Milorad Mrakovčić

Phylogeography of isolated freshwater three-spined stickleback Gasterosteus aculeatus populations in the Adriatic Sea basin.

Analyses of mitochondrial (mt) DNA and microsatellite variation were carried out to examine the relationships between 10 freshwater populations of three-spined sticklebacks Gasterosteus aculeatus along the eastern coast of the Adriatic Sea. Partial sequences of the mtDNA control region and cytochrome b gene, in addition to 15 microsatellite loci, were used to analyse populations from four isolated river catchments. Results uncovered an Adriatic lineage that was clearly divergent from the European lineage, and confirmed that the most divergent and ancient populations are located within the Adriatic lineage as compared with other European populations. Two northern Adriatic populations formed independent clades within the European mitochondrial lineage, suggesting different colonization histories of the different Adriatic populations. Nuclear marker analyses also indicated deep divergence between Adriatic and European populations, albeit with some discordance between the mtDNA phylogeny of the northern Adriatic populations, further highlighting the strong differentiation among the Adriatic populations. The southern populations within the Adriatic lineage were further organized into distinct clades corresponding to respective river catchments and sub-clades corresponding to river tributaries, reflecting a high degree of population structuring within a small geographic region, concurrent with suggestions of existence of several microrefugia within the Balkan Peninsula. The highly divergent clades and haplotypes unique to the southern Adriatic populations further suggest, in accordance with an earlier, more limited survey, that southern Adriatic populations represent an important reservoir for ancient genetic diversity of G. aculeatus.

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.

Copepod communities in karstic mediterranean lakes along the eastern Adriatic coast

The copepod communities of karstic lakes along the eastern Adriatic coast were studied. Lakes were divided in several groups according to their morphology (deep, shallow, barrage and reservoirs), production (oligotrophic, mesotophic and eutrophic), and salinity of water: freshwater and brackish. Copidodiaptomus steueri, Eucyclops serrulatusand Macrocyclops albidus belong to the group that inhabited most of the lakes under the study, regardless of lake type. The shallow karstic lakes are usually inhabited by Thermocyclops dybowskii, T. oithonoides, Cyclops vicinus and Eudiaptomus padanus etruscus in freshwater biotopes, and Calanipedia aquaedulcis and Copidodiaptomus steueri in brackish biotopes. The last two species can also be found in deep karstic lakes with brackish water (Bacina lakes in the Neretva River delta). Species like Cyclops abyssorumcan be found in most deep freshwater lakes. Some Calanoida were recorded in only one lake, like Eudiaptomus transsylvanicusin the deep Lake Vrana on the island of Cres, or Eudiaptomus hadzici in the barrage Lake Visovac. Production of the lakes, expressed as copepod biomass, depends on lake trophy, and in some lakes also on hydrology and salinity. Most of the meso-eutrophic lakes in the study area had Calanoida dominating, while Cyclopoida dominated in some oligotrophic and eutrophic lakes as well.

Morphological comparison of bleaks (Alburnus, Cyprinidae) from the Adriatic Basin with the description of a new species

Abstract. The morphometric, meristic and phenotypical characters of the members of the genus Alburnus from the Adriatic Basin were analyzed on specimens from 11 localities, representing eight watersheds. The number of gill rakers, the number of lateral line scales, the number of branched anal fin rays and the coverage of the ventral keel by scales have the greatest significance in differentiating between species. Significant morphological differences exist between the Alburnus population from Lake Lugano (type locality for Alborella maxima Fatio, 1882) and all the remaining investigated populations. Alburnus from the Neretva River drainage is described as a new species and it is distinguished from other species of the genus Alburnus by the following combination of characters: 13½-15½ branched anal fin rays; 17–26 gill rakers; 40–48 lateral line scales; first anal fin ray below branched dorsal rays 6–10 or located up to one scale after the last dorsal fin ray; ventral keel exposed for at least ⅔ of a distance between the pelvic fin base and the anal aperture. The status of the Neretva River basin populations as a separate species was corroborated by genetic analyses, with p-distance between newly described species and A. arborella from the Zrmanja River 1.8–2.2%.

