Phylogeny of the genus Merluccius based on mitochondrial and nuclear genes

Genus Merluccius is considered one of the most important groups within the Teleostei, and comprises 12 extant species distributed along the coasts of America, Europe and Africa, being its fisheries very important in these continents. Despite their noticeable economical importance for humans, to date the phylogeny of hakes has not been clearly established. In this study we used mitochondrial sequences (the ribosomal genes 12S rDNA and 16S rDNA, the coding gene cytochrome b and the control region) and the nuclear 5S rDNA conserved region in order to determine the phylogenetic and biogeographical relationships within the genus Merluccius. This is the first time that all the species of this genus recognized by the FAO are included in a phylogeny. Maximum Parsimony, Maximum Likelihood and Bayesian analyses of the mitochondrial sequences suggest that the geographical origin of the genus was the North Atlantic Ocean, and indicate that two main clades, early separated in the evolution, exist within the genus: one American (7 species) and one Euro-African (5 species). Among the American species, M. bilinearis seems to be the most ancient one, and the rise of the Panama Isthmus could act as a physical barrier leading to further processes of speciation. Within the Euro-African clade, successive events of geographical differentiation could explain the observed pattern of species distribution. Therefore, we propose both vicariant speciation and geographical dispersion as main mechanisms to explain the evolutionary history of the genus Merluccius.     

Phylogeny and character evolution of endemic Australian carabid beetles of the genus Pamborus based on mitochondrial and nuclear gene sequences

The phylogeny of carabid beetles in the genus Pamborus (Coleoptera: Carabidae), which is endemic to Australia, was studied using one nuclear (phosphoenolpyruvate carboxykinase) and two mitochondrial (16S ribosomal RNA and NADH dehydrogenase subunit 5) gene sequences, with a cladistic analysis of morphological data. Fourteen species that were morphologically distinguishable were used as ingroup taxa, and Maoripamborus fairburni from New Zealand was assigned as the outgroup. Simultaneous analysis of three gene sequences resulted in well-resolved trees that were largely consistent with the cladogram generated from the morphological data. Based on a clock-like tree calibrated to the New Zealand-Australia/Antarctica split 85 million years ago, it was estimated that extant Pamborus differentiated after the Oligocene, primarily since the mid-Miocene with the onset of a more arid climate and forest fragmentation in Australia. The ancestral Pamborus may have been small, whereas medium to large Pamborus species with exaggerated male genitalia constitute derived groups and are now dominant.     

Phylogeny and taxonomy of the genus Ilyodon Eigenmann, 1907 (Teleostei: Goodeidae), based on mitochondrial and nuclear DNA sequences

Taxonomy of the live‐bearing fish of the genus Ilyodon Eigenmann, 1907 (Goodeidae), in Mexico, is controversial, with morphology and mitochondrial genetic analyses in disagreement about the number of valid species. The present study accumulated a comprehensive DNA sequences dataset of 98 individuals of all Ilyodon species and mitochondrial and nuclear loci to reconstruct the evolutionary history of the genus. Phylogenetic inference produced five clades, one with two sub‐clades, and one clade including three recognized species. Genetic distances in mitochondrial genes (cytb: 0.5%–2.1%; coxI: 0.5%–1.1% and d‐loop: 2.3%–10.2%) were relatively high among main clades, while, as expected, nuclear genes showed low variation (0.0%–0.2%), with geographic concordance and few shared haplotypes among river basins. High genetic structure was observed among clades and within basins. Our genetic analyses, applying the priority principle, suggest the recognition only of Ilyodon whitei and Ilyodon furcidens, with I. cortesae relegated to an invalid species, the populations of which belong to I. whitei.     

Phylogeny of leafcutter ants in the genus Atta Fabricius (Formicidae: Attini) based on mitochondrial and nuclear DNA sequences

Leafcutting ants of the genus Atta are the most conspicuous members of the tribe Attini, the fungus-growing ants. Atta species have long attracted the attention of naturalists, and have since become a common model system for the study of complex insect societies as well as for the study of coevolutionary dynamics due to their numerous interactions with fungi and other microbes. Nevertheless, systematics and taxonomy of the 15 species in the genus Atta have proven challenging, due in part to the extreme levels of worker polymorphism these species display, leading to disagreements about the validity of as many as five different subgenera and calling into question the monophyly of the genus. Here, we use DNA sequence information from fragments of three mitochondrial genes (COI, tRNA leucine and COII) and one nuclear gene (EF1-αF1), totaling 1070 base pairs, to reconstruct the phylogenetic relationships of Atta species using maximum parsimony, maximum likelihood and Bayesian inference techniques. Our results provide support for monophyly of the genus Atta, and suggest that the genus is divided into four monophyletic groups, which correspond to four of the five previously erected Atta subgenera: Atta sensu stricto and Archeatta, each with species composition identical to earlier proposals; Neoatta and Epiatta, with major differences in species composition from earlier proposals. The current geographic ranges of these species suggest that the historical separation of South America from Central and North America has played a role in speciation within this genus.     

Neotomine-peromyscine rodent systematics based on combined analyses of nuclear and mitochondrial DNA sequences

Recently, sequences from two nuclear genes (exon 6 of the dentin matrix protein 1 gene and intron 7 of the beta-fibrinogen gene) and one mitochondrial gene (cytochrome b gene) were used independently in an attempt to resolve phylogenetic relationships within the neotomine-peromyscine complex. Although these studies provided testable hypotheses regarding this group of rodents, the affinities of certain tribes and genera remain uncertain. To elucidate these relationships, the three data partitions were tested for heterogeneity and then concatenated according to conditional data combination and total evidence approaches. Support was found for five clades, four of which correspond to well recognized tribes (the Neotomini, Peromyscini=Reithrodontomyini, Baiomyini, and Tylomyini). Recommendations are made regarding the recognition of Ochrotomys as a tribe of its own, the Ochrotomyini, paralleling other recent findings. The Peromyscini, Baiomyini, and Ochrotomyini are unresolved in relation to each other, but as a whole are sister to the Neotomini. The Tylomyini is basal to all clades. It appears that combined data from the nuclear and mitochondrial genes (analyzing all three partitions simultaneously) resulted in the best phylogenetic hypothesis regarding the complex.     

Phylogenetics and evolution of the aphid genus Uroleucon based on mitochondrial and nuclear DNA sequences

The genus Uroleucon, and the related genus Macrosiphoniella, represent a large Tertiary radiation of aphids, with a total of about 300 species distributed throughout the world, primarily on host plant species in the family Asteraceae. A molecular phylogenetic study was conducted to identify major clades within Uroleucon and to address the cladistic validity of current subgeneric categories, the evolution of host plant associations, the age of origin, and intercontinental movements in this genus. The seventeen study species included members of the three major subgenera of Uroleucon, species from Europe and North America, one member of Macrosiphoniella, and two outgroups. Data consisted of DNA sequences for three mitochondrial regions and the nuclear gene EF1alpha, for a total of 4287 sites. Nodes supported strongly in both parsimony and maximum likelihood analyses suggest that: (1) Nearctic Uromelan are a monophyletic group branching near the base of the genus and not related to European Uromelan, (2) the New World subgenus Lambersius is possibly monophyletic but is not a tightly related group and is not closely related to other North American species, and (3) Nearctic members of subgenus Uroleucon are a closely related monophyletic group not allied with Nearctic Uromelan or Lambersius. Instead they represent a separate colonization by an Old World ancestor, as they are nested within a strongly supported clade containing European members of both subgenera Uroleucon and Uromelan. Neither of these subgenera is monophyletic. Molecular clock calculations, based on calibrations of mitochondrial divergences from other insects, suggest that Uroleucon + Macrosiphoniella is a relatively recent radiation, probably no more than 5–10 million years old. Although largely confined to Asteraceae, this clade did not radiate in parallel with its host plants. Rather, lateral movement between lineages of Asteraceae must have occurred repeatedly.     

