Morphological taxonomy and molecular divergence of four balitorid species (subfamily: Nemachelinae) from Central Himalaya, India

The fishes in this study belong to the difficult group. It is difficult to identify about more than 50 nemacheilid loach species in India, mainly due to the poor quality of the original descriptions, the lack of good reviews, and the similarity of a number of the banded species. In view of this, a morphometric and genetic study was conducted on four species that have been documented in Central Himalayan region of India. Using comparative methods, a contribution to the knowledge about the variability of four Himalayan hillstream loaches, a molted loach Acanthocobitis botia (Hamilton, 1822), Nemacheilus corica (Hamilton, 1822), a creek loach Schistura beavani (Gunther, 1868), and Schistura montana (McClelland, 1838), was accomplished. Morphometric data were analyzed by univariate (CV and analysis of variance) and multivariate analyses (discriminant function analysis and cluster analysis). Based on the results of these statistical analyses, generally all four species grouped into their own species cluster with minimal overlap between two species of genus Schistura. Mitochondrial DNA cytochrome b (Cyt b) gene analysis revealed 7.7-17.6% genetic distances among the four species. Molecular phylogenetic relationship among these species and other Balitoridae species was investigated using published mitochondrial Cyt b sequences. Dendrograms obtained by the maximum likelihood and maximum parsimony method analyses exhibited the same topology. According to this topology, all the four species represented distinct species group and A. botia form the most distinct species while S. beavani and S. montana are clustered together with Nemacheilus species to form a single group. This work may build the base for the revision of taxonomic identity of fishes of the family Balitoridae. The results may further help to enhance the knowledge of the ichthyologists in understanding the fish fauna of India and assist them in planning conservation and management strategies for the propagation of these less studied small indigenous species along their natural range of distribution.

A new species of Triplophysa (Nemacheilidae: Cypriniformes), from Guangxi, southern China

A new species, Triplophysa huapingensis, is described from the Hongshuihe River, Guangxi, China. The new species is distinguished from other species of Triplophysa by the following combination of characters: body covered with scales, lateral line complete, eyes not degenerate, dorsal fin truncate, caudal fin forked, tip of pelvic fin not reaching anus, eight branched rays of dorsal fin, six branched rays of pelvic fin, 16 branched rays of caudal fin, grey and black diffused blotches on dorsal and lateral head and body. A key to all recorded species of Triplophysa in the Xijiang River system is provided.

[Morphologic differentiation analysis for rounded caudal fin group of Oreonectes (Balitoridae) from China]

Morphological characteristics were compared between three recorded species of rounded caudal fin Oreonectes and specimens collected from Guan'an of Guangxi. The results showed the Oreonectes sp. from Guan'an was distinguished from O. anphthalmus. Although some morphologic differentiations existed among Oreonectes sp., O. polystigmus, and O. platycephalus, their differentiations were not enough to distinguish between them. Consequently, we used multivariate morphometrics to determine their morphologic differentiation. Twenty-six frame characteristics and 20 general characteristics of 63 specimens were measured. The results of the Principal Component Analysis showed that Oreonectes sp. and O. polystigmus, and Oreonectes sp. and O. platycephalus occupied obviously different areas in the scatter plot. It is suggested that the specimens collected from Guan'an may be a cryptic new species of Oreonectes. However, its taxonomic status should be decided by evidence from anatomical and molecular biological studies.

Enobarbus is a synonym of Lepidocephalichthys (Osteichthyes, Cobitidae)

External and internal morphological characters of the holotype of Enobarbus maculatus were examined and compared with those of other cobitid species to verify whether Enobarbus is a distinct genus. Analyses of radiographs demonstrated that the neural spines and the pterygiophores of the dorsal fin are of irregular shape, often doubled, reduced or bent. The holotype of E. maculatus bears an ossified structure on the last pectoral-fin ray, a structure otherwise known only from males of the genus Lepidocephalichthys. In Lepidocephalichthys, the shape of the ossified structure is species-specific, and the structure of Enobarbus is very similar to that of Lepidocephalichthys thermalis, the only other known species of the family Cobitidae occurring at the type locality of Enobarbus. Furthermore, the cranial and the axial skeleton of E. maculatus is similar to that of L. thermalis, except for the pterygiophores and the neural spines, that are strongly malformed in Enobarbus. In general, the results presented here show that the genus Enobarbus shares the most important characters (thickening of last two pectoral-fin rays in males, structure of swimbladder capsule, shape of neurocranium and suborbital spine) with Lepidocephalichthys and that its long dorsal fin is correlated with strong malformations of the vertebral column and the fin ray insertions. Consequently, the only known specimen of Enobarbus is most likely a teratological male of L. thermalis, and Enobarbus is a junior synonym of Lepidocephalichthys.

