Evidence for Selection on Mitochondrial OXPHOS Genes in the Mediterranean Killifish Aphanius fasciatus Valenciennes, 1821

Mitochondrial oxidative phosphorylation (OXPHOS) genes are a system subject to selection under determined environmental constraints despite a neutral evolution model that has long been hypothesized for the mitochondrial genome. In this study, the sequences of ND1, Cytb, and COI OXPHOS genes were analyzed in six populations of the eurythermal and euryhaline killifish A. fasciatus, to detect non-synonymous mutations leading to amino acid changes and to check whether selection acted on them using tests of recombination and selection. The results indicate a high COI and Cytb gene diversity and a high percentage of private haplotypes in all populations. In the Greek population, non-synonymous nucleotide substitutions were observed in the N-terminal region of COI and Cytb. Positively selected sites were also found. The information we obtained from the mitochondrial DNA sequences of A. fasciatus adds to the growing data on selective pressure acting on mitochondrial DNA in non-model species. These results should be explored from the perspective of the local adaptation of eurythermal and euryhaline species and supported using experimental evidence to better understand the interplay between historical climatic events and local adaptation and how each of them contributes to shaping the genetic structure of this species.

Diversity, phylogeny and intraspecific variability of Paradiplozoon species (Monogenea: Diplozoidae) parasitizing endemic cyprinoids in the Middle East

Diplozoidae are common monogenean ectoparasites of cyprinoid fish, with the genus Paradiplozoon being the most diversified. Despite recent studies on Diplozoidae from Europe, Africa and Asia, the diversity, distribution and phylogeny of this parasite group appears to be still underestimated in the Middle East. The objective of this study was to investigate the diversity, endemism and host specificity of diplozoids parasitizing cyprinoid fish from the Middle East, considering this region as an important historical interchange of fish fauna, and to elucidate the phylogenetic position of Middle Eastern Paradiplozoon species within Diplozoidae. Four Paradiplozoon species were collected from 48 out of 94 investigated cyprinoid species. Three known species, Paradiplozoon homoion, Paradiplozoon bliccae and Paradiplozoon bingolensis, were recorded on new cyprinoid host species, and a new species, Paradiplozoon koubkovae n. sp., was recorded on Luciobarbus capito and Capoeta capoeta from the Caspian Sea basin in Iran and Turkey. Paradiplozoon bliccae, exhibiting a wide host range in the Middle East, expressed both morphological and genetic intraspecific variabilities. The four Paradiplozoon species collected in the Middle East were placed in divergent clades, showing the rich evolutionary history of diplozoid parasites in the Middle East. Our study also revealed that two lineages of African diplozoids have a Middle Eastern origin. We stress the importance of applying an integrative approach combining morphological, ecological and molecular methods to reveal the real diversity of diplozoids.

Monogeneans and chubs: Ancient host-parasite system under the looking glass

Host-parasite coevolution is one of the fundamentals of evolutionary biology. Due to the intertwined evolutionary history of two interacting species and reciprocal coadaptation processes of hosts and parasites, we can expect that studying parasites will shed more light onto the evolutionary processes of their hosts. Monogenea (ectoparasitic Platyhelminthes) and their cyprinoid fish hosts represent one of the best models for studying host-parasite evolutionary relationships using a cophylogenetic approach. These parasites have developed remarkably high host specificity, where each host species often serves as a potential host for its own host-specific monogenean species. Here, the cophylogenetic relationships in the Dactylogyrus-Squalius system was investigated, as Squalius is one of several cyprinoid genera with puzzling phylogeography and inhabits all four major peri-Mediterranean peninsulas. Of 29 endemic Squalius species examined for the presence of Dactylogyrus parasites, a total of 13 Dactylogyrus species were collected from the gills of 20 Squalius species across a wide range of distribution. Phylogenetic reconstruction revealed a polyphyletic origin for Dactylogyrus species parasitizing congeneric Squalius, with four major clades being recognized. On the basis of the delimitation of host specificity, strict specialists parasitizing single host species, geographic specialists parasitizing congeners in a limited geographical region, and true generalists parasitizing congeners in various geographical regions were recognized in Dactylogyrus species parasitizing Squalius. The phylogenetic reconstruction of Squalius hosts revealed two major clades, the first encompassing only peri-Mediterranean species and the second including species from other Euro-Asian regions. Distance-based cophylogenetic methods did not reveal a statistically significant global cophylogenetic structure in the studied system; however, several host-parasite links among Iberian endemic species contributed significantly to the overall structure. The widest host range and associated genetic variability were recorded for D. folkmanovae, parasitizing nine Squalius species, and D. vistulae, parasitizing 13 Squalius species. Two different dispersion mechanisms and morphological adaptations to Squalius hosts were clearly reflected in the contrasting cophylogenetic patterns for these two species with different levels of host specificity. While host-parasite cospeciation plays an important role in diversification within D. folkmanovae, diversification within D. vistulae is driven mainly by host switching.