Phylogeny of the genus Omphalotus based on nuclear ribosomal DNA-sequences

The evolutionary history of the genus Omphalotus was inferred from DNA sequences of the ITS1-5.8S-ITS2 rDNA region. We analyzed 32 collections from different geographical areas: O. olearius (Europe), O. illudens (Europe, North America), O. subilludens (North America), O. olivascens var. olivascens (North America) and var. indigo (Mexico), O. mexicanus (Middle America), O. nidiformis (Australia), and O. japonicus (Japan). Phylogenetic analysis was performed declaring Nothopanus eugrammus as outgroup. Our analyses show that the genus Omphalotus is split into two major clades, the first consisting of O. illudens and O. mexicanus and the second comprising O. olearius, O. olivascens, O. japonicus, O. nidiformis and O. subilludens. Moreover, the often discussed synonymy of O. illudens and O. olearius is rejected. Omphalotus japonicus, a species formerly placed in the genus Lampteromyces Sing. for morphological reasons, clustered as the sister group of O. olearius.     

Phylogeny of the Drosophila saltans species group based on combined analysis of nuclear and mitochondrial DNA sequences

Nucleotide sequences from two nuclear loci, alcohol dehydrogenase and internal transcribed spacer-1 of the nuclear ribosomal DNA repeats, and two mitochondrial genes, cytochrome oxidase I and cytochrome oxidase II, were determined from nine species in the Drosophila saltans species group. The partition homogeneity test and partitioned Bremer support were used to measure incongruence between phylogenetic hypotheses generated from individual partitions. Individual loci were generally congruent with each other and consistent with the previously proposed morphological hypothesis, although they differed in level of resolution. Since extreme conflict between partitions did not exist, the data were combined and analyzed simultaneously. The total evidence method gave a more resolved and highly supported phylogeny, as indicated by bootstrap proportions and decay indices, than did any of the individual analyses. The cordata and elliptica subgroups, considered to have diverged early in the history of the D. saltans group, were sister taxa to the remainder of the saltans group. The sturtevanti subgroup, represented by D. milleri and D. sturtevanti, occupies an intermediate position in this phylogeny. The saltans and parasaltans subgroups are sister clades and occupy the most recently derived portion of the phylogeny. As with previous morphological studies, phylogenetic relationships within the saltans subgroup were not satisfactorily resolved by the molecular data.      

Phylogeny of Anophelinae (Diptera: Culicidae) based on nuclear ribosomal and mitochondrial DNA sequences

Abstract Phylogenetic relationships among thirty-two species of mosquitoes in subfamily Anophelinae are inferred from portions of the mitochondrial genes COI and COII, the nuclear 18S small subunit rRNA gene and the expansion D2 region of the nuclear large subunit 28S rRNA gene. Sequences were obtained from the genera Anopheles , Bironella and Chagasia . Representatives of all six subgenera of Anopheles were included: Anopheles , Cellia , Kerteszia , Lophopodomyia , Nyssorhynchus and Stethomyia. Using parsimony and maximum likelihood methods, various combinations of these DNA sequence data were analysed separately: 18S, 28S, combined 18S and 28S, combined COI and COII, and combined 18S, 28S, COI and COII ('total evidence'). The combined rDNA data contain strong phylogenetic signal, moderately to strongly supporting most clades in MP and ML analyses; however, the mtDNA data (analysed as either nucleotide or amino acid sequences) contain little phylogenetic signal, except for relationships of very recently derived groups of species and, at the deepest level, for the monophyly of Anophelinae. The paraphyly of Anopheles relative to Bironella is confirmed by most analyses and statistical tests. Support for the monophyly of subgenera Anopheles , Cellia , Kerteszia and Nyssorhynchus is indicated by most analyses. Subgenus Lophopodomyia is reconstructed as the sister to Bironella , nested within a clade also containing Nyssorhynchus and Kerteszia . The most basal relationships within genus Anopheles are not well resolved by any of the data partitions, although the results of statistical analyses of the rDNA data (S-H-tests, likelihood ratio tests for monophyly and Bayesian MCMC analyses) suggest that the clade consisting of Bironella , Lophopodomyia , Nyssorhynchus and Kerteszia is the sister to the clade containing Cellia and Anopheles .     

