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In this article, we provide an updated list of freshwater fishes in Albania for each sub-basin. The distribution data and taxa-lists presented are based on a literature review up to October 2022 and intensive fieldwork conducted in the last 15 years. Distributional records of 101 fish species (deriving from 25 families) in 11 different sub-basins are reported. There are new records that include native, alien and translocated fish species. The distinctiveness of Albanian freshwater fishes is highlighted while defining a specific ichthyological region for the whole Balkan region. The freshwater fish fauna of Albania represents a special value of the national heritage, especially due to its diversity and a high degree of endemicity. This is mainly due to the complex geological and climatic conditions, and the location between the Adriatic and Ionian Seas on the west and the continental areas of the Balkans on the other side, which have allowed different colonization from outside the area and long periods of speciation. Eleven hydrographic basin units are analyzed for species composition, evolutionary patterns, and ecological features. This review brings the number of Albanian freshwater fish taxa to 101, with 20 species added from the previous 1995 inventory and several species deleted due to taxonomic changes.

In the inland waters of the Balkans, many brown trout populations have been severely depleted. Therefore, identifying potential threats to their continued survival and ranking populations based on their biological and evolutionary importance enables setting conservation priorities. To assess the sustainability of the brown trout populations in the territory of Serbia (central Balkans), a modification of the ESHIPPO model was performed. The main modification involves incorporating the investigated populations' genetic structure into the model. Therefore, the new ESHIPPOsalmo model includes an analysis of biological parameters and the impact of multiple factors, including habitat alterations, invasive species, pollution, human population growth, and over-exploitation. In order to investigate individual levels of influence of the model's analyzed parameters, a combination of supervised and unsupervised machine learning methods was used. The structure of the model is based on general and easily measurable indicators, which enables its application in any salmonid river in the world. By evaluating the parameters of the ESHIPPOsalmo model, we were able to establish that, of the analyzed populations from 46 localities, 37% have a moderate level of sustainability, 43% low, and 20% critically low. [ABSTRACT FROM AUTHOR]

Artificial propagation and stocking of brown trout is a standard practice in recreational fishery management. In recent decades, the importance of maintaining intraspecific diversity and protecting locally adapted lineages has been recognized for the species' long-term survival. The first step in selecting donors for stocking involves distinguishing native trout from non-native and introgressed individuals. The established method for discerning Atlantic hatchery strains from the wild populations involves genetic screening of individual diagnostic SNPs and microsatellite assignment tests. This study, using Serbia's Panjica hatchery as an example, illustrates the proper conduct of routine genetic screening for identifying suitable donors for supportive stocking. The broodstock and reference populations were screened using mtDNA control region, LDH nuclear gene, and 12 microsatellite loci to assess the origin, diversity, and inbreeding levels. The analysis revealed only moderate contamination with Atlantic trout and showed the regional origin of the Danubian genes – over 50% of the broodstock was composed of non-introgressed Danubian individuals tracing their origin to the Zapadna Morava River system. Additionally, the study highlighted a considerable discordance between LDH locus and microsatellites in identifying introgressed individuals, raising concerns about the sole reliance on LDH locus for the identification of Atlantic genetic origin in nuclear DNA.

This article presents new findings on the fish species Pomatoschistus nanus in the Mediterranean Sea. The species has been identified through various analyses and has been found in new locations such as Malta and Cyprus, expanding its known distribution. The article provides detailed information on the physical characteristics and identification of the species. However, the study also highlights the need for further research to fully understand the species' morphological diversity. [Extracted from the article]

Despite being one of the most speciose fish families in the Mediterranean Sea, knowledge about the diversity of gobies (Actinopterygii: Gobiidae) in this sea is still unsatisfactory, as documented by recent descriptions of a number of new species. Although very common in shallow water, Gobius incognitus Kovačić & Šanda, 2016, had escaped attention until 2016, when it was discovered. Due to its overall superficial morphological similarity, G. incognitus used to be confused with a much rarer species, Gobius bucchichi Steindachner, 1870, which was considered one of the most common shallow-water gobies in the Mediterranean Sea. In this work, we tested the suitability of the genetic data (mitochondrial gene encoding cytochrome b) for identifying and distinguishing between these two goby species, and assessed the congruency between the distribution records based on genetic data and those based on morphological identification. We analysed material of 304 specimens of G. incognitus and G. bucchichi from 49 localities covering a considerable part of the Mediterranean Sea, Black Sea, and the Atlantic Ocean near Gibraltar, representing 19 geographically well-separated areas. We detected 270 sequences of G. incognitus, and only 34 of G. bucchichi. In both species, a high haplotype variability was observed. The sequence species identity matched morphological identification for all specimens for which vouchers were available. The mean uncorrected p-distance between G. incognitus and G. bucchichi was 13%, while the mean intraspecific distances were much lower (0.63% and 0.68%, respectively). We found 79 fixed mutations between these two species. Data on distribution based on genetic identification are completely congruent with published results based on morphological identification. The results of this study support molecular methods as a reliable tool for distinguishing morphologically similar fish species, which is particularly useful when only tissue is available for determination. [ABSTRACT FROM AUTHOR]

Sabanejewia romanica was recorded for the first time on the territory of Serbia in three direct tributaries of the Danube River (Rečka River, Slatinska River and Zamna River). This is the first record of the species outside Romania, the westernmost point of its occurrence and the first verified record of the species from the right tributaries of the Danube River. Genetic characterisation of the Serbian specimens showed that they are the most related to the Romanian S. romanica, with a high recorded net evolutionary divergence between them. Further studies with included populations from the whole geographical range of S. romanica should provide an accurate picture of genetic diversity and phylogenetic relations within the species. [ABSTRACT FROM AUTHOR]

During their radiation, certain groups of animals evolved significant phenotypic disparity (morphological diversity), enabling them to thrive in diverse environments. Adaptations to the same type of environment can lead to convergent evolution in function and morphology. However, well-documented examples in repeated adaptations of teleost fishes to different habitats, which are not primarily related to trophic specialization, are still scarce. Gobies are a remarkable fish group, exhibiting a great species diversity, morphological variability, and extraordinary ability to colonize very different environments. A variety of lifestyles and body forms evolved also in European lineages of gobies. We conducted two-dimensional geometric morphometric and phylomorphospace analyses in European lineages of gobies and evaluated the extent of convergent evolution in shape associated with adaptation to various habitats. Our analyses revealed the change in shape along the nektonic-cryptobenthic axis, from very slender head and body to stout body and wide head. We showed convergent evolution related to mode of locomotion in the given habitat in four ecological groups: nektonic, hyperbenthic, cryptobenthic and freshwater gobies. Gobies, therefore, emerge as a highly diversified lineage with unique lifestyle variations, offering invaluable insights into filling of ecomorphological space and mechanisms of adaptation to various aquatic environments with distinct locomotion requirements., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE).)