An integrative phylogenetic approach for inferring relationships of fossil gobioids (Teleostei: Gobiiformes)

The suborder Gobioidei is among the most diverse groups of vertebrates, comprising about 2310 species. In the fossil record gobioids date back to the early Eocene (c. 50 m.y. ago), and a considerable increase in numbers of described species is evident since the middle Miocene (c. 16 m.y. ago). About 40 skeleton-based gobioid species and > 100 otolith-based species have been described until to date. However, assignment of a fossil gobioid species to specific families has often remained tentative, even if well preserved complete specimens are available. The reasons are that synapomorphies that can be recognized in a fossil skeleton are rare (or absent) and that no phylogenetic framework applicable to gobioid fossils exists. Here we aim to overcome this problem by developing a phylogenetic total evidence framework that is suitable to place a fossil skeleton-based gobioid at family level. Using both literature and newly collected data we assembled a morphological character matrix (48 characters) for 29 extant species, representing all extant gobioid families, and ten fossil gobioid species, and we compiled a multi-gene concatenated alignment (supermatrix; 6271 bp) of published molecular sequence data for the extant species. Bayesian and Maximum Parsimony analyses revealed that our selection of extant species was sufficient to achieve a molecular ‘backbone’ that fully conforms to previous molecular work. Our data revealed that inclusion of all fossil species simultaneously produced very poorly resolved trees, even for some extant taxa. In contrast, addition of a single fossil species to the total evidence data set of the extant species provided new insight in its possible placement at family level, especially in a Bayesian framework. Five out of the ten fossil species were recovered in the same family as had been suggested in previous works based on comparative morphology. The remaining five fossil species had hitherto been left as family incertae sedis. Now, based on our phylogenetic framework, new and mostly well supported hypotheses to which clades they could belong can be presented. We conclude that the total evidence framework presented here will be beneficial for all future work dealing with the phylogenetic placement of a fossil skeleton-based gobioid and thus will help to improve our understanding of the evolutionary history of these fascinating fishes. Moreover, our data highlight that increased sampling of fossil taxa in a total-evidence context is not universally beneficial, as might be expected, but strongly depends on the study group and peculiarities of the morphological data.

Correlation between acoustic divergence and phylogenetic distance in soniferous European gobiids (Gobiidae; Gobius lineage)