Phylogenetic relationships of finches and allies based on nuclear and mitochondrial DNA

The complete mitochondrial gene cytochrome b in combination with a nuclear gene, beta-fibrinogen intron 7, is sequenced for different groups of mostly granivorous species in the superfamily Passeroidea, with a focus on the estrildids and fringillids. From our study we can conclude that within the group of granivorous finches two clades can be distinguished, the estrildid weaver clade and the cardueline, fringillid, emberizid, passerine sparrow clade. In contrast to many other studies the passerine sparrows are not placed within the weavers estrildid clade which is in agreement with other recent studies (e.g., ). Our study also shows that the estrildids do form a monophyletic group, but there is a division based on geographic origin: an African group and an Asian-Australian group. Within the Fringillidae the Fringilla species are the sister group of the carduelines.     

A phylogenetic analysis of laughingthrushes (Timaliidae: Garrulax) and allies based on mitochondrial and nuclear DNA sequences

The interspecific relationships among extant laughingthrushes have been unclear for a long time and this has resulted in a confusing taxonomic history. Recent advances in molecular methods have greatly improved the resolution of the phylogeny of birds; however, little works has been done on this specific group because of the inaccessibility to many species. This diverse group includes 50 species mostly distributed in South China and South-east Asia, and were traditionally arranged into the genus Garrulax , for which the non monophyly had been questioned by previous molecular studies. In this study, we infer a phylogeny for 23 Garrulax species and 20 species from close related genera. Mitochondrial data or combined with nuclear sequences both indicate paraphyly of Garrulax , dividing Garrulax species into two groups. Based on these results, we suggest resurrecting the genus name Trochalopteron Blyth, 1843 for one group and retaining Garrulax for the other pending further study. Using dating methods with a secondary calibration point, we develop a profile of the speciation history of laughingthrushes, which suggests that the Hengduan Mountains might not be the centre of origin for these birds as previously suggested.     

Phylogeny of the tree swallow genus, Tachycineta (Aves: Hirundinidae), by Bayesian analysis of mitochondrial DNA sequences

To set the stage for historical analyses of the ecology and behavior of tree swallows and their allies (genus Tachycineta), we reconstructed the phylogeny of the nine Tachycineta species by comparing DNA sequences of six mitochondrial genes: Cytochrome b (990 base pairs), the second subunit of nicotinamide adenine dinucleotide dehydrogenase (839 base pairs), cytochrome oxidase II (85 base pairs), ATPase 8 (158 base pairs), tRNA-lysine (73 base pairs), and tRNA-methionine (25 base pairs). The phylogeny consisted of two main clades: South and Central American species ((T. stolzmanni, T. albilinea, T. albiventris), (T. leucorrhoa, T. meyeni)), and North American and Caribbean species (T. bicolor, (T. thalassina, T. euchrysea, T. cyaneoviridis)). The genetic distances among the species suggested that Tachycineta is a relatively old group compared to other New World swallow genera. One interesting biogeographic discovery was the close relationship between Caribbean and western North American taxa. This historical connection occurs in other groups of swallows and swifts as well. To reconstruct the phylogeny, we employed Bayesian as well as traditional maximum-likelihood methods. The Bayesian approach provided probability values for trees produced from the different genes and gene combinations, as well as probabilities of branches within those trees. We compared Bayesian and maximum-likelihood bootstrap branch support and found that all branches with Bayesian probabilities > or = 95% received bootstrap support >70%.     

Phylogeny of mysticete whales based on mitochondrial and nuclear data

Mysticetes or baleen whales are comprised of four groups: Eschrichtiidae, Neobalaenidae, Balaenidae, and Balaenopteridae. Various phylogenetic hypotheses among these four groups have been proposed. Previous studies have not satisfactorily determined relationships among the four groups with a high degree of confidence. The objective of this study is to determine the relationships among the mysticete whales. Mitochondrial and nuclear DNA were sequenced for phylogenetic analysis. Most species relationships determined using these data were well resolved and congruent. Balaenidae is the most basal group and Neobalaenidae is the second most basal and sister group to the balaenopterid-eschrichtiid clade. In this phylogenetic study, the resolution of Eschrichtiidae with two main lineages of Balaenopteridae was problematic. Some data partitions placed this group within the balaenopterids, and other partitions placed it as a sister taxon to the balaenopterids. An additive likelihood approach was used to determine the most optimal trees. Although it was not found in the combined phylogenetic analyses, the "best" tree found under the additive likelihood approach was one with a monophyletic Balaenopteridae.     

