Mitogenomic evidence for the monophyly of elopomorph fishes (Teleostei) and the evolutionary origin of the leptocephalus larva

The monophyly of Elopomorpha (eels and their relatives) has long been one of the most problematic issues in systematic ichthyology. Since established the Elopomorpha based on the existence of the leaf-like larval form, termed a leptocephalus, no one has corroborated their monophyly using character matrices derived from both morphological and molecular data during the last 30 years. We investigated their monophyly and interrelationships at the ordinal level using complete mitochondrial genomic (mitogenomic) data from 33 purposefully chosen species (data for nine species being newly determined during the study) that fully represent the major teleostean and elopomorph lineages. Partitioned Bayesian analyses were conducted with the two data sets that comprised concatenated nucleotide sequences from 12 protein-coding genes (with and without third codon positions), 22 transfer RNA genes, and two ribosomal RNA genes. The resultant trees were well resolved and largely congruent, with most internal branches being supported by high statistical values. Mitogenomic data strongly supported the monophyly of Elopomorpha, indicating the validity of the leptocephalus as an elopomorph synapomorphy. The order Elopiformes occupied the most basal position in the elopomorph phylogeny, with the Albuliformes and a clade comprising the Anguilliformes and the Saccopharyngiformes forming a sister group. The most parsimonious reconstruction of the three previously recognized, distinct larval types of elopomorphs onto the molecular phylogeny revealed that one of the types (fork-tailed type) had originated as the common ancestor of the Elopomorpha, the other two (filament-tailed and round-tailed types) having diversified separately in two more derived major clades.     

Phylogenetic footprints of an Antarctic radiation: The Trematominae (Notothenioidei, Teleostei)

The teleost suborder Notothenioidei is restricted to the Southern Ocean and has been described as a species flock spanning the whole of it. Within the suborder, the subfamily Trematominae is important for coastal Antarctic ecosystems. The eleven Trematomus species occupy a large range of ecological niches. The genus is monophyletic if the genus Pagothenia (two additional species) and Cryothenia amphitreta, also nested within it, are included. Although the Trematominae have received much interest, the relationships among these fourteen species are still unclear. Several recent studies have tried to resolve these interrelationships; however no complete and clear picture has emerged, probably because of the use of a low number of insufficiently variable markers. The only common results places T. scotti as the sister-group of the rest of the subfamily and T. loennbergi close to T. lepidorhinus. We use here more variable markers. Four nuclear markers, two of which are new, and a mitochondrial marker for the biggest trematomine sampling ever gathered (14 species, 78 specimens). We found that several nuclear haplotypes are shared by several species (mostly in very closely related species). The haplotype patterns coupled with the cytogenetics of the subfamily suggest that a phenomenon of incomplete lineage sorting (ILS) is likely to be at play. Using a calibration linked to fossil evidence, we evaluate the relative ages of each clade within the Trematominae to assess the proximity of the speciation events to one another. The main trematomine diversification was recent and sudden.     

Molecular evolution of hemoglobins of antarctic fishes (Notothenioidei)

Amino acid sequences of α- and β-chains of human hemoglobin and of hemoglobins of coelacanth and 24 teleost fish species, including 11 antarctic and two temperate Notothenioidei, were analyzed using maximum parsimony. Trees were derived for the α- and β-chains separately and for tandemly arranged sequences, using the human and coelacanth sequences as outgroups in all analyses. The topologies of the trees of the α-and β-chains are highly congruent and indicate a specific pattern of gene duplications and gene expression of teleost hemoglobins which has not yet been investigated into more detail. The Notothenioid fish generally contain a single major hemoglobin and often a second minor component. The α- and β-chains of the major components form a monophyletic group in all investigated trees, with the nonantarctic Pseudaphritis as their sister taxon. The minor chains also are a monophyletic group and form an unresolved cluster with the major chains and the hemoglobins of tuna and red gurnard. The Notothenioid families Nototheniidae and Bathydraconidae appear to be paraphyletic. Received: 26 March 1997 / Accepted: 7 May 1997     