In fish, species identity can be encoded by sounds, which have been thoroughly investigated in European gobiids (Gobiidae, Gobius lineage). Recent evolutionary studies suggest that deterministic and/or stochastic forces could generate acoustic differences among related animal species, though this has not been investigated in any teleost group to date. In the present comparative study, we analysed the sounds from nine soniferous gobiids and quantitatively assessed their acoustic variability. Our interspecific acoustic study, incorporating for the first time the representative acoustic signals from the majority of soniferous gobiids, suggested that their sounds are truly species-specific (92% of sounds correctly classified into exact species) and each taxon possesses a unique set of spectro-temporal variables. In addition, we reconstructed phylogenetic relationships from a concatenated molecular dataset consisting of multiple molecular markers to track the evolution of acoustic signals in soniferous gobiids. The results of this study indicated that the genus Padogobius is polyphyletic, since P. nigricans was nested within the Ponto-Caspian clade, while the congeneric P. bonelli turned out to be a sister taxon to the remaining investigated soniferous species. Lastly, by extracting the acoustic and genetic distance matrices, sound variability and genetic distance were correlated for the first time to assess whether sound evolution follows a similar phylogenetic pattern. The positive correlation between the sound variability and genetic distance obtained here emphasizes that certain acoustic features from representative sounds could carry the phylogenetic signal in soniferous gobiids. Our study was the first attempt to evaluate the mutual relationship between acoustic variation and genetic divergence in any teleost fish.

Evolutionary history of the Pelasgus minnows (Teleostei: Leuciscidae), an ancient endemic genus from the Balkan Peninsula

The Balkans are one of the European biodiversity hotspots, hosting outstandingly rich, yet threatened, flora and fauna. This region hosts one of the richest endemic freshwater ichthyofauna in Europe, including several genera occurring exclusively here. One of these is the genus of the primary freshwater minnows Pelasgus, which was designated only in 2007. The genus is one of the most ancient genera of the family Leuciscidae and comprises seven small-bodied species, inhabiting slower, well-vegetated courses of rivers. This work is the first molecular multilocus phylogeny of the genus, based on one mitochondrial and three nuclear markers. In total, 305 individuals across almost entire distribution range of the genus were analysed. We inferred the evolutionary history of the species by comparing the results of our calibrated multilocus coalescent species-tree to palaeogeological events. The diversification of the genus started in the early Miocene and continued through to the beginning of Pleistocene. We identified the regions of the oldest colonization by Pelasgus, the drainages of the ancient lakes Ohrid and Prespa, and the southernmost part of the Peloponnese, hosting Pelasgus minutus, P. prespensis and P. laconicus, respectively. We showed that P. prespensis is not endemic to Lake Prespa, as previously thought; it occurs also in the Albanian River Devoll. This corroborates the emerging opinion that the endemic taxa of ancient lakes evolved within larger-scale historic drainages and not only within the lakes. Our results showed that the species with the most recent common ancestor of the early Pliocene origin, P. thesproticus, P. epiroticus, P. stymphalicus and P. marathonicus, have neighbouring distribution ranges. Pelasgus epiroticus is especially interesting, not only for its pronounced genetic diversity with a geographic pattern, but also for being found at three localities within the native distribution range of P. stymphalicus as a result of a translocation. At two of these localities, we identified hybrids between the two species, and at one of them, the genetically pure native species was not found at all. This points to a threat of the loss of the native ichthyofauna due to unintentional translocations.

Genetic hypervariability of a Northeastern Atlantic venomous rockfish

BACKGROUND

Understanding the interplay between climate and current and historical factors shaping genetic diversity is pivotal to infer changes in marine species range and communities' composition. A phylogeographical break between the Atlantic and the Mediterranean has been documented for several marine organisms, translating into limited dispersal between the two basins.

METHODS

In this study, we screened the intraspecific diversity of 150 individuals of the Madeira rockfish (Scorpaena maderensis) across its distributional range (seven sampling locations in the Atlantic and Mediterranean basins) using the mitochondrial control region and the nuclear S7 first intron.

RESULTS

The present work is the most comprehensive study done for this species, yielding no genetic structure across sampled locations and no detectable Atlantic-Mediterranean break in connectivity. Our results reveal deep and hyper-diverse bush-like genealogies with large numbers of singletons and very few shared haplotypes. The genetic hyper-diversity found for the Madeira rockfish is relatively uncommon in rocky coastal species, whose dispersal capability is limited by local oceanographic patterns. The effect of climate warming on the distribution of the species is discussed.

