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

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.

Comparative mitogenome analyses uncover mitogenome features and phylogenetic implications of the subfamily Cobitinae

BACKGROUND

Loaches of Cobitinae, widely distributed in Eurasian continent, have high economic, ornamental and scientific value. However, the phylogeny of Cobitinae fishes within genera or family level remains complex and controversial. Up to now, about 60 Cobitinae mitogenomes had been deposited in GenBank, but their integrated characteristics were not elaborated.

RESULTS

In this study, we sequenced and analyzed the complete mitogenomes of a female Cobits macrostigma. Then we conducted a comparative mitogenome analysis and revealed the conserved and unique characteristics of 58 Cobitinae mitogenomes, including C. macrostigma. Cobitinae mitogenomes display highly conserved tRNA secondary structure, overlaps and non-coding intergenic spacers. In addition, distinct base compositions were observed among different genus and significantly negative linear correlation between AT% and AT-skew were found among Cobitinae, genus Cobitis and Pangio mitogenomes, respectively. A specific 3 bp insertion (GCA) in the atp8-atp6 overlap was identified as a unique feature of loaches, compared to other Cypriniformes fish. Additionally, all protein coding genes underwent a strong purifying selection. Phylogenetic analysis strongly supported the paraphyly of Cobitis and polyphyly of Misgurnus. The strict molecular clock predicted that Cobitinae might have split into northern and southern lineages in the late Eocene (42.11 Ma), furthermore, mtDNA introgression might occur (14.40 Ma) between ancestral species of Cobitis and ancestral species of Misgurnus.

CONCLUSIONS

The current study represents the first comparative mitogenomic and phylogenetic analyses within Cobitinae and provides new insights into the mitogenome features and evolution of fishes belonging to the cobitinae family.

Multilocus phylogenetic analysis helps to untangle the taxonomic puzzle of chubs (genus Squalius: Cypriniformes: Actinopteri) in the Adriatic basin of Croatia and Bosnia and Herzegovina

Fish of the genus Squalius inhabit various freshwater habitats across Europe and Asia, with a particularly high diversity in the Mediterranean area, but the taxonomic status of many populations is still a matter of debate. This study aims to resolve the taxonomic uncertainties of chubs distributed in the Adriatic basin of Croatia and Bosnia and Herzegovina. Phylogenetic reconstruction based on the mitochondrial gene for cytochrome b and two nuclear genes, the recombination activating gene 1 and the rhodopsin gene, reveal high diversity of chubs in the investigated area. Two evolutionary independent groups are revealed: the first comprising the species Squalius illyricus, S. microlepis, S. svallize, S. tenellus and S. zrmanjae, and a second group corresponding with S. squalus. Genetic distinctiveness of species belonging to different groups is high due to their divergence that began in the Middle Miocene. In addition to allopatric speciation as the main force of divergence of Adriatic Squalius species, several instances of natural hybridizations were detected, contributing to the observed diversity. A comparison of phylogenetic scenarios using Bayesian factors corroborated the molecular basis for recognition of six Squalius species in the Adriatic basin, while Squalius janae is confirmed to be a junior synonym of S. squalus.

Diversity of spined loaches from Asia Minor in a phylogenetic context (Teleostei: Cobitidae)

Accurate determination of species diversity in areas of high endemicity, particularly those lacking comprehensive systematic knowledge, represents a challenge for both taxonomists and conservationists. This need is particularly evident in areas greatly affected by anthropogenic disturbances such as the Eastern Mediterranean and its freshwater environments. To improve our knowledge of Eastern Mediterranean freshwater fishes, we phylogenetically studied Western Palearctic Cobitis species, focusing on those found in Turkey. Overall, our results provide a robust framework to assess the number of species of Cobitis. Phylogenetic reconstructions based on mitochondrial (cyt b) and nuclear (RAG1) sequences show seven major clades (Clades 1-7) grouping all Western Palearctic Cobitis species, except C. melanoleuca. In general, each major clade comprises Cobitis species that inhabit geographically close areas and have similar secondary sexual characters. Multiple divergent lineages were identified in our analyses, some of which were highly divergent such as the ones inhabiting Turkish freshwaters. Moreover, in some analyses, several of the identified lineages were incongruent with a priori defined species. Furthermore, our analyses identified eight potentially new candidate species, six that had been suggested in previous studies and two that are reported here for the first time. Our results reveal Turkey as the area with the greatest diversity of spined loaches in the Mediterranean.