The Antarctic fish genus Artedidraco is paraphyletic (Teleostei, Notothenioidei, Artedidraconidae)

Artedidraconids (Plunderfishes) are small benthic notothenioid fishes of the Antarctic and South Georgia shelf and slope. The family Artedidraconidae is monophyletic; however, the relationships within the family have remained poorly explored until now, and based on a small sample of the genus Artedidraco. The present study focuses on the interrelationships among the artedidraconid genera and the phylogeny of the genus Artedidraco. 2,353 base pairs from 77 specimens were sequenced from the partial mitochondrial cytochrome oxidase I gene and cytochrome b gene, the partial mitochondrial control region and the partial nuclear rhodopsin retrogene. The genus Artedidraco is not monophyletic, confirming the preliminary relationships found by Derome et al. (Mol Phylogenet Evol 24:139–152, 2002): Pogonophryne, Dolloidraco and Histiodraco are well embedded within the genus Artedidraco. From Artedidraco skottsbergi and A. loennbergi to A. orianae and A. mirus, the tree shows that there is an increasing number of upper lateral line tubular scales and decreasing number of disc-shaped scales. There is also a trend toward a decrease in the number of epipleural ribs and an increase in number of pleural ribs along the tree.     

Analysis of dietary overlap in Antarctic fish (Notothenioidei) from the South Shetland Islands: no evidence of food competition

A dietary overlap analysis between notothenioid species was carried out among three fish assemblages in the South Shetland Island area. Using Tyler's (1972) method, the re-occurrence of main and secondary prey among fish predators was 33% in summer and 37% over the year at Potter Cove, 25% in summer and 7% in winter at Admiralty Bay, and 20% in autumn/winter around Elephant Island. Likewise, using the "S" index of Linton et al. (1981), the diet similarity between most species pairs is <50%. This relatively low dietary overlap may be explained by the about equally divided occurrence of generalised feeders and specialised feeders, with no evidence of competition among them. The fishes' trophic niches seem to be separated by depth and prey taxa. These findings are compared with other Antarctic fish communities and those in similar non-Antarctic cold marine ecosystems.     

The monophyly of the Characidiinae, a Neotropical group of characiform fishes (Teleostei: Ostariophysi)

Although virtually no phylogenetic evidence (in the sense advocated by Hennig, 1966) had been previously presented to support the monophyly of the Characidiinae, and most 'diagnostic' characters used by previous authors were found to be unacceptable in a cladistic classification, i t is still possible to diagnose the Characidiinae in a phylogenetic sense. This study revealed the existence of 13 synapomorphies supporting the monophyly of the group. Several of these synapomorphies, such as the modifications associated with the mesethmoid, the jaw bones, and the ribs of the fifth vertebra, are unique to the Characidiinae, thus providing a solid basis for recognizing the group as a monophyletic unit of characiform fishes. Demonstration of characidiin monophyly provides a solid foundation for further phylogenetic analysis of characidiin interrelationships, and higher level relationships among characiform fishes.     

Brain and sense organ anatomy and histology of two species of phyletically basal non-Antarctic thornfishes of the Antarctic suborder Notothenioidei (Perciformes: Bovichtidae)