Balitora eddsi, a new species of hillstream loach (Ostariophysi: Balitoridae) from Nepal

A new species of hillstream loach Balitora eddsi is described from the Karnali River drainage in south-western Nepal. The new species is distinguished from all its congeners by possessing the following combination of characters: six to seven unbranched pectoral-fin rays, pelvic-fin length 12-14% standard length (L(S)), dorsal surface without circular or irregular shaped dark blotches, snout pointed, median lobe between anterior rostral barbels pointed posteriorly, dorsal-fin origin posterior to pelvic-fin origin, lateral line scales 66-67, caudal peduncle length 22-23.2% L(S), caudal peduncle depth 4.1-4.2 times its length.

Molecular phylogeographic analyses of the loach Oxynoemacheilus bureschi reveal post-glacial range extensions across the Balkans

Rivers on the Balkan Peninsula can be separated into ichthyofaunistic areas with different endemic fish species. The Vardar River contains a particularly large number of endemics, indicating its complete and long-term isolation from neighbouring river systems. One of the few species shared with other rivers is the loach species Oxynoemacheilus bureschi. In this study, the genetic analyses of 175 individuals of O. bureschi from 17 sites, covering the entire distribution of the species, including the Rivers Vardar (= Axios), Struma (= Strymon), Mesta (= Nestos) and Danube, were performed using one mitochondrial and one nuclear marker. Genetic differentiation among populations was in general low. Shared haplotypes were common and occurred even between distant localities and different river systems. This points to a high degree of gene flow among populations and rejects the hypothesis that the population in the Vardar River represents a relict from an early colonization of the Balkan Peninsula. In contrast, the results suggest that populations in the Vardar River, as well as those in the Danube River, are of recent origin, and a human-mediated introduction cannot be excluded. On the other hand, the populations in the Aggitis River, a left tributary of the lower Struma River, were clearly separated from the rest of the species and represent a long-term isolated lineage. Demographic analyses suggest a recent population expansion for O. bureschi, in which the population in the Aggitis River was not involved.

Molecular phylogeny of the Cobitoidea (Teleostei: Cypriniformes) revisited: position of enigmatic loach Ellopostoma resolved with six nuclear genes

Molecular variation in six nuclear genes provides substantive phylogenetic evidence for the recognition of a new cypriniform family, the Ellopostomatidae, to include the enigmatic Southern Asia loach genus Ellopostoma. The current six loach families form a monophyletic group, with the Nemacheilidae as the sister group to Ellopostomatidae; Vaillantellidae forms the sister group to all families exclusive of Botiidae. While the superfamily Cobitoidea includes eight families, the monophyly of this large clade within the Cypriniformes remains a vexing problem despite extensive molecular analyses and is in need of further investigation.

Gill-filament ossifications: a possible morphological synapomorphy uniting the families Balitoridae and Cobitidae (Ostariophysi: Cypriniformes)

Ossifications associated with the gill filaments of members of the Balitoridae and Cobitidae are described for the first time. Although gill-filament ossifications are common in teleosts, similar ossifications were not observed in other members of the order Cypriniformes. Their presence is interpreted as a shared and derived character uniting the families Balitoridae and Cobitidae as a monophyletic group.

