Molecular data suggest a multispecies complex of Phoxinus (Cyprinidae) in the Western Balkan Peninsula.

This study aimed to evaluate the phylogeographic distribution of Phoxinus phoxinus sensu lato populations in the Balkan Peninsula using molecular methods. For the western Balkan Peninsula, two species (Danubian P. phoxinus and Adriatic P. lumaireul) have been suggested, but not confirmed by subsequent morphological studies or by genetic data. For the present study, more than 300 specimens were collected from the western Balkans. A partial sequence of the mt cyt b gene analysed using Bayesian and ML methods revealed several well-supported clades, with distances ranging from 4% to 11%. The clades were corroborated by RAG1 sequence analysis. Thus, the molecular analysis points to a multispecies complex of Phoxinus sp. with ranges of the clades extending north-west to south-east along the western Balkan Peninsula. In addition, the dispersion of fish through subterranean water connections in karst is indicated.

Molecular phylogeny of Salmo of the western Balkans, based upon multiple nuclear loci.

BACKGROUND: Classification of species within the genus Salmo is still a matter of discussion due to their high level of diversity and to the low power of resolution of mitochondrial (mt)DNA-based phylogeny analyses that have been traditionally used in evolutionary studies of the genus. We apply a new marker system based on nuclear (n)DNA loci to present a novel view of the phylogeny of Salmo representatives and we compare it with the mtDNA-based phylogeny. METHODS: Twenty-two nDNA loci were sequenced for 76 individuals of the brown trout complex: Salmo trutta (Danubian, Atlantic, Adriatic, Mediterranean and Duero mtDNA lineages), Salmo marmoratus (marble trout), Salmo obtusirostris (softmouth trout), and Salmo ohridanus (Ohrid belvica or belushka). Sequences were phylogenetically analyzed using maximum-likelihood and Bayesian Inference methods. The divergence time of the major clades was estimated using the program BEAST. RESULTS: The existence of five genetic units i.e. S. salar, S. ohridanus, S. obtusirostris, S. marmoratus and the S. trutta complex, including its major phylogenetic lineages was confirmed. Contrary to previous observations, S. obtusirostris was found to be sister to the S. trutta complex and the S. marmoratus clade rather than to the S. ohridanus clade. Reticulate evolution of S. obtusirostris was confirmed and a time for its pre-glacial origin suggested. S. marmoratus was found to be a separate species as S. trutta and S. obtusirostris. Relationships among lineages within the S. trutta complex were weakly supported and remain largely unresolved. CONCLUSIONS: Nuclear DNA-based results showed a fairly good match with the phylogeny of Salmo inferred from mtDNA analyses. The comparison of nDNA and mtDNA data revealed at least four cases of mitochondrial-nuclear DNA discordance observed that were all confined to the Adriatic basin of the Western Balkans. Together with the well-known extensive morphological and genetic variability of Balkan trouts, this observation highlights an interesting and variegated evolutionary history of Salmo in this area.

Fish migrate underground: the example of Delminichthys adspersus (Cyprinidae).

Complex aquatic systems of karst harbour a rich but little-investigated biodiversity. In Croatia and Bosnia-Herzegovina karst, temporal springs are inhabited by a group of minnow-like fishes that retreat to the associated ground water during dry seasons and spend several months underground. The most abundant species in this group is Delminichthys adspersus (Heckel 1843), which also has the most fragmented distribution range. To determine the population composition and dispersal patterns, and to detect potential underground migration, a large genetic data set comprising 544 specimens of D. adspersus covering most of its distribution area was analysed. Analysis of mitochondrial cytochrome b sequences (∼1000 bp) and eight microsatellite loci showed that D. adspersus comprises at least three subpopulations with gene flow occurring among them. Coalescent-based analysis revealed a complex migration pattern, with several unidirectional dispersal paths, including between temporal springs that share no surface connection. The results of this study suggest the existence of recurrent underground migration of fish in a karst environment and demonstrate the complexity of its hydrological network. The findings are relevant to conservation strategies for endemic karst organisms and karst ecosystems as a whole.

The minnow Phoxinus lumaireul (Leuciscidae) shifts the Adriatic-Black Sea basin divide in the north-western Dinaric Karst region.

Karst landscapes are characterized by intermittent and sinking streams. The most common method used to study underground hydrological connections in karst is tracing tests. However, a more biologically oriented approach has been suggested: analysis of the genetic structure of aquatic organisms. Biological tracers can be sought among trogloxenes, that is, surface species that occasionally enter caves and groundwater. One such example is the fish genus Phoxinus, which exhibits high genetic diversity and complex phylogeography in the Balkan Peninsula. In the north-western Dinaric Karst, the complex hydrological network was digitalized in 2020. Contemporaneously, Phoxinus lumaireul populations in the Slovenian Dinaric Karst were intensively sampled and analysed for fragments of two mitochondrial genes and one nuclear gene. The derived phylogeographic structure and data on hydrological connections were compared to evaluate support for three alternative scenarios: The genetic structure (1) is a consequence of the ongoing geneflow through underground connections, (2) reflects a previous hydrological network or (3) is an outcome of anthropogenic translocations. The results suggest that the first two scenarios seem to have played a major role, while the third has not had profound effects on the genetic composition. Comparison between the genetic structure of Slovenian Dinaric Karst sampling sites and that of hydrologically isolated reference sampling sites indicated a greater genetic connectivity in the former. Moreover, the range of Adriatic (1a) and Black Sea (1c) haplotypes does not correspond to the Adriatic-Black Sea basin divide but is shifted northwards.

How Can We Advance Integrative Biology Research in Animal Science in 21st Century? Experience at University of Ljubljana from 2002 to 2022.

In this perspective analysis, we strive to answer the following question: how can we advance integrative biology research in the 21st century with lessons from animal science? At the University of Ljubljana, Biotechnical Faculty, Department of Animal Science, we share here our three lessons learned in the two decades from 2002 to 2022 that we believe could inform integrative biology, systems science, and animal science scholarship in other countries and geographies. Cultivating multiomics knowledge through a conceptual lens of integrative biology is crucial for life sciences research that can stand the test of diverse biological, clinical, and ecological contexts. Moreover, in an era of the current COVID-19 pandemic, animal nutrition and animal science, and the study of their interactions with human health (and vice versa) through integrative biology approaches hold enormous prospects and significance for systems medicine and ecosystem health.

Phylogeographic structure and demographic patterns of brown trout in North-West Africa.

The objectives of the study were to determine the phylogeographic structure of brown trout (Salmo trutta) in Morocco, elucidate their colonization patterns in North-West Africa and identify the mtDNA lineages involved in this process. We also aimed to resolve whether certain brown trout entities are also genetically distinct. Sixty-two brown trout from eleven locations across the Mediterranean and the Atlantic drainages in Morocco were surveyed using sequence analysis of the mtDNA control region and nuclear gene LDH, and by genotyping twelve microsatellite loci. Our study confirms that in Morocco both the Atlantic and Mediterranean basins are populated by Atlantic mtDNA lineage brown trout only, demonstrating that the Atlantic lineage (especially its southern clade) invaded initially not only the western part of the Mediterranean basin in Morocco but also expanded deep into the central area. Atlantic haplotypes identified here sort into three distinct groups suggesting Morocco was colonized in at least three successive waves (1.2, 0.4 and 0.2-0.1 MY ago). This notion becomes more pronounced with the finding of a distinct haplotype in the Dades river system, whose origin appears to coalesce with the nascent stage of the basal mtDNA evolutionary lineages of brown trout. According to our results, Salmo akairos, Salmo pellegrini and "green trout" from Lake Isli do not exhibited any character states that distinctively separate them from the other brown trout populations studied. Therefore, their status as distinct species was not confirmed.

Neotype designation for Thymallus aeliani Valenciennes, 1848 from a museum topotype specimen and its affiliation with Adriatic grayling on the basis of mitochondrial DNA.

In 1848, the grayling Thymallus aeliani (Valenciennes) was described from Lake Maggiore, Italy, in the north Adriatic basin. Genetic analyses of the mitochondrial control region showed a unique evolutionary history of grayling inhabiting the rivers of northern Adriatic basin, from the upper reaches of the Po River and its left tributaries in the west to the Soca River in the east, which resulted in the designation of this phylogenetic lineage as Adriatic grayling. Consequently, the name T. aeliani was connected to the Adriatic lineage, re-establishing the validity of this taxon. However, the mitochondrial haplotypes belonging to Adriatic grayling were never compared with the type specimens of T. aeliani, as their whereabouts were unknown. In this study, a neotype for T. aeliani was designated using topotypical specimens stored at the Natural History Museum in Vienna. The neotype (NMW 68027:2 labelled as "Lago Maggiore, Bellotti, 1880") was designated pursuant to the conditions stipulated in Article 75.3 of the International Code of Zoological Nomenclature. Furthermore, the mitochondrial control region of the neotype was compared to haplotypes of the Adriatic lineage and showed high genetic similarity, which therefore connects the species name T. aeliani to the Adriatic grayling. This crucial step in fixing nomenclatural status of this species is very important for its protection and management.

Genetic architecture of trout from Albania as revealed by mtDNA control region variation.

To determine the genetic architecture of trout in Albania, 87 individuals were collected from 19 riverine and lacustrine sites in Albania, FYROM and Greece. All individuals were analyzed for sequence variation in the mtDNA control region. Among fourteen haplotypes detected, four previously unpublished haplotypes, bearing a close relationship to haplotypes of the Adriatic and marmoratus lineages of Salmo trutta, were revealed. Ten previously described haplotypes, characteristic of S. ohridanus, S. letnica and the Adriatic and Mediterranean lineages of S. trutta, were also detected. Haplotypes detected in this study were placed in a well supported branch of S. ohridanus, and a cluster of Mediterranean-Adriatic-marmoratus haplotypes, which were further delimited into three subdivisions of Mediterranean, marmoratus, and a previously non-described formation of four Adriatic haplotypes (Balkan cluster). Haplotypes of the Balkan cluster and the other Adriatic haplotypes, do not represent a contiguous haplotype lineage and appear not to be closely related, indicating independent arrivals into the Adriatic drainage and suggesting successive colonization events. Despite the presence of marmoratus haplotypes in Albania, no marbled phenotype was found, confirming previously reported findings that there is no association between this phenotype and marmoratus haplotypes.