The predominantly non-Antarctic family Bovichtidae is phyletically basal within the perciform suborder Notothenioidei, the dominant component of the Antarctic fish fauna. In this article we focus on the South Atlantic bovichtids Bovichtus diacanthus, the klipfish from tide pools at Tristan da Cunha, and Cottoperca gobio, the frogmouth from the Patagonian shelf and Falkland Islands. We document the anatomy and histology of the brains, olfactory apparatus, retina, and cephalic lateral line system. We also use the microvascular casting agent Microfil to examine ocular vascular structures. We provide detailed drawings of the brains and cranial nerves of both species. Typical of perciforms, the brains of both species have a well-developed tectum and telencephalon and robust thalamic nuclei. The telencephalon of C. gobio is prominently lobed, with the dorsomedial nucleus more conspicuous than in any other notothenioid. The corpus cerebelli is relatively small and upright and, unlike other notothenioids, has prominent transverse sulci on the dorsal and caudal surfaces. Areas for lateral line mechanoreception (eminentia granularis and crista cerebellaris) are also conspicuous but olfactory, gustatory, and somatosensory areas are less prominent. The anterior lateral line nerve complex is larger than the posterior lateral line nerve in B. diacanthus, and in their cephalic lateral line systems both species possess branched membranous tubules (which do not contain neuromasts) with small pores. These are especially complex in B. diacanthus where they become increasingly branched and more highly pored in progressively larger specimens. Superficial neuromasts are sparse. Both species have duplex (cone and rod) retinae that are 1.25-fold thicker and have nearly 5-fold more photoreceptors and than those of most Antarctic notothenioids. Convergence ratios are also high for bovichtids. Bovichtus diacanthus has a yellow intraocular filter in the dorsal aspect of the cornea. Both species are unique among notothenioids in possessing all three vascular structures present in the generalized teleostean eye: the choroid rete mirabile, the lentiform body (also a rete), and the falciform process. When comparing the phyletically derived Antarctic clade exemplified by the families Artedidraconidae, Bathydraconidae, and Channichthyidae to the phyletically basal bovichtids, we observe phyletic regression and reduction in some regions of the brain and in some sensory modalities that are well displayed in bovichtids. In the phyletically derived families the brain is less cellular and nuclei are smaller and less prominent. In some species reduction in the size of the telencephalon, tectum, and corpus cerebelli imparts a "stalked" appearance to the brain with the neural axis visible between the reduced lobes. There is also a phyletic reduction in the number of ocular vascular structures from three in bovichtids to one or none in artedidraconids, bathydraconids, and channichthyids. There are no morphological features of bovichtid brains and sense organs that presage the divergence of the phyletically derived members of the clade in the Antarctic marine environment with its cold and deep continental shelves. We conclude that this environment does not require sensory or neural morphology or capabilities beyond those provided by the basic perciform body plan.     

Aspects of the morphology of phyletically basal bovichtid fishes of the Antarctic suborder Notothenioidei (Perciformes)

In studying the soft tissue anatomy and histology of notothenioids, especially the bovichtids Bovichtus diacanthus and Cottoperca gobio, I evaluated the structure and phyletic distribution of two characters identified by Balushkin (2000) and a new ocular character complex first recognized here. Histology indicates that Balushkin’s antesupracleithral organ is the thymus, a lymphoid organ that involutes with age in notothenioids. Given the universal phyletic distribution of the thymus in gnathostomes, the variation introduced by ontogenetic regression, and its predilection to preservation artifacts, neither its presence nor the appearance of its epidermis are reliable systematic characters in notothenioids. Balushkin’s hypoglossal gland, found in Bovichtus and Cottoperca, is a projection of the mucosa of the oral cavity lateral to the tongue. Histology reveals that it is not a multicellular gland and that its composition does not differ from that of the oral musosa in general—stratified squamous epithelium containing unicellular mucous glands and a few taste buds. While an elaboration of a mucosal fold present in some other notothenioids, the hypoglossal gland is nevertheless sufficiently different and distinct in Bovichtus and Cottoperca that it is a valid synapomorphy for bovichtids. Study of ocular vascular morphology reveals that bovichtids, but not other notothenioids, have a persistent choroid fissure and a low falciform process with a “Dreiecke” (triangle of Virchow). A lentiform body is also present in these two genera but is seen in Pseudaphritis urvillii and Eleginops maclovinus as well. A choroid fissure, falciform process and lentiform body have not been previously noted in notothenioids. The ocular character complex reinforces the phyletically basal position of bovichtids since a choroid fissure and falciform process are widely distributed among perciform outgroups but lost in non-bovichtid notothenioids. Non-traditional morphological characters provide useful information, but preservation can be problematic and museum specimens may not suffice when the structures are truly soft tissue such as the thymus and interior of the eye.     