[On the systematics and phylogeography of eight-barbel loaches the genus Lefua (Cobitoidea: Nemacheilidae): mtDNA typing of L. pleskei]

Comparative analysis of personal sequence data for the mtDNA control region (926 to 928 bp) from eight-barbel loaches inhabiting eight localities in the Amur River basin (4) and the Sea of Japan (4) and the GeneBank/NCBI data for the Lefua individuals from the other regions of the world showed that eight-barbel loaches from Primorskii krai water basins were marked by a specific group of mtDNA haplotypes. This finding is considered as supporting the species status of L. pleskei. Genetic distances within L. pleskei are small (on average 0.355) and close to those within L. nikkonis (on average 0.48%). The distances between this species pair are the least (on average 2.15%) among all other pairs compared. In MP, ML, and Bayesian trees, L. pleskei and L. nikkonis haplotypes formed a common clade with high statistically significant support. In all tree variants, L. costata mtDNA haplotypes were located out of the group of interest. A clade consisting of highly diverged lineages of Lefua sp. and L. echigonia haplotypes occupied even more independent position. The mtDNA haplotypes of L. pleskei and L. costata from the Amur River basin were evolutionary young and derived from the haplotypes found in these species from the Sea of Japan (L. pleskei) or the Yellow Sea (L. costata) basins. It is thereby suggested that both species rather recently migrated into the Amur River system. According to the molecular clock data, basal diversification of the eight-barbel loach lineages took place at the end of middle Miocene (about 11 to 12 Myr ago), while divergence of L. pleskei and L. costata ancestral forms probably occurred approximately, 5 Myr ago. Since all main lineages of eight-barbel loaches were found in the Sea of Japan basin (continental coastline and the islands), the divergence order and dispersal patterns of the Lafua species might have been largely determined by the geological development pattern of this water body and the adjacent territories.

Zebrafish dentition in comparative context

Studies of the zebrafish (Danio rerio) promise to contribute much to an understanding of the developmental genetic mechanisms underlying diversification of the vertebrate dentition. Tooth development, structure, and replacement in the zebrafish largely reflect the primitive condition of jawed vertebrates, providing a basis for comparison with features of the more extensively studied mammalian dentition. A distinctive derived feature of the zebrafish dentition is restriction of teeth to a single pair of pharyngeal bones. Such reduction of the dentition, characteristic of the order Cypriniformes, has never been reversed, despite subsequent and extensive diversification of the group in numbers of species and variety of feeding modes. Studies of the developmental genetic mechanism of dentition reduction in the zebrafish suggest a potential explanation for irreversibility in that tooth loss seems to be associated with loss of developmental activators rather than gain of repressors. The zebrafish and other members of the family Cyprinidae exhibit species-specific numbers and arrangements of pharyngeal teeth, and extensive variation in tooth shape also occurs within the family. Mutant screens and experimental alteration of gene expression in the zebrafish are likely to yield variant tooth number and shape phenotypes that can be compared with those occurring naturally within the Cyprinidae. Such studies may reveal the relative contribution to trends in dental evolution of biases in the generation of variation and sorting of this variation by selection or drift.

Using zebrafish to investigate cypriniform evolutionary novelties: functional development and evolutionary diversification of the kinethmoid

Although the zebrafish has become a popular model organism for biomedical studies, we propose that the wealth of morphological novelties that characterize this cypriniform fish makes it well suited for investigating the development of evolutionary innovations. Morphological novelties associated with feeding in cypriniform fishes include: a unique structure of the pharyngeal jaws in which the lower pharyngeal jaws are enlarged and opposed to a pad on the basioccipital process; a palatal organ found on the roof of the buccal chamber that is thought to help process detrital food within the buccal chamber; and, the kinethmoid, a novel ossification that effects a unique means of premaxillary protrusion. We present new morphological and developmental data and review functional data regarding the role of the kinethmoid in premaxillary protrusion in the zebrafish. Premaxillary protrusion plays an important role in effective prey acquisition in teleosts and the evolution of a unique means of premaxillary protrusion within Cypriniformes may have led to a number of trophic radiations within this clade. Ontogenetic data from zebrafish show that substantial premaxillary protrusion is not seen until these fish have undergone metamorphosis at which point the adductor mandibulae musculature becomes divided and all ligamentous attachments become established. A comparative study of families within Cypriniformes shows diverse morphologies of the kinethmoid. The morphological diversification that characterizes the kinethmoid suggests that this feeding structure has played a role in trophic radiations within Cypriniformes, since the morphology of this feature is correlated with feeding habits.

Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species

The evolutionary relationships of species of Danio and the monophyly and phylogenetic placement of the genus within the family Cyprinidae and subfamily Rasborinae provide fundamentally important phyloinformatics necessary for direct evaluations of an array of pertinent questions in modern comparative biology. Although the genus Danio is not one of the most diverse within the family, Danio rerio is one of the most important model species in biology. Many investigations have used this species or presumed close relatives to address specific questions that have lasting impact on the hypothesis and theory of development in vertebrates. Largely lacking from this approach has been a holistic picture of the exact phylogenetic or evolutionary relationships of this species and its close relatives. One thing that has been learned over the previous century is that many organismal attributes (e.g., developmental pathways, ecologies, behaviors, speciation) are historically constrained and their origins and functions are best explained via a phylogenetic approach. Herein, we provide a molecular evaluation of the phylogenetic placement of the model species Danio rerio within the genus Danio and among hypothesized closely related species and genera. Our analysis is derived from data using two nuclear genes (RAG1, rhodopsin) and five mitochondrial genes (ND4, ND4L, ND5, COI, cyt b) evaluated using parsimony, maximum likelihood, and Bayesian analyses. The family Cyprinidae is resolved as monophyletic but the subfamily Rasborinae (priority over Danioinae) is an unnatural assemblage. Danio is identified as a monophyletic group sister to a clade inclusive of the genera Chela, Microrasbora, Devario, and Inlecypris, not Devario nor Esomus as hypothesized in previous studies. Danio rerio is sister to D. kyathit among the species of Danio evaluated in this analysis. Microrasbora and Rasbora are non-monophyletic assemblages; however, Boraras is monophyletic.

Incongruence between mtDNA phylogeny and morphologial and ecological characters in loaches of the genus Lefua (Balitoridae, Cypriniformes)

To elucidate the phylogenetic position of Lefua loaches from Aichi and Shizuoka Prefectures of Honshu Island, Japan, we determined their nucleotide sequences for the mitochondrial D-loop region and compared these to sequences from four other Lefua species: L. costata, L. nikkonis, L. echigonia, and L. sp. Loaches identified as L. sp. on the basis of morphology comprised a clade (the L. sp. Tokai population) that grouped together with L. echigonia; hence, the processes involved in evolution within the genus Lefua were unclear. We performed randomly amplified polymorphic DNA (RAPD) analyses to obtain genetic information on nuclear DNA. The RAPD patterns of the L. sp. Tokai population differed from those of the local L. echigonia and L. sp. populations. The L. sp. Tokai population was similar to L. echigonia with regard to mitochondrial DNA but differed from L. echigonia and L. sp. with respect to nuclear DNA; this indicated that the evolutionary background of the L. sp. Tokai population was unique. We suggest that introgression of mitochondria occurred from L. echigonia to the L. sp. Tokai population, and speculate on the process of evolution of the latter population of Lefua. As with six L. echigonia populations and two L. sp. populations, we regard the L. sp. Tokai population as an evolutionary significant unit (ESU) that qualifies for protection as an endangered loach.

The gynogenetic reproduction of diploid and triploid hybrid spined loaches (Cobitis: Teleostei), and their ability to establish successful clonal lineages—on the evolution of polyploidy in asexual vertebrates

Polyploidisation is assumed to have played a significant role in the evolution of hybrid asexual lineages. The virtual absence of natural asexual systems in which more than a single ploidy level successfully establishes successful independent clonal lineages is generally explained by the strong effects of polyploidisation on fitness. Experimental crosses were made between diploid and triploid asexual Cobitis elongatoides x C. taenia hybrids (female) and both parental spined loach species (male). Genotyping of the progeny using allozymes and multilocus DNA fingerprinting, along with flow cytometric measurement of ploidy level, demonstrated the occurrence of gynogenetic reproduction in both female biotypes. The incorporation of the sperm genome occurred in some progeny, giving rise to a higher ploidy level, but the rate of polyploidisation differed significantly between the diploid and triploid females. These outcomes are consistent with the existence of developmental constraints on tetraploidy, which determine the rarity of tetraploids in natural populations. No cases of ploidy level reduction were observed. Since diploid and triploid hybrid populations occur where the lack of potential progenitor excludes the possibility of de novo origin, it is probable that both diploid and triploid females can establish successful clonal lineages. Spined loaches represent a unique example, among asexual vertebrates, where more than one ploidy level can establish persistent clonal lineages, which are reproductively independent of one another.