Zebrus pallaoroi sp. nov.: a new species of goby (Actinopterygii: Gobiidae) from the Mediterranean Sea with a dna-based phylogenetic analysis of the Gobius-lineage

The gobies (Gobiidae) are the most diverse fish family in the Mediterranean Sea. Nevertheless, knowledge on their diversity, taxonomy, and phylogenetic relationships is still inadequate. The phylogenetic analyses reveal two genetically highly distinct clades among specimens identified as Zebrus zebrus. A new species, Zebrus pallaoroi sp. nov., is described based on an integrative approach. The neotype of Zebrus zebrus is designated. Genetic data confirm a pronounced level of divergence between Z. pallaoroi and Z. zebrus, with the mean genetic distance on cytochrome b being 18.1% and 1.07% on rhodopsin. Phylogenetic relationships within the Gobius-lineage were estimated on both markers. Morphologically, Z. pallaoroi is distinguished from the only congener Z. zebrus by having a snout longer than its eye, posterior nostril about 4/5–9/10 of the anterior nostril, eye diameter 4.3−4.7 in head length, ventrolateral head ridges transversally connected on the anterior side by a short transversal ridge, anterior membrane midline depth about 2/3 of the spinous ray, head canal pore α diameter about half of the distance between pore ρ and ρ1, suborbital sensory papillae row 5i going downwards to or near the level of row d, the distance between row 5i and row d absent or much smaller than the length of row 5i, and the body with ten to eleven vertical dark brown bands. Zebrus pallaoroi was recorded from the southern Adriatic, northern Ionian, and northern and western Aegean Seas, and is a cryptobenthic fish from very shallow waters.

Disentangling the evolutionary history of peri-Mediterranean cyprinids using host-specific gill monogeneans

The diversification of Mediterranean fish appears to be far more complex than could be explained by a single dispersion model. Cyprinids represent one of the most species-rich groups of freshwater fishes living in this region. The current distribution of several highly divergent cyprinid taxa is most likely the result of multiple dispersion events. Cyprinid fish serve as hosts for the highly diversified and host-specific monogenean parasites of the genus Dactylogyrus. On the assumption that the distribution of Dactylogyrus spp. reflects the biogeography and evolutionary history of their hosts, we used these parasites as an additional tool to shed new light on the evolutionary history of peri-Mediterranean cyprinids of the subfamily Barbinae. The degree of congruence between host and parasite phylogenies was investigated using 29 Dactylogyrus spp. and 34 Barbinae hosts belonging to the genera Aulopyge, Barbus and Luciobarbus. We showed that the morphological adaptation of Dactylogyrus (i.e. of the ventral bar, representing the most variable morphological character of the attachment organ) is linked with parasite phylogeny. By applying distance-based and event-based cophylogenetic approaches, we revealed a significant global coevolutionary signal. A total of 62% of individual host-parasite links contributed significantly to the coevolutionary structure evidenced between hosts of Barbus spp. and Iberian Luciobarbus spp., and their host-specific Dactylogyrus spp. The host switching of parasites was revealed as the most important coevolutionary event in the Dactylogyrus-Barbinae system in the peri-Mediterranean region. Cophylogenetic analyses and the mapping of the morphological character of the parasite attachment organ onto the phylogeny of Dactylogyrus indicate that endemic southern European Dactylogyrus spp. parasitizing cyprinids of Barbinae have multiple origins. We suggest that continental bridges connecting southern Europe and North Africa played a crucial role in the dispersion of cyprinids, affecting the distribution of their host-specific gill parasites.