Ecologically acceptable flows definition for the Žrnovnica river (Croatia)

The paper defines an ecologically acceptable flow regime for the River Žrnovnica, Croatia. This is a small and relatively short karst river with high flows and high quality water, convenient for use for public water supply. Because the water from the river will be taken from the karst spring zone, the entire river channel could suffer negative ecological consequences. The main goal of setting minimum acceptable flows is to protect the Žrnovnica river food webs and to sustain the rare and endangered fish species Salmothymus obtusirostris. This paper presents results obtained from hydrological, morphological and biological investigations.

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.

A new endemic cyprinid species from the Danube drainage.

Populations of endemic Croatian dace were found to belong to two different species, one of which is first described in this study. Telestes karsticus sp. nov. differed morphologically from Telestes polylepis in the total count of lateral line scales, number of gill rakers and the shape of the posterior margin of the anal fin. Morphological differences were corroborated with mtDNA analyses (with p-distance between T. polylepis and T. karsticus sp. nov. ranging between 3·2 and 4·1%; and the number of substitutions between 37 and 47). The newly described species is geographically very localized. It has been recorded from only four localities around Velika Kapela and Mala Kapela mountains in Croatia.

The karyotype and NOR phenotype of Telestes ukliva (Cyprinidae)

Abstract. The karyotype and major ribosomal sites as revealed by silver staining and CMA3-fluorescence of Croatian leuciscine cyprinid endemic to Cetina River, Telestes ukliva were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs subtelocentric chromosomes. The largest chromosome pair of the complement was subtelocentric, which is a characteristic cytotaxonomic marker for all representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were detected in the telomeres of two pairs of mediumsized submetacentric chromosomes. Staining with CMA3 revealed four positive signals that corresponded to NOR sites. No heteromorphic sex chromosomes were found. The karyotype pattern of T. ukliva is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple NOR phenotype appears to be more derived as opposed to a uniform one NOR-bearing chromosome pair, ubiquitous in this group.

Sexual dimorphism of five Cobitis species (Cypriniformes, Actinopterygii) in the Adriatic watershed

Abstract. Morphological differences between female and male spined loaches belonging to five species from the Adriatic basin were examined. Besides the presence of the Canestrini scale and the length of the pectoral fins, sexual dimorphism is also visible in the position of the pectoral fins, as well as in the length of the pelvic fins. Both pectoral and pelvic fins are significantly longer in males than in females, whereas pectoral fins of females are located more anteriorly then in males. Differences in the length of pectoral and pelvic fins among species are also revealed. The role of the secondary sexual characters in males is probably connected with their special mating behaviour. Furthermore, a hypothesis that habitat conditions have greater impact on body dimensions of females than males is proposed.

FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA

The three-spined stickleback (Gasterosteus aculeatus Linaeus, 1758) is a small teleost fish considered to be one of the most widely distributed freshwater fishes in the world (Morrow, 2008). In the northern hemisphere, sticklebacks are absent only along the Arctic coasts of Siberia and North America (Mrakovcic et al., 2006). In Europe they often form highly abundant populations, and in some ecosystems are dominant (Clavero et al., 2009). Three-spined sticklebacks are listed as a species of Least Concern (LC) in the European IUCN Red List (Freyhof et al., 2008). However, freshwater populations in the Mediterranean region have experienced a sharp decline or even local extinction events (Clavero et al., 2009). Despite their wide global distribution, stickleback populations in Croatia are present in a fragmented distribution in isolated rivers of the Adriatic Basin: the Krka River (Visovac Lake), Neretva River catchment and Mirna River catchment on the Istrian peninsula (Mrakovcic et al., 2006; Zanella, 2009; Zanella et FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA