The freshwaters of Iraq harbour a high diversity of endemic and phylogenetically unique species. One of the most diversified fish groups in this region is cyprinoids, and although their distribution is relatively well known, their monogenean parasites have only rarely been investigated. Herein, we applied an integrative approach, combining morphology with molecular data, to assess the diversity and phylogeny of cyprinoid-associated monogenean parasites. A total of 33 monogenean species were collected and identified from 13 endemic cyprinoid species. The highest species diversity was recorded for Dactylogyrus (Dactylogyridae, 16 species) and Gyrodactylus (Gyrodactylidae, 12 species). Four species of Dactylogyrus and 12 species of Gyrodactylus were identified as new to science and described. Two other genera, Dogielius (Dactylogyridae) and Paradiplozoon (Diplozoidae), were represented only by 4 and 1 species, respectively. Phylogenetic analyses of the Dactylogyrus and Gyrodactylus species revealed that the local congeners do not form a monophyletic group and are phylogenetically closely related to species from other regions (i.e. Europe, North Africa and Eastern Asia). These findings support the assumption that the Middle East served as an important historical crossroads for the interchange of fauna between these 3 geographic regions.

• Keywords
• Cyprinoidei, Dactylogyrus, Dogielius, Gyrodactylus, Middle East, Paradiplozoon, phylogeny, species diversity,
• MeSH
• Phylogeny MeSH
• Fishes MeSH
• Trematoda * genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Iraq epidemiology   MeSH
• Africa, Northern MeSH
• Middle East MeSH

Approaches using microsatellite markers are considered the gold standard for modern population genetic studies. However, although they have found application in research into various platyhelminth taxa, they remained substantially underutilized in the study of monogeneans. In the present study, a newly developed set of 24 microsatellite markers was used to investigate the genetic diversity of the generalist monogenean species Dactylogyrus vistulae. The analyzed parasite specimens were collected from 13 cyprinoid species from 11 sites in the Apennine and Balkan peninsulas. A total of 159 specimens were genotyped at each of the loci and the number of alleles per locus ranged from 2 to 16, with a mean number of 6.958 alleles per locus. Exceptionally high genetic diversity was observed among D. vistulae individuals in the southern Balkans (mean N A per locus = 3.917), suggesting that generalist D. vistulae expanded from the south to the north in the Balkans and later into central Europe. The initial clustering analysis divided all investigated specimens into three major clusters; however, the results of the subsequent analyses revealed the existence of various subpopulations, suggesting that the population structure of D. vistulae is associated with the diversification of their cyprinoid hosts. In addition, the partition of the parasite population was observed in regions of the sympatric occurrence of two host species, indicating that these hosts may represent a barrier for gene flow, even for generalist parasite species.

• Keywords
• Cyprinoidei, historical dispersion, host‐specific parasites, polymorphic markers, population genetics,
• Publication type
• Journal Article MeSH

The epicontinental fauna of the Iberian Peninsula is strongly influenced by its geographical history. As the possibilities for dispersion of organisms into and from this region were (and still are) limited, the local fauna consists almost exclusively of endemic species. Almost all Iberian freshwater fishes of the families Leuciscidae and Cyprinidae are endemic and on-going research on these taxa continually uncovers new species. Nevertheless, information on their host-specific parasites remains scarce. In this study, we investigate the diversity and phylogenetic relationships in monogeneans of the genus Dactylogyrus (gill ectoparasites specific to cyprinoid fish) in the Iberian Peninsula. Twenty-two species were collected and identified from 19 host species belonging to Cyprinidae and Leuciscidae. A high degree of endemism was observed, with 21 Dactylogyrus species reported from Iberia only and a single species, D. borealis, also reported from other European regions. Phylogenetic analysis split the endemic Iberian Dactylogyrus into two well-supported clades, the first encompassing Dactylogyrus parasitizing endemic Luciobarbus spp. only, and the second including all Dactylogyrus species of endemic leuciscids and four species of endemic cyprinids. Species delimitation analysis suggests a remarkable diversity and existence of a multitude of cryptic Dactylogyrus species parasitizing endemic leuciscids (Squalius spp. and representatives of Chondrostoma s.l.). These results suggest a rapid adaptive radiation of Dactylogyrus in this geographically isolated region, closely associated with their cyprinoid hosts. Moreover, phylogenetic analysis supports that Dactylogyrus parasites colonized the Iberian Peninsula through multiple dispersion events.

• Keywords
• Cyprinoidea, Iberian Peninsula, Monogenea, host-specificity, phylogeny, species delimitation,
• MeSH
• Biodiversity MeSH
• Adaptation, Biological MeSH
• Biological Evolution * MeSH
• Cyprinidae * MeSH
• Trematode Infections parasitology   veterinary   MeSH
• Fish Diseases parasitology   MeSH
• Trematoda physiology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Portugal MeSH
• Spain MeSH

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.

• MeSH
• Biodiversity * MeSH
• Cyprinidae parasitology   MeSH
• Phylogeny * MeSH
• Host Specificity * MeSH
• Evolution, Molecular MeSH
• Platyhelminths classification   genetics   isolation & purification   MeSH
• Gills parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Balkan Peninsula MeSH
• Mediterranean Region MeSH

The genes of major histocompatibility complex (MHC) provide an excellent opportunity to study host-parasite relationships because they are expected to evolve in response to parasites and variation in parasite communities. In this study, we investigated the potential role of parasite-mediated selection acting on MHC class IIB (DAB) genes in European chub (Squalius cephalus) natural populations. We found significant differences between populations in metazoan parasites, neutral and adaptive genetic diversities. The analyses based on pairwise data revealed that populations with dissimilar MHC allelic profiles were geographically distant populations with significantly different diversity in microsatellites and a dissimilar composition of parasite communities. The results from the generalized estimating equations method (GEE) on the level of individuals revealed that metazoan parasite load in European chub was influenced by the diversity of DAB alleles as well as by the diversity of neutral genetic markers and host traits reflecting condition and immunocompetence. The multivariate co-inertia analysis showed specific associations between DAB alleles and parasite species. DAB1-like alleles were more involved in associations with ectoparasites, while DAB3-like alleles were positively associated with endoparasites which could suggest potential differences between DAB genes caused by different selection pressure. Our study revealed that parasite-mediated selection is not the only variable affecting MHC diversity in European chub; however, we strongly support the role of neutral processes as the main driver of DAB diversity across populations. In addition, our study contributes to the understanding of the evolution of MHC genes in wild living fish.

• Keywords
• Genetic diversity, Major histocompatibility complex, Metazoan parasites, Microsatellites, Parasite-driven balancing selection, Phylogeography,
• MeSH
• Alleles MeSH
• Cyprinidae genetics   MeSH
• Animals, Wild MeSH
• Genetic Variation * MeSH
• Major Histocompatibility Complex genetics   MeSH
• Host-Parasite Interactions MeSH
• Microsatellite Repeats genetics   MeSH
• Fish Diseases parasitology   MeSH
• Parasitic Diseases, Animal epidemiology   genetics   parasitology   MeSH
• Parasites MeSH
• Selection, Genetic * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Europe epidemiology   MeSH

The polymorphism of exon 2 of the DAB genes (major histocompatibility complex [MHC] class IIB) was investigated for the first time in the freshwater cyprinid fish species, Squalius cephalus, in the wide range of its distribution in Europe. We identified 111 different MHC class IIB variants in 15 chub populations distributed from Finland to Spain. The sequence analysis showed that many structurally important amino acid sites that were conserved among tetrapods were also conserved in chub. The analysis of recombination indicated that it does not play an important role in producing and maintaining the variation of DAB genes analyzed in the present study. The exon 2 was shown to be subjected to intense positive selection. Phylogenetic analysis and sequence identities suggest the presence of two class IIB loci (DAB1-like and DAB3-like) in chub. Nevertheless, the presence of three DAB3-like sequence variants in several individuals indicates the duplication of the DAB3 gene. A contrasting selection pattern was found in DAB1-like and DAB3-like genes, which suggests the potential functional differences between these genes. Some DAB sequence variants were shared among the populations of different mtDNA lineages. The phylogenetic analyses did not confirm any biogeographical pattern of the genetic structure of MHC IIB in chub, which is in line with balancing selection and trans-species polymorphism in MHC genes. Nevertheless, cluster analysis based on the presence/absence of DAB sequence variants in the populations showed the phylogeophraphical pattern corresponding to the mtDNA lineages, which indicates that neutral selection can partially explain the MHC IIB evolution in chub.

• MeSH
• Cyprinidae genetics