Identification of past and present gobies: distinguishing Gobius and Pomatoschistus (Teleostei: Gobioidei) species using characters of otoliths, meristics and body morphometry

Gobies (Gobiidae + Oxudercidae) are among the largest groups of extant marine fishes. Fossils of gobies are abundant since the Miocene, and many species have been reported so far. However, delimitation of fossil goby species is challenging because molecular markers and diagnostic traits such as the disposition of sensory head papillae are lost. This study provides, for the first time, an actualistic framework for the identification of fossil goby species. We focus on characters that can in principle be recognized in fossils, and evaluate their ability to discriminate between extant goby species based on statistical analyses. Using 14 extant species of Gobius and seven species of Pomatoschistus, we conducted otolith morphometry, elliptic Fourier shape analysis of otoliths using the package ‘Momocs’, conventional fish morphometry, and meristic counts. In addition, the otoliths of all species are depicted based on SEM images and briefly described. Otolith Fourier shape analysis proved to be most efficient in discrimination of species within both genera, Gobius and Pomatoschistus. Several characters used in the other approaches also worked well, but the results were variable, and the relative taxonomic significance of particular variables tended to change depending on the species under consideration. We propose otolith shape analysis as a powerful tool to explore ancient goby species diversity when samples with abundant fossil otoliths are present. Overall, the herein presented data will greatly facilitate delimitation of fossil goby species in future studies, and will consequently shed new light on the evolution of goby diversity and biogeography through time.

Embryonic and larval development of the northern pike: An emerging fish model system for evo-devo research

The northern pike, Esox lucius, is one of the largest temperate freshwater apex predators with a characteristic morphology: an elongated body with pelvic, dorsal, and anal fins located at the rear as a functional feature to sprint predation. However, the typical pike character is its head, which is characterized by a long, flattened snout, a well-armed mouth with numerous teeth, and large eyes characteristic of shallow water visual predators. Although the northern pike is becoming increasingly popular as a model system for ecology and evolutionary research, a detailed staging table has not yet been reported. In this study, we report the first comprehensive staging table for the northern pike, spanning from the one-cell stage to the freely-swimming juvenile stage. In addition to classical embryological descriptions, we use a DAPI staining to distinguish individual cells and embryonic structures during the early development. This dataset, in combination with the genomic and transcriptomic resources already available, serves as a foundation for in-depth mechanistic studies dealing with development using this species.

High cryptic diversity of bitterling fish in the southern West Palearctic

South-east Europe, along with the adjacent region of south-west Asia, is an important biodiversity hotspot with high local endemism largely contributed by contemporary continental lineages that retreated to southern refugia during colder Quaternary periods. We investigated the genetic diversity of the European bitterling fish (Rhodeus amarus) species complex (Cyprinidae) across its range in the western Palearctic, but with a particular emphasis in the region of Balkan, Pontic and Caspian refugia. We genotyped 12 polymorphic microsatellite loci and a partial sequence of mitochondrial gene cytochrome b (CYTB) for a set of 1,038 individuals from 60 populations. We used mtDNA sequences to infer phylogenetic relationships and historical demography, and microsatellite markers to describe fine-scale genetic variability and structure. Our mtDNA analysis revealed six well-supported lineages, with limited local co-occurrence. Two lineages are distributed throughout central and western Europe (lineages "A" and "B"), with two zones of secondary contact. Another two lineages were restricted to the Ponto-Aegean region of Greece (lineages "C" and "D") and the final two lineages were restricted south of the Caucasus mountains (lineage "E" from the Black Sea watershed and lineage "F" from the Caspian watershed). A signal of recent expansion was revealed in the two widespread lineages and the Ponto-Aegean lineage "C". The geographic distribution of clusters detected by nuclear microsatellites corresponded well with mitochondrial lineages and demonstrated finely sub-structured populations. A profound population structure suggested a significant role of genetic drift in differentiation among lineages. Lineage divergence in the Ponto-Aegean and Caspian regions are substantial, supporting the validity of two described endemic species (Rhodeus meridionalis as lineage "D" and Rhodeus colchicus as lineage "E") and invite taxonomic evaluation of the other two southern lineages (Thracean "C" and Caspian "F").

