed from synonymy with Cacosterninae. Morphological synapomorphies are reported for major monophyletic clades retrieved in the simultaneous analysis with equal weights. The present study found that many Old World clades appear to contain both African and Asian taxa, contrary to the findings of some recent biogeographical analyses. This study demonstrates the value of broad taxonomic sampling in ranid phylogeny, and highlights the immense contribution that can be made from detailed morphological data. © The Willi Hennig Society 2005.