Muscle metabolism and growth in Antarctic fishes (suborder Notothenioidei): evolution in a cold environment

The radiation of notothenioid fishes (order Perciformes) in the Southern Ocean provides a model system for investigating evolution and adaptation to a low temperature environment. The Notothenioid fishes comprising eight families, 43 genera and 122 species dominate the fish fauna in Antarctica. The diversification of the clade probably began 15–20 million years ago after the formation of the Antarctic Polar Front. The radiation was, therefore, associated with climatic cooling down to the present day temperature of −1.86 °C. Origins and Evolution of the Antarctic Biota Geological Society Special Publication No. 47, Geological Society of London. pp. 253–268). The success of the group has been closely linked with the evolution of glycopeptide and peptide antifreezes, which are amongst the most abundant proteins in blood and interstitial fluid. The radiation of the clade has been associated with disaptation (evolutionary loss of function) and recovery. For example, it is thought that the icefishes (Channichyidae) lost haemoglobin through a single mutational event leading to the deletion of the entire β-globin gene and the 5′ end of the linked α-globin gene, resulting in compensatory adaptations of the cardiovascular system. Phylogenetically based statistical methods also indicate a progressive and dramatic reduction in the number of skeletal muscle fibres (FN_max) at the end of the recruitment phase of growth in basal compared to derived families. The reduction in FN_max is associated with a compensatory increase in the maximum fibre diameter, which can reach 100 μm in slow and 600 μm in fast muscle fibres. At −1 to 0 °C, the oxygen consumption of isolated mitochondria per mg mitochondrial protein shows no evidence of up-regulation relative to mitochondria from temperate and tropical Perciform fishes. The mitochondria content of slow muscle fibres in Antarctic notothenioids is towards the upper end of the range reported for teleosts with similar lifestyles, reaching 50% in Channichthyids. High mitochondrial densities facilitate ATP production and oxygen diffusion through the membrane lipid compartment of the fibre. Modelling studies suggest that adequate oxygen flux in the large diameter muscle fibres of notothenioids is possible because of the reduced metabolic demand and enhanced solubility of oxygen associated with low temperature. At the whole animal level size-corrected resting metabolic rate fits on the same temperature relationship as for Perciformes from warmer climates. It seems likely that the additional energetic costs associated with antifreeze synthesis and high mitochondrial densities are compensated for by reductions in other energy requiring processes: a hypothesis that could be tested with detailed energy budget studies. One plausible candidate is a reduction in membrane leak pathways linked to the loss of muscle fibres, which would serve to minimise the cost of maintaining ionic gradients.     

Molecular phylogeny of the gobioid fishes (Teleostei: Perciformes: Gobioidei)

The phylogeny of groups within Gobioidei is examined with molecular sequence data. Gobioidei is a speciose, morphologically diverse group of teleost fishes, most of which are small, benthic, and marine. Efforts to hypothesize relationships among the gobioid groups have been hampered by the prevalence of reductive evolution among goby species; such reduction can make identification of informative morphological characters particularly difficult. Gobies have been variously grouped into two to nine families, several with included subfamilies, but most existing taxonomies are not phylogenetic and few cladistic hypotheses of relationships among goby groups have been advanced. In this study, representatives of eight of the nine gobioid familes (Eleotridae, Odontobutidae, Xenisthmidae, Gobiidae, Kraemeriidae, Schindleriidae, Microdesmidae, and Ptereleotridae), selected to sample broadly from the range of goby diversity, were examined. Complete sequence from the mitochondrial ND1, ND2, and COI genes (3573 bp) was used in a cladistic parsimony analysis to hypothesize relationships among the gobioid groups. A single most parsimonious topology was obtained, with decay indices indicating strong support for most nodes. Major phylogenetic conclusions include that Xenisthmidae is part of Eleotridae, and Eleotridae is paraphyletic with respect to a clade composed of Gobiidae, Microdesmidae, Ptereleotridae, Kraemeriidae, and Schindleriidae. Within this five-family clade, two clades are recovered. One includes Gobionellinae, which is paraphyletic with respect to Kraemeriidae, Sicydiinae, Oxudercinae, and Amblyopinae. The other contains Gobiinae, also paraphyletic, and including Microdesmidae, Ptereleotridae, and Schindleriidae. Previous morphological evidence for goby groupings is discussed; the phylogenetic hypothesis indicates that the morphological reduction observed in many goby species has been derived several times independently.     

Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplasy

Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cytb, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu (Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira–Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works.     

Molecular evidence for the monophyly of East Asian groups of Cyprinidae (Teleostei: Cypriniformes) derived from the nuclear recombination activating gene 2 sequences

The family Cyprinidae is one of the largest families of fishes in the world and a well-known component of the East Asian freshwater fish fauna. However, the phylogenetic relationships among cyprinids are still poorly understood despite much effort paid on the cyprinid molecular phylogenetics. Original nucleotide sequence data of the nuclear recombination activating gene 2 were collected from 109 cyprinid species and four non-cyprinid cypriniform outgroup taxa and used to infer the cyprinid phylogenetic relationships and to estimate node divergence times. Phylogenetic reconstructions using maximum parsimony, maximum likelihood, and Bayesian analysis retrieved the same clades, only branching order within these clades varied slightly between trees. Although the morphological diversity is remarkable, the endemic cyprinid taxa in East Asia emerged as a monophyletic clade referred to as Xenocypridini. The monophyly for the subfamilies including Cyprininae and Leuciscinae, as well as the tribes including Labeonini, Gobionini, Acheilognathini, and Leuciscini, was also well resolved with high nodal support. Analysis of the RAG2 gene supported the following cyprinid molecular phylogeny: the Danioninae is the most basal subfamily within the family Cyprinidae and the Cyprininae is the sister group of the Leuciscinae. The divergence times were estimated for the nodes corresponding to the principal clades within the Cyprinidae. The family Cyprinidae appears to have originated in the mid-Eocene in Asia, with the cladogenic event of the key basal group Danioninae occurring in the early Oligocene (about 31-30 MYA), and the origins of the two subfamilies, Cyprininae and Leuciscinae, occurring in the mid-Oligocene (around 26 MYA).     

Morphological evidence supporting the monophyly of the family Polynemidae (Teleostei: Perciformes) and its sister relationship with Sciaenidae

The monophyly of Polynemidae was evaluated and its sister relationship with Sciaenidae discussed, based on osteological and myological characters from 24 polynemid species in eight genera, with comparisons with acanthomorph fishes from literature and 86 species in 8 orders and 63 families examined. Polynemidae was inferred as a monophyletic group, strongly supported by 19 synapomorphies, including four unique characters (unnamed bone present on cephalic sensory canal extending from supratemporal, third actinost not supporting pectoral-fin rays, section A1 comprising lateral and medial elements, and division of obliquus inferioris present between lower postcleithrum and rod-like process on coracoid) in percoids. In addition, seven pectoral girdle characters were recognized, with the girdle possessing filament-like sensory rays, an adaptation to benthic life in muddy water. The sister relationship of Polynemidae and Sciaenidae was supported by six synapomorphies, including two rather rare (a single branchiostegal ray suspended by epihyal and posterior portions of pelvic bones on both sides interdigitated) and two unique characters (metapterygoid and quadrate interdigitated medially and anterior extension of the nasal canal).     

Multilocus analyses of an Antarctic fish species flock (Teleostei, Notothenioidei, Trematominae): phylogenetic approach and test of the early-radiation event

Clades that have undergone episodes of rapid cladogenesis are challenging from a phylogenetic point of view. They are generally characterised by short or missing internal branches in phylogenetic trees and by conflicting topologies among individual gene trees. This may be the case of the subfamily Trematominae, a group of marine teleosts of coastal Antarctic waters, which is considered to have passed through a period of rapid diversification. Despite much phylogenetic attention, the relationships among Trematominae species remain unclear. In contrast to previous studies that were mostly based on concatenated datasets of mitochondrial and/or single nuclear loci, we applied various single-locus and multilocus phylogenetic approaches to sequences from 11 loci (eight nuclear) and we also used several methods to assess the hypothesis of a radiation event in Trematominae evolution. Diversification rate analyses support the hypothesis of a period of rapid diversification during Trematominae history and only a few nodes in the hypothetical species tree were consistently resolved with various phylogenetic methods. We detected significant discrepancies among trees from individual genes of these species, most probably resulting from incomplete lineage sorting, suggesting that concatenation of loci is not the most appropriate way to investigate Trematominae species interrelationships. These data also provide information about the possible effects of historic climate changes on the diversification rate of this group of fish.     

Phylogenetic investigations of Antarctic notothenioid fishes (Perciformes: Notothenioidei) using complete gene sequences of the mitochondrial encoded 16S rRNA

The Notothenioidei dominates the fish fauna of the Antarctic in both biomass and diversity. This clade exhibits adaptations related to metabolic function and freezing avoidance in the subzero Antarctic waters, and is characterized by a high degree of morphological and ecological diversity. Investigating the macroevolutionary processes that may have contributed to the radiation of notothenioid fishes requires a well-resolved phylogenetic hypothesis. To date published molecular and morphological hypotheses of notothenioids are largely congruent, however, there are some areas of significant disagreement regarding higher-level relationships. Also, there are critical areas of the notothenioid phylogeny that are unresolved in both molecular and morphological phylogenetic analyses. Previous molecular phylogenetic analyses of notothenioids using partial mtDNA 12S and 16S rRNA sequence data have resulted in limited phylogenetic resolution and relatively low node support. One particularly controversial result from these analyses is the paraphyly of the Nototheniidae, the most diverse family in the Notothenioidei. It is unclear if the phylogenetic results from the 12S and 16S partial gene sequence dataset are due to limited character sampling, or if they reflect patterns of evolutionary diversification in notothenioids. We sequenced the complete mtDNA 16S rRNA gene for 43 notothenioid species, the largest sampling to-date from all eight taxonomically recognized families. Phylogenetic analyses using both maximum parsimony and maximum likelihood resulted in well-resolved trees with most nodes supported with high bootstrap pseudoreplicate scores and significant Bayesian posterior probabilities. In all analyses the Nototheniidae was monophyletic. Shimodaira–Hasegawa tests were able to reject two hypotheses that resulted from prior morphological analyses. However, despite substantial resolution and node support in the 16S rRNA trees, several phylogenetic hypotheses among closely related species and clades were not rejected. The inability to reject particular hypotheses among species in apical clades is likely due to the lower rate of nucleotide substitution in mtDNA rRNA genes relative to protein coding regions. Nevertheless, with the most extensive notothenioid taxon sampling to date, and the much greater phylogenetic resolution offered by the complete 16S rRNA sequences over the commonly used partial 12S and 16S gene dataset, it would be advantageous for future molecular investigations of notothenioid phylogenetics to utilize at the minimum the complete gene 16S rRNA dataset.     

Interrelationships of the ostariophysan fishes (Teleostei)