The phylogenetic relationships and species richness of host-specific Dactylogyrus parasites shaped by the biogeography of Balkan cyprinids

Parasites exhibiting a high degree of host specificity are expected to be intimately associated with their hosts. Therefore, the evolution of host-specific parasites is at least partially shaped by the evolutionary history and distribution of such hosts. Gill ectoparasites of Dactylogyrus (Monogenea) are specific to cyprinid fish. In the present study, we investigated the evolutionary history of 47 Dactylogyrus species from the Balkan Peninsula, the Mediteranean region exhibiting the highest cyprinid diversity in Europe, and from central European cyprinids. Phylogenetic analyses revealed four well-supported clades of endemic and non-endemic Dactylogyrus spp. with four basal taxa. Endemic cyprinids with a limited distribution range were parasitized by endemic Dactylogyrus species, but some of them shared several Dactylogyrus species with central European cyprinids. Species delimitation analyses based on molecular data suggest that Dactylogyrus diversity is higher than that defined from morphology. Some endemic cyprinid species harboured Dactylogyrus species of different origins, this probably resulting from multiple host switching. Our results support the view that the evolution of Dactylogyrus in the Balkans has been influenced not only by the historical dispersion and distribution of their cyprinid hosts, but also by recent contacts of non-native cyprinid species with endemic cyprinid fauna in this region.

Phylogenetic relationships and classification of the Holarctic family Leuciscidae (Cypriniformes: Cyprinoidei)

The phylogenetic relationships and classification of the freshwater fish order Cypriniformes, like many other species-rich groups of vertebrates, has evolved over time with some consistency and inconsistencies of relationships across various studies. Within Cypriniformes, the Holarctic family Leuciscidae is one of the most widely distributed and highly diverse monophyletic groups of cyprinoids. Despite several studies conducted on this group, alternative hypotheses exist as to the composition and relationships within Leuciscidae. Here we assess the extent, composition, phylogenetic relationships, and taxonomy of this highly diverse group of fishes, using multiple mitochondrial and nuclear loci and a comprehensive and dense taxonomic sampling. Analyses of 418 specimens (410 species) resolve a well-supported Leuciscidae including 362 specimens (358 taxa) in six well-supported subfamilies/major clades: Pseudaspininae/Far East Asian clade (FEA); Laviniinae/North American Western clade (WC); Plagopterinae/North American Creek Chub-Plagopterin clade (CC-P); Leuciscinae/Eurasian Old World clade (OW) (minus Phoxinus) plus North American Notemigonus; Phoxininae/Eurasian Phoxinus clade (PHX); and Pogonichthyinae/North American clade (NA) including all remaining leuciscids. Within Leuciscidae, neither the traditional phoxinins (Phoxinus, FEA, Nearctic genera) nor all Nearctic genera (minus Notemigonus) are resolved as monophyletic; whereas the WC and CC-P form two independent lineages from remaining North American cyprinoids. A close relationship exists between Eurasian Phoxinus, NA, and OW clades, while FEA is the sister group to all remaining Leuciscidae. Major lineages resolved within these six subfamilies are mostly congruent with some previous studies. Our results suggests a complex evolutionary history of this diverse and widespread group of fishes.

Recent acute crayfish mortality reveals Aphanomyces astaci presence in Bosnia and Herzegovina

Although the introduction of the crayfish plague pathogen Aphanomyces astaci to Europe is responsible for substantial declines in native crayfish populations throughout the whole continent, its presence has never been officially confirmed in many European regions, including most of the Balkan Peninsula. We demonstrate that the recent crayfish mortality observed in Bosnia and Herzegovina (Mostarsko blato karst field, Neretva river drainage) was caused by A. astaci. The causative strain is known only from European crayfish, indicating that A. astaci poses a threat to native species in this region, even in the absence of its main vectors, the North American crayfish.

Ancient Mitochondrial Capture as Factor Promoting Mitonuclear Discordance in Freshwater Fishes: A Case Study in the Genus Squalius (Actinopterygii, Cyprinidae) in Greece

Hybridization and incomplete lineage sorting are common confounding factors in phylogeny and speciation resulting in mitonuclear disparity. Mitochondrial introgression, a particular case of hybridization, may, in extreme cases, lead to replacement of the mitochondrial genome of one species with that of another (mitochondrial capture). We investigated mitochondrial introgression involving two species of the cyprinid genus Squalius in the western Peloponnese region of Greece using molecular and morphological data. We found evidence of complete mitochondrial introgression of Squalius keadicus into two populations recognized as Squalius peloponensis from the Miras and Pamissos River basins and a divergence of mitochondrial genomes of S. keadicus from the Evrotas basin from that of the introgressed populations dating from the Pleistocene. Secondary contact among basins is a possible factor in connection of the species and the introgression event. Morphological analyses support the hypothesis of mitochondrial introgression, as S. keadicus was different from the other three populations recognized as S. peloponensis, although significant differences were found among the four populations. Isolation by geographical barriers arose during Pleistocene in the western Peloponnese were the source of the evolution of the two reciprocally monophyletic subclades found in the S. keadicus mitochondrial clade, and the morphological differences found among the four populations. Along with the lack of structure in the nuclear genome in the three populations ascribed to S. peloponensis, this suggests an incipient speciation process occurring in these Squalius species in the western Peloponnese.

A new species of Gobius (Perciformes: Gobiidae) from the Mediterranean Sea and the redescription of Gobius bucchichi

A new species of the gobiid genus Gobius (Gobiidae, Perciformes), Gobius incognitus sp. nov. is described from the Mediterranean Sea, and its most morphologically similar species Gobius bucchichi is redescribed. The new species is distinguished from its congeners by: scales in lateral series 51-59; predorsal scales 25-35; opercle scaled in adults with 10-16 scales present; pectoral fin with ray count 18-20 and free tips on upper rays well developed and on the first ray longer than two thirds of the entire ray length; pelvic disc complete and with well-developed anterior membrane without lateral lobes; anterior oculoscapular canal with pore α at rear of orbit; oculoscapular row x(1) not extending forwards to pore β; suborbital row d discontinuous with large gap below suborbital rows 3 and 4; eye diameter 1·08-1·32 in snout length; by pigment rows on cheek and pigmentation on pectoral-fin base.

Complete mitochondrial genome of the Greek nine-spined stickleback Pungitius hellenicus (Gasterosteiformes, Gasterosteidae)

The complete mitochondrial genome of the Greek nine-spined stickleback Pungitius hellenicus was obtained using Illumina high-throughput sequencing of genomic DNA. The genome was 16 713 bp long, and contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region. The arrangement of the genes was identical to that of other Gasterosteidae fishes. However, the control region of P. hellenicus contained three copies of imperfect repeated sequences (72–78 bp in single motifs), while P. pungitius and P. tymensis have one or two copies. Nucleotide identity between P. hellenicus and three other Pungitius species across all the 37 genic regions was 93.0% to 95.5%.

Complete mitochondrial genome of the Ukrainian nine-spined stickleback Pungitius platygaster (Gasterosteiformes, Gasterosteidae)

The complete mitochondrial genome of the Ukrainian nine-spined stickleback Pungitius platygaster was obtained using massive parallel sequencing of genomic DNA. The mitogenome sequence was 16 570 bp long, and the gene order and contents were identical to those of other sequenced Pungitius mitogenomes. In a phylogenetic analysis, the mitogenome of P. platygaster clustered with other Pungitius mitogenomes, yet being clearly distinct from those of P. pungitius, P. sinensis and P. kaibarae.