Phylogeny of the subgenus sophophora (Diptera: drosophilidae) based on combined analysis of nuclear and mitochondrial sequences

Sequences from the nuclear (nu) alcohol dehydrogenase gene, the nu 28S ribosomal RNA locus, and the mitochondrial cytochrome oxidase II gene were used both individually and in combined analyses to infer the phylogeny of the subgenus Sophophora (Diptera: Drosophilidae). We used several optimality criteria, including maximum likelihood, maximum parsimony, and minimum evolution, to analyze these partitions to test the monophyly of the subgenus Sophophora and its four largest species groups, melanogaster, obscura, saltans, and willistoni. Our results suggest that the melanogaster and obscura species groups are each monophyletic and form a closely related clade. The Neotropical clade, containing the saltans and willistoni species groups, is also recovered, as previous studies have suggested. While the saltans species group is strongly supported as monophyletic, the results of several analyses indicate that the willistoni species group may be paraphyletic with respect to the saltans species group.     

Supraordinal phylogenetic relationships of Lecanoromycetes based on a Bayesian analysis of combined nuclear and mitochondrial sequences

Phylogenetic relationships of lichen-forming discomycetes and their relatives in the class Lecanoromycetes were examined by using nuclear large subunit and mitochondrial small subunit ribosomal DNA sequences. Ninety-eight partial sequences of 53 ascomycetes were generated and aligned with the corresponding sequences retrieved from GenBank resulting in an alignment of 100 taxa that was analyzed using a Bayesian approach with Markov chain Monte Carlo (B/MCMC) methods. The analysis revealed the monophyly of the Lecanoromycetes with two major clades: one clade including the monophyletic orders Graphidales and Ostropales and the paraphyletic Gyalectales, the other clade including the monophyletic Lecanorales (incl. Caliciales, Peltigerales, and Teloschistales) and a clade containing the polyphyletic Agyriales, a yet undescribed order Umbilicariales (including Elixiaceae and Umbilicariaceae), and Pertusariales. The monophyly of the Pertusariales was not resolved. Testing of alternative hypotheses revealed that a placement of Chaetothyriomycetes and Eurotiomycetes within Lecanoromycetes and the monophyly of Agyriales s. lat. (incl. Elixiaceae and Schaereriaceae) and Ostropales s. lat. (incl. Graphidales) can be rejected, while monophyly of Gyalectales and the Pertusariales and placement of Umbilicariales on the Lecanorales branch cannot be rejected with the current data set.     

Molecular systematics of the damselfishes (Teleostei: Pomacentridae): Bayesian phylogenetic analyses of mitochondrial and nuclear DNA sequences

Damselfishes in the family Pomacentridae represent one of the few families of reef fishes found on coral reefs irrespective of location. At a local scale, damselfishes are often the most abundant coral reef fish, and their study has provided much of our current understanding of the ecology of tropical reef animals. The study of phylogenetic relationships among the Pomacentridae has lagged ecological investigation of the group, thus limiting historical perspective on the remarkable species richness of the family. In this study, we used 1989bp of DNA sequence representing three mitochondrial genes and 1500bp of the single copy nuclear RAG1 region to infer hypotheses of relationship for the group. Our analysis includes 103 Pomacentridae species in 18 genera, and three of the four named subfamilies: Amphriprioninae, Chrominae, and Pomacentrinae. The Bayesian method of phylogenetic reconstruction was applied to the data, because even with a large number of sequences it is an efficient means of analysis that provides intuitive measures of support for tree topologies and for the parameters of the nucleotide substitution model. Four Pomacentridae clades were identified with high statistical support whether the data were analyzed from a mtDNA, RAG1 or combined perspective, and in all analyses the current subfamilial classification of the Pomacentridae was rejected. At the genus level, Amphiprion, Chromis, and Chrysiptera were also rejected as natural groups. Abudefduf, Amblyglyphidodon, Dascyllus, Neoglyphidodon, Neopomacentrus, and Pomacentrus were each strongly supported as monophyletic genera but the support for monophyly is nonetheless compromised by sample size, except in the case of Dascyllus and Abudefduf for which we have sampled almost all of the described species.     

Phylogeny of the bears (Ursidae) based on nuclear and mitochondrial genes

The taxomic classification and phylogenetic relationships within the bear family remain argumentative subjects in recent years. Prior investigation has been concentrated on the application of different mitochondrial (mt) sequence data, herein we employ two nuclear single-copy gene segments, the partial exon 1 from gene encoding interphotoreceptor retinoid binding protein (IRBP) and the complete intron 1 from transthyretin (TTR) gene, in conjunction with previously published mt data, to clarify these enigmatic problems. The combined analyses of nuclear IRBP and TTR datasets not only corroborated prior hypotheses, positioning the spectacled bear most basally and grouping the brown and polar bear together but also provided new insights into the bear phylogeny, suggesting the sister-taxa association of sloth bear and sun bear with strong support. Analyses based on combination of nuclear and mt genes differed from nuclear analysis in recognizing the sloth bears as the earliest diverging species among the subfamily ursine representatives while the exact placement of the sun bear did not resolved. Asiatic and American black bears clustered as sister group in all analyses with moderate levels of bootstrap support and high posterior probabilities. Comparisons between the nuclear and mtDNA findings suggested that our combined nuclear dataset have the resolving power comparable to mtDNA dataset for the phylogenetic interpretation of the bear family. As can be seen from present study, the unanimous phylogeny for this recently derived family was still not produced and additional independent genetic markers were in need.     

Phylogeny of the leech family Glossiphoniidae based on mitochondrial gene sequences and morphological data

The phylogenetic relationships of the Glossiphoniidae (Rhynchobdellida) were investigated using morphological characters and the mitochondrial genes cytochrome c oxidase subunit I and nicotinamide adenine dinucleotide dehydrogenase subunit 1. Thirty-five taxa representing 10 of the 23 currently recognized glossiphoniid genera were sampled, including more than 70% of known North American species, as well as others from Europe, South America, Africa, and a species endemic to Lake Baikal. Outgroup taxa included species from the Piscicolidae and Ozobranchidae. Cladistic analysis resulted in 1 most-parsimonious tree. Subfamily distinctions, i.e., Haementeriinae, Theromyzinae, and Glossiphoniinae, that have been based on eye morphology and reproductive biology are not corroborated. Results also provide insights into several problematic genus-level classifications. For example, relationships of Placobdella and Haementeria are clarified and elimination of Desserobdella may be necessary. Bloodfeeding from vertebrates is seen to be a primitive characteristic that has been lost twice within the clade. The hypothesis that the biannulate leech, Oligobdella biannulata, represents an important transitional form is re-evaluated in a phylogenetic context.     

Phylogeny and genetic diversity of Bridgeoporus nobilissimus inferred using mitochondrial and nuclear rDNA sequences

The genetic diversity and phylogeny of Bridgeoporus nobilissimus have been analyzed. DNA was extracted from spores collected from individual fruiting bodies representing six geographically distinct populations in Oregon and Washington. Spore samples collected contained low levels of bacteria, yeast and a filamentous fungal species. Using taxon-specific PCR primers, it was possible to discriminate among rDNA from bacteria, yeast, a filamentous associate and B. nobilissimus. Nuclear rDNA internal transcribed spacer (ITS) region sequences of B. nobilissimus were compared among individuals representing six populations and were found to have less than 2% variation. These sequences also were used to design dual and nested PCR primers for B. nobilissimus-specific amplification. Mitochondrial small-subunit rDNA sequences were used in a phylogenetic analysis that placed B. nobilissimus in the hymenochaetoid clade, where it was associated with Oxyporus and Schizopora.