The history of ostariophysan classification is summarized and it is noted that traditional concepts of relationships have never been supported by characters found to be unique to the taxa. We present a new hypothesis of relationships among four of the five major ostariophysan lineages: Cypriniformes, Characiformes, Siluroidei, and Gymnotoidei (Otophysi). Cypriniforms are the sister-group of the remaining three (Characiphysi), and characiforms are the sister-group of siluroids plus gymnotoids (Siluriformes). Placement of the Gonorynchiformes as the sister-group of the Otophysi is supported by additional evidence. Each of the five lineages is monophyletic. Analysis was concentrated upon species thought to be the least specialized within each lineage; choices of these species are discussed. Chanos is determined to be a relatively primitive gonorynchiform morphologically and the sister-group of all other Recent members of the order. Opsariichthys and Zacco are found to be morphologically primitive cypriniforms. We propose that a monophyletic group comprising the Citharinidae and Distichodontidae forms the sister-group of all other characiforms. Within the two families, Xenocharax is the least specialized. We suggest that Hepsetus, the erythrinids, and the ctenoluciids are more derived than the distichodontids and citharinids, and may form a monophyletic group within die characiforms. The traditional hypothesis that Diplomystes is the primitive sister-group of all Recent siluroids is substantiated. Our evidence suggests that Sternopygus is the most primitive gymnotoid morphologically; but rather than being the sister-group of all other gymnotoids, it is the primitive sister-group within a lineage called the Sternopygidae by Mago-Leccia. Previous explanations of otophysan distribution have been based on notions of relationships which are unsupported by the evidence presented herein. Our own analysis of relationships serves primarily to make clear the extent of sympatry, and therefore the probability of dispersal, among the major ostariophysan lineages. The extent of sympatry, together with the widespread distribution of ostariophysans, suggests that the group is older than previously supposed, and our hypotheses of relationships among the characiforms implies that many of the extent characiform lineages evolved before the separation of Africa and South America. Further understanding of ostariophysan distribution must await phylogenetic analysis within each of the five major lineages so that distributions linked with vicariance patterns and dispersal events can be sorted out.     

Polyphyly of the mail-cheeked fishes (Teleostei: Scorpaeniformes): evidence from mitochondrial and nuclear sequence data

Mitochondrial and nuclear DNA sequence data for 105 acanthomorph taxa are analyzed to address questions of scorpaeniform monophyly and relationships. The combination of 3425 aligned base pairs from the mitochondrial small subunit rDNA (12S), large subunit rDNA (16S), and tRNA-Val and the nuclear large subunit rDNA (28S), histone H3, and TMO-4c4 loci are analyzed. Representatives of all scorpaeniform suborders and 32 of 36 scorpaeniform families are included with most suborders represented by multiple species. In addition to 69 scorpaeniform taxa, 36 outgroup taxa, including representatives of most families previously conjectured to be related to the Scorpaeniformes, are analyzed due to serious concerns of scorpaeniform monophyly. The traditionally recognized scorpaeniform fishes are recovered as polyphyletic. The 13 representatives of the Atheriniformes, Blennioidei, Gasterosteoidei, Grammatidae, Notothenioidei, Percidae, Trichodontidae, and Zoarcoidei included in the analysis are all nested within the least inclusive clade that includes all traditionally recognized scorpaeniforms. The scorpaenoid lineage is widely polyphyletic, and its intrarelationships differed significantly from previous hypotheses. The cottoid lineage is paraphyletic with only the presence of the Trichodontidae, as the sister-taxon of the Cottoidei, disrupting the traditional subordinal hypothesis of relationships.     

Molecular phylogeny of the fishes traditionally referred to Cyprinini sensu stricto (Teleostei: Cypriniformes)