Different Histories, Different Destinies‒Impact of Evolutionary History and Population Genetic Structure on Extinction Risk of the Adriatic Spined Loaches (Genus Cobitis; Cypriniformes, Actinopterygii)

The region of Balkans is often considered as an ichthyologic "hot spot", with a great number of species and high portion of endemics living in fresh waters in a relatively small area. The Adriatic watershed in Croatia and Herzegovina is inhabited by six spined loach species (genus Cobitis) whose extinction risk estimations were based solely on their extent of occurrence (and/or area of occupancy) and its fragmentation, and conservation proposals do not consider diversity below species level. In this investigation we employed molecular genetic methods to describe present genetic structure of the Adriatic spined loaches and reveal their demographic history. The divergence of the Adriatic lineages inside the genus Cobitis started in Miocene and lasted until Pleistocene epoch. Geological events responsible for shaping recent diversity of spined loaches in the Adriatic basin are: the Dinarid Mountains upwelling, the evolution of Dinaric Lake system, local tectonic activity, river connections during glaciations and differences in sea level. Even though all the investigated species inhabit karstic rivers located in the same geographic area and that were subject of similar geological events, the results obtained reveal great differences in their genetic diversity and structure and point out the necessity of different conservation measures to ensure their future viability. High level of genetic polymorphism is characteristic for species located more to the south. Two species comprised of more than one population have completely different intraspecific structure; populations of C. illyrica are genetically distinct and represent separate evolutionary significant units, whereas intraspecific structure of C. narentana corresponds to metapopulational pattern. Without population genetic data, evolutionary significant units could be easily misidentified. Furthermore, the obtained results affirm that population genetic measurements are able to detect differences among closely located and related species and estimate extinction risk even more accurately than currently applied IUCN criteria.

Genetic and morphological variability of the European mudminnow Umbra krameri (Teleostei, Umbridae) in Serbia and in Bosnia and Herzegovina, a basis for future conservation activities

As a basis for future conservation activities, the genetic and external body morphology variability of the European mudminnow Umbra krameri, a highly endangered fish species in Serbia and in Bosnia and Herzegovina, was determined for existing populations with the use of molecular markers (mitochondrial and microsatellite DNA) and geometric morphometric methods. Mitochondrial DNA cytochrome b gene analysis revealed two previously undescribed haplotypes: Da1 (the Lugomir population from the Danube River basin) and Sa1 (the Bakreni Batar and the Gromiželj populations from the Sava River system), with a corresponding genetic distance of 0·7%. Paired values of FST and DAS distances for microsatellite marker data show that the difference between the Danube and the Sava populations is seven to nine times higher than the difference between the populations within the Sava River system. Geometric morphometric analyses also support a clear separation of the Lugomir population from the Bakreni Batar and the Gromiželj populations. The analysis of the body shape variation, however, indicates a significant difference between the two genetically indistinguishable Sava populations. The observed genetic and phenetic relationships of the analysed mudminnow populations most probably represent a consequence of historical, geographical and ecological factors. These results will offer guidelines for future protection, conservation and sustainable management of this species in the region.

Combining morphology and genetics in resolving taxonomy--a systematic revision of spined loaches (Genus Cobitis; Cypriniformes, Actinopterygii) in the Adriatic watershed

Taxonomic investigation of spined loaches from Dalmatia and Herzegovina was conducted on specimens from 14 localities. The results of the detailed morphological investigations were combined with genetic data (based on one mitochondrial and two nuclear genes) in order to resolve the taxonomic status of each Cobitis population. Among the investigated features of external morphology, the appearance of spots on the caudal fin base turned out to have the greatest diagnostic value. Furthermore, the number of branched fin rays enabled the discrimination of several species. No morphometric character alone could ensure determination of any Cobitis species. Nevertheless, groups of populations that are more similar in their body shapes correspond to mitochondrial phylogenetic lineages. Based on molecular genetic markers, Dalmatian and Herzegovinian spined loaches form independent lineages inside the Adriatic phylogenetic group. Mitochondrial DNA phylogenetic reconstruction revealed six monophyletic lineages, corresponding to six species distributed in the investigated area. The population distributed in Mostarsko blato karstic field in Bosnia and Herzegovina is described as a new species based on a unique combination of morphological characters: a single triangular Canestrini scale; usually 5¹/₂ branched anal fin rays, 6¹/₂ branched dorsal fin rays, 14 branched caudal fin rays; no spots in the surface pigmentation layer on the caudal fin base; scales on the body very small.