Environmental DNA in subterranean biology: range extension and taxonomic implications for Proteus.

Europe's obligate cave-dwelling amphibian Proteus anguinus inhabits subterranean waters of the north-western Balkan Peninsula. Because only fragments of its habitat are accessible to humans, this endangered salamander's exact distribution has been difficult to establish. Here we introduce a quantitative real time polymerase chain reaction-based environmental DNA (eDNA) approach to detect the presence of Proteus using water samples collected from karst springs, wells or caves. In a survey conducted along the southern limit of its known range, we established a likely presence of Proteus at seven new sites, extending its range to Montenegro. Next, using specific molecular probes to discriminate the rare black morph of Proteus from the closely related white morph, we detected its eDNA at five new sites, thus more than doubling the known number of sites. In one of these we found both black and white Proteus eDNA together. This finding suggests that the two morphs may live in contact with each other in the same body of groundwater and that they may be reproductively isolated species. Our results show that the eDNA approach is suitable and efficient in addressing questions in biogeography, evolution, taxonomy and conservation of the cryptic subterranean fauna.

Experience from Lipizzan horse and salmonid species endemic to the Adriatic river system. Examples for the application of molecular markers for preservation of biodiversity and management of animal genetic resources.

Management of breeding- and free-living populations, traditionally based on phenotypic traits, relays more and more on availability of reliable information about the basic population genetic parameters as heterozygosity, mean number of alleles per locus, percentage of polymorphic loci, population structuring, genetic distances and others. Therefore, the application of molecular markers, revealing a great deal of phenotypically hidden information, becomes inevitable for population analysis. Conservation geneticists use this information for implementation of appropriate management policies. Application of molecular markers in Lipizzan horse breed, which is an example for a pedigreed breeding population, and in two endangered salmonid fish populations in Slovenia, are presented. In the Lipizzan horse breed, an insight in the population structure, overall heterozygosity, relationship between population parameters and phenotypic traits and reliability of pedigree data was gained by using molecular markers. Marble trout and Adriatic grayling were selected as examples for free-living populations, seriously endangered by human activity in the past. Development of informative molecular markers, their application and suggestions for appropriate conservation actions are described.

Historical demography of brown trout (Salmo trutta) in the Adriatic drainage including the putative S. letnica endemic to Lake Ohrid.

We explore the historical demography of the Adriatic lineage of brown trout and more explicitly the colonization and phylogenetic placement of Ohrid trout, based on variation at 12 microsatellite loci and the mtDNA control region. All Adriatic basin haplotypes reside in derived positions in a network that represents the entire lineage. The central presumably most ancestral haplotype in this network is restricted to the Iberian Peninsula, where it is very common, supporting a Western Mediterranean origin for the lineage. The expansion statistic R2, Bayesian based estimates of demographic parameters, and star-like genealogies support expansions on several geographic scales, whereas application of pairwise mismatch analysis was somewhat ambiguous. The estimated time since expansion (155,000 years ago) for the Adriatic lineage was supported by a narrow confidence interval compared to previous studies. Based on microsatellite and mtDNA sequence variation, the endemic Ohrid trout represents a monophyletic lineage isolated from other Adriatic basin populations, but nonetheless most likely evolving from within the Adriatic lineage of brown trout. Our results do not support the existence of population structuring within Lake Ohrid, even though samples included two putative intra-lacustrine forms. In the interests of protecting the unique biodiversity of this ancient ecosystem, we recommend retaining the taxonomic epithet Salmo letnica for the endemic Ohrid trout.

Phylogeographic study of brown trout from Serbia, based on mitochondrial DNA control region analysis.

In order to illuminate the phylogeography of brown trout (Salmo trutta) populations in the Balkan state of Serbia, the 561 bp 5'-end of mtDNA control region of 101 individuals originating from upland tributaries of the Danubian, Aegean and Adriatic drainages were sequenced and compared to corresponding brown trout sequences obtained in previous studies. Among 15 haplotypes found, 14 were considered native, representing the Danubian and Adriatic lineages of the brown trout, while one haplotype (ATcs1), found only in two individuals originating from two stocked rivers, corresponded to the Atlantic lineage and was considered introduced. Native haplotypes exhibited a strong geographic pattern of distribution: the Danubian haplotypes were strictly confined to the Danubian drainage, while the Adriatic haplotypes dominated in the Aegean and Adriatic drainages; most of the total molecular variance (69%) was attributed to differences among the drainages. Phylogenetic reconstruction, supplemented with seven haplotypes newly described in this study, suggested a sister position of the Atlantic-Danubian and Adriatic-Mediterranean-marmoratus ("southern") phylogenetic group, and pointed to the existence of a distinct clade, detected within the "southern" group. The data obtained confirmed our expectation of the existence of high genetic diversity in Balkan trout populations, and we recommend more widespread surveys covering trout stocks from the region.