Morphological variation in the Weberian apparatus of Cypriniformes

Cypriniformes (which includes the minnows, carps, loaches, algae-eaters, stone loaches, and suckers) is a morphologically diverse and incredibly speciose order of teleosts. It has been suggested that a number of evolutionary innovations, key to improved hearing and feeding, have played an important role in cypriniform fishes' success. One such innovation, the Weberian apparatus, is a novel assemblage of vertebral elements and modified ribs that relay and amplify sound pressure changes from the gas bladder to the inner ear. The Weberian apparatus unites Cypriniformes with other major orders into an extremely species-rich group of fishes, the Otophysi. Together, otophysan fishes comprise one of the largest groups of fishes in the world, as well as the majority of freshwater fishes. Here we present a detailed comparison of the Weberian apparatus in a number of cypriniform families using cleared and stained specimens. We present data regarding inter- and intrafamilial morphological variation within Cypriniformes. With few, but evolutionarily important, exceptions we find that diagnostic features of the Weberian apparatus characterize each family. Interspecific variation within each of the families Balitoridae, Gyrinocheilidae, and Catostomidae is only slight, whereas variation among subfamilies within Cyprinidae and Cobitidae is far more significant. This comparative study identifies a number of distinct morphologies, some of which appear highly correlated with ecological niche. For example, inhabiting swift-moving waters appears to be a key factor in the encapsulation of the anterior gas bladder in some cobitids, balitorids, and gobionin cyprinids.

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).

Molecular phylogeny of the Southeast Asian freshwater fish family Botiidae (Teleostei: Cobitoidea) and the origin of polyploidy in their evolution

The freshwater fish family Botiidae is represented by seven genera on the Indian subcontinent and in East and Southeast Asia and includes diploid as well as evolutionary tetraploid species. We present a phylogeny of Botiidae including 33 species representing all described genera using the mitochondrial cytochrome b and 12s rRNA genes to reconstruct the phylogenetic relationships among the genera and to estimate the number of polyploidisation events during their evolution. Our results show two major lineages, the subfamilies Leptobotiinae with the genera Leptobotia and Parabotia and Botiinae with the genera Botia, Chromobotia, Sinibotia, Syncrossus, and Yasuhikotakia. Our results suggest that two species that were traditionally placed into the genus Yasuhikotakia form a monophyletic lineage with the species of Sinibotia. A review of the data on the ploidy level of the included species shows all diploid species to belong to Leptobotiinae and all tetraploid species to Botiinae. A single polyploidisation event can therefore be hypothesised to have occurred in the ancestral lineage leading to the Botiinae.

Vicariance, colonisation, and fast local speciation in Asia Minor and the Balkans as revealed from the phylogeny of spined loaches (Osteichthyes; Cobitidae)

We reconstruct the phylogeny of the morphologically diagnosable subgenera Bicanestrinia, Beysehiria, and Cobitis sensu stricto of the genus Cobitis from Asia Minor and the Balkans. We used the complete cytochrome b gene of 65 specimens in order to infer their evolutionary history in this zoogeographically interesting area. Our phylogeographic analysis did not evidence the previously suggested monophyly of the Bicanestrinia subgenus but revealed five monophyletic lineages in the area: the lineages Bicanestrinia I-IV including all species of Bicanestrinia plus the lineage Cobitis s. str. The monotypic subgenus Beysehiria from Lake Beysehir in Anatolia was closely related to the syntopic population of C. turcica and nested inside the lineage Bicanestrinia III. The strictly allopatric distribution of the four lineages of Bicanestrinia suggests that vicariance has played a major role in the diversification of Bicanestrinia. All analysed species of Cobitis s. str. from Asia Minor and Balkans were closely related to Cobitis s. str. from Central Europe, the Danube basin and the Caucasus, indicating at least two colonisation events into Asia Minor and the Balkans. A third, recent colonisation event led to the presence of C. strumicae, generally restricted to the Aegean Sea drainage, in the Danube basin. Besides the evidences of vicariance and colonisation events in the phylogenetic history of the genus Cobitis in Asia Minor and the Balkans, our analysis suggested also a rapid morphological evolution of C. bilseli in a lacustrine environment. Application of Cobitis mitochondrial cytochrome b clocks of 0.68% sequence divergence per million years (MY) suggest that the split between the five major lineages happened approximately 12.4-17.6 MYA, and according to the lack of basal resolution of this monophyletic group probably the split of all lineages happened within a narrow time window.

Comparison of evolutionary rates in the mitochondrial DNA cytochrome b gene and control region and their implications for phylogeny of the Cobitoidea (Teleostei: Cypriniformes)

It is widely accepted that mitochondrial DNA (mtDNA) control region evolves faster than protein encoding genes with few exceptions. In the present study, we sequenced the mitochondrial cytochrome b gene (cyt b) and control region (CR) and compared their rates in 93 specimens representing 67 species of loaches and some related taxa in the Cobitoidea (Order Cypriniformes). The results showed that sequence divergences of the CR were broadly higher than those of the cyt b (about 1.83 times). However, in considering only closely related species, CR sequence evolution was slower than that of cyt b gene (ratio of CR/cyt b is 0.78), a pattern that is found to be very common in Cypriniformes. Combined data of the cyt b and CR were used to estimate the phylogenetic relationship of the Cobitoidea by maximum parsimony, neighbor-joining, and Bayesian methods. With Cyprinus carpio and Danio rerio as outgroups, three analyses identified the same four lineages representing four subfamilies of loaches, with Botiinae on the basal-most clade. The phylogenetic relationship of the Cobitoidea was ((Catostomidae+Gyrinocheilidae)+(Botiinae+(Balitorinae+(Cobitinae+Nemacheilinae)))), which indicated that Sawada's Cobitidae (including Cobitinae and Botiinae) was not monophyletic. Our molecular phylogenetic analyses are in very close agreement with the phylogenetic results based on the morphological data proposed by Nalbant and Bianco, wherein these four subfamilies were elevated to the family level as Botiidae, Balitoridae, Cobitidae, and Nemacheilidae.

Phylogenetic relationships among the Ibero-African cobitids (Cobitis, cobitidae) based on cytochrome b sequence data

We estimated the phylogenetic relationships of all Ibero-African spined loaches of the genus Cobitis using the complete mitochondrial cytochrome b gene (1140bp). We analysed 93 individuals of seven cobitid species found in all the principal drainages of the Iberian Peninsula and North Africa. A molecular phylogeny was used to revise current systematics of the Ibero-African Cobitis species and to infer a biogeographical model for Cobitis in the Western Mediterranean area during the Cenozoic period. Phylogenetic analysis provided support for the monophyly of two mtDNA clades: Clade A or Italian Clade with the Italian species (C. bilineata, C. zanandreai), and Clade B or the Ibero-African Clade. The Ibero-African Clade included all species endemic for the Iberian Peninsula (C. vettonica, C. calderoni, and C. paludica) and North Africa (C. maroccana). The species C. paludica does not constitute a natural group, and could be divided into at least four monophyletic mtDNA lineages with moderate to high bootstrap values and posterior probability support. Phylogenetic relationships of the Ibero-African species were not resolved satisfactorily, but in all analyses C. calderoni from Northern Iberian Peninsula was basal. We have re-calibrated a molecular clock for the genus Cobitis (0.68% per million year by pairwise) using populations inhabiting both sides of the Gibraltar Strait. Application of this Cobitis mtDNA clock provides evidence that the Messinian salinity crisis played a primary role in the diversification of some Ibero-African cobitid species. The basal polytomies of the Ibero-African Clade might suggest that all mtDNA lineages diversified rapidly.