Yang, L., Mayden, R. L., Sado, T., He, S., Saitoh, K. & Miya, M. (2010). Molecular phylogeny of the fishes traditionally referred to Cyprinini sensu stricto (Teleostei: Cypriniformes). —Zoologica Scripta, 39, 527–550. Carps (e.g. Koi) of the genus Cyprinus and Crucian carps (e.g. Goldfish) of the genus Carassius are among the most popular freshwater fishes around the world. However, their phylogenetic positions within the subfamily Cyprininae, relationships with their allies (e.g. Procypris, Carassioides), and the monophyly of the group formed by them and their allies, which is referred as the tribe Cyprinini sensu stricto, are far from clear. Historically, the Cyprinini was defined by different people according to whether a cyprinine fish possessed a spinous anal‐fin ray (or anal spine), the spine was serrated or not, and occasionally, the number of branched dorsal‐fin rays. Some definitions were established without providing any diagnostic characters. In this study, we investigated the monophyly of the tribe Cyprinini sensu stricto, based on four different historical definitions, and explored the phylogenetic relationships of these members in the subfamily Cyprininae. Using five mitochondrial genes as markers, both maximum‐likelihood and Bayesian trees were constructed using the optimal partitioning strategy. Both analyses successfully resolved a monophyletic Cyprininae and recovered seven major clades from this subfamily. The diagnosis limiting the tribe Cyprinini sensu stricto to four genera, Cyprinus, Carassius, Carassioides and Procypris, received most support. We propose that only those cyprinines that possess a serrated anal spine and have no <10 branched dorsal‐fin rays should be considered members of this tribe. Cyprinini is sister to the Sinocyclocheilus clade, a group traditionally considered a barbin, and together they form the ‘Cyprinini‐Sinocyclocheilus’ clade. Procypris forms the basal clade of the Cyprinini, whereas species of Carassius and Carassioides locate at the top.     

低拷贝核基因序列支持桦木科铁木属为单系鹅耳枥属为并系

Coryloideae consists offour generaCorylus,Ostryopsis,Carpinus,and Ostrya.While both molecular and non-molecular data support the close relationship of Carpinus and Ostrya,the monophyly of the two genera has remained controversial.In this study,sequences of the nuclear nitrate reductase(Nia)were used to test the naturalness of the two genera.Ostrya species form a robust clade,supporting the monophyly of the genus.The clade,however,is located between Carpinus cordata and the remaining species of Carpinus,indicating that Carpinus iS paraphyletic.and Ostrya has evolved from witllin Carpinus.Within Carpinus,section Distegocarpus is polyphyletic,whereas section Carpinus is a clade where subsections Polyneurae and Carpinus are more closely related to each other than either is to subsection Monbeigianae.     

Phylogeny of Antarctic dragonfishes (Bathydraconidae,Notothenioidei, Teleostei) and related families based on their anatomy and two mitochondrial genes

Although Antarctic teleosts of the suborder Notothenioidei are well studied, the status of some families remains unclear because of limited taxonomic sampling and sometimes poor statistical support from molecular phylogenies. It is true for the Bathydraconidae, the sister-family of the famous haemoglobin-less icefishes, the Channichthyidae. The present study is aimed at clarifying bathydraconid phylogeny and the interrelationships of higher notothenioid families, taking nototheniids as the outgroup. For this purpose, about 300 positions in the mitochondrial control region, 750 positions in the cytochrome b, and a matrix of morphological characters were employed for separate and simultaneous phylogenetic analyses. We conclude that (1) molecular data strongly support the split of bathydraconids into three clades, here called the Bathydraconinae (Bathydraco, Prionodraco, Racovitzia), the Gymnodraconinae (Gymnodraco, Psilodraco, Acanthodraco), and the Cygnodraconinae (Cygnodraco, Gerlachea, Parachaenichthys). Interrelationships between these three and the Channichthyidae remain unclear. Molecular data support neither paraphyly nor monophyly of the bathydraconids, while morphology leads to the monophyly of the family based on the synapomorphic loss of the spinous dorsal fin; (2) The Channichthyidae, the Harpagiferidae, and the Artedidraconidae are monophyletic families; (3) the phylogeny of the haemoglobin-less channichthyids is completely resolved and congruent with the conclusions of based on anatomical characters; (4) The present molecular results as well as other molecular studies favour the hypothesis that harpagiferids are the sister-group of artedidraconids, though our morphological matrix puts harpagiferids as the sister-group of all other families on the basis of a single character. With regard to harpagiferid relationships, it is interesting to notice that, when analysed simultaneously, morphological characters are not automatically "swamped" within molecular ones: in the tree based on the simultaneous analysis of all available data, morphological characters impose their topology on molecules.