Ancient connections among the European rivers and watersheds revealed from the evolutionary history of the genus Telestes (Actinopterygii; Cypriniformes)

In order to better understand the complex geologic history of the Mediterranean area, we have analysed evolutionary history, phylogeographic structure and molecular diversity of freshwater fishes belonging to the genus Telestes. As primary freshwater fishes distributed largely in the Mediterranean basin, this genus represents a suitable model system for investigating the historical biogeography of freshwater drainage systems in southern Europe. In this investigation we have included samples representing all Telestes species and based our analyses on one mitochondrial and one nuclear gene. We have investigated phylogenetic structure inside the genus Telestes, estimated divergence times, reconstructed ancestral distribution ranges and described intraspecific molecular diversity. Diversification of Telestes started in the Early Miocene, when the ancestors of T. souffia, lineage comprising T. croaticus and T. fontinalis, and the one comprising T. pleurobipunctatus and T. beoticus got isolated. The remaining species are genetically more closely related and form a common cluster in the recovered phylogenetic trees. Complex geological history of southern Europe, including formation of continental bridges, fragmentation of landmass, closing of the sea corridor, local tectonic activities, led to complicated biogeographical pattern of this genus, caused by multiple colonization events and passovers between ancient rivers and water basins. Especially pronounced diversity of Telestes found in the Adriatic watershed in Croatia and Bosnia and Herzegovina is a consequence of a triple colonization of this area by different lineages, which led to an existence of genetically distinct species in neighboring areas. Significant intraspecific structuring is present in T. souffia, T. muticellus, T. croaticus and T. pleurobipunctatus. Besides in well-structured species, elevated levels of genetic polymorphism were found inside T. turskyi and T. ukliva, as a consequence of their old origin and unconstrained evolutionary history.

Karyosystematics and molecular taxonomy of the anomalous blue butterflies (Lepidoptera, Lycaenidae) from the Balkan Peninsula

The Balkan Peninsula represents one of the hottest biodiversity spots in Europe. However, the invertebrate fauna of this region is still insufficiently investigated, even in respect of such well-studied organisms as Lepidoptera. Here we use a combination of chromosomal, molecular and morphological markers to rearrange the group of so-called anomalous blue butterflies (also known as 'brown complex' of the subgenus Agrodiaetus Hübner, [1822] and as the Polyommatus (Agrodiaetus) admetus (Esper, 1783) species group) and to reveal its cryptic taxonomic structure. We demonstrate that Polyommatus aroaniensis (Brown, 1976) is not as widespread in the Balkans as was previously thought. In fact, it has a dot-like distribution range restricted to the Peloponnese Peninsula in South Greece. Polyommatus orphicus Kolev, 2005 is not as closely related to the Turkish species Polyommatus dantchenkoi (Lukhtanov & Wiemers, 2003) as was supposed earlier. Instead, it is a Balkan endemic represented by two subspecies: Polyommatus orphicus orphicus (Bulgaria) and Polyommatus orphicus eleniae Coutsis & De Prins, 2005 (Northern Greece). Polyommatus ripartii (Freyer, 1830) is represented in the Balkans by an endemic subspecies Polyommatus ripartii pelopi. The traditionally recognized Polyommatus admetus (Esper, 1783) is shown to be a heterogeneous complex and is divided into Polyommatus admetus sensu stricto (the Balkans and west Turkey) and Polyommatus yeranyani (Dantchenko & Lukhtanov, 2005) (east Turkey, Armenia, Azerbaijan and Iran). Polyommatus nephohiptamenos (Brown & Coutsis, 1978) is confirmed to be a species with a dot-like distribution range in Northern Greece. Finally, from Central Greece (Timfristos and Parnassos mountains) we describe Polyommatus timfristos Lukhtanov, Vishnevskaya & Shapoval, sp. n. which differs by its haploid chromosome number (n=38) from the closely related and morphologically similar Polyommatus aroaniensis (n=47-48) and Polyommatus orphicus (n=41-42). We provide chromosomal evidence for three separate south Balkan Pleistocene refugia (Peloponnesse, Central Greece and Northern Greece/South Bulgaria) and stress the biogeographic importance of Central Greece as a place of diversification. Then we argue that the data obtained have direct implications for butterfly karyology, taxonomy, biogeography and conservation.