Genetic monitoring of wild and repatriated populations of endangered razorback sucker (Xyrauchen texanus, Catostomidae, Teleostei) in Lake Mohave, Arizona-Nevada

The Native Fishes Work Group, formed in 1991, developed and implemented a protocol to enhance the dwindling razorback sucker population in Lake Mohave, Arizona-Nevada. This large, genetically diverse population is severely reduced in size as a result of recruitment failure associated with predation on larvae. To circumvent this problem, wild larvae are captured, reared in protective custody until they are large enough to escape predation, and then released back into the lake. We present results of a monitoring program designed to assess the effectiveness of the sampling design in transmitting the high genetic diversity found in wild adults. Variation in a fragment from the mitochondrial DNA gene cytochrome b was examined by analysis of single-stranded polymorphisms and direct sequencing. Samples were characterized from three life history stages. Characterization of wild adults verified previous results that identified considerable diversity and provided baseline data. Samples of larvae from several temporal collections from throughout the spawning season and four geographical areas were characterized for 7 years (1997-2003) to assess the transmission of genetic variation from wild adults to larvae. Several analyses identified significant differences among temporal collections, resulting from sampling errors associated with finite number of females spawning at a given time and place. Comparisons among areas and years failed to identify significant variation, indicating that pooled collections for each year possess the same levels and patterns of genetic variation. Examination of repatriates representing 11 years (1992-2002) also failed to identify significant differences among cohorts; however, some sample sizes were small and the amova may lack sufficient power to detect differences. Contrasts of wild adults, larvae, and repatriates identified statistically significant differences among collections within these three groups; however, levels of variation are small and not biologically meaningful. More importantly, this analysis failed to detect significant differences among adults, larvae, and repatriates indicating that the program has been achieving its goal of transmitting variation from adults through the larvae and into the repatriate population. The reproductive capability of repatriates has not been examined, so it is unknown if the program will maintain genetic variation found in the original adult population. This will be most easily achieved by periodic monitoring of genetic variation in larval samples. If levels of variation become reduced in repatriates, levels and patterns of diversity in larvae are also expected to become reduced, and deviations in estimates of genetic diversity may become larger and more frequent. If this is the case, intervention may be necessary to ensure that certain individuals are not over-represented in the repatriate population.

Identification of 24 genes and two pseudogenes coding for olfactory receptors in Japanese loach, classified into four subfamilies: a putative evolutionary process for fish olfactory receptor genes by comprehensive phylogenetic analysis

Twenty-four olfactory receptor (OR) genes and two pseudogenes have been identified in the genome of Japanese loach (Misgurnus anguillicaudatus). The genes were classified into four subfamilies according to the similarity of the amino acid sequences. In each subfamily, members showed high sequence similarity not only to each other but also to orthologues of other fish species. The number of members in each OR subfamily was roughly estimated to be from 3 to 10 by genomic Southern blot analysis. The genes of all four OR subfamilies were shown to express on olfactory neurons of the olfactory epithelium by in situ hybridization analysis. Two major features of fish OR genes were found by comprehensive and comparative analyses on OR genes of Japanese loach and other fish species including catfish, zebrafish and pufferfish. First, the phylogenetic tree comprising of representative subfamily members suggests the existence of several prototype genes common to the genomes of many fish species. Second, when all members of orthologous subfamilies identified in each clade of the tree are integrated, the members of a single species comprise a monophyletic group. This means that 'intraspecies' sequence homology, that is, homology among paralogous genes of the same subfamily in a species, is higher than 'interspecies' homology, that is, homology between orthologous genes of different species. This suggests that the subfamily members of a species have evolved recently. Taken together, fish OR genes have evolved from a limited number of prototype genes common to most fish species, and several genes in a subfamily have diversely evolved in each species from each prototype.

Phylogenetic relationships of the cypriniformes tested by mtDNA 12S rRNA sequence variations

Cypriniformes is the largest order of freshwater fishes. The phylogenetic relationships of the Cypriniformes have been studied by many investigators based on morphological characters, but no agreement has been reached. In the present paper, complete mitochondrial 12S rRNA sequences of five families of the Cypriniformes were determined and analyzed to test the present morphological hypotheses. After alignment, there are 1000 sites, among which 467 sites are in stems and 533 sites in loops. 395 sites are variable, and of which 267 are informative. Neighbor-joining and Maximum Parsimony methods were employed for phylogenetic analysis. The results indicate that the cyprinids form a monophyletic group while the non-cyprinid cypriniforms form another one, which is in accordance with the hypothesis proposed by Siebert. The Cyprinidae consists of three main clades, the Danionini, the Cyprinini, and the Leuciscini. However, in the non-cyprinid cypriniforms, the relationships could not be resolved clearly. The Cobitidae is polyphyletic. Homalopteridae, Noemacheilinae and Cobitinae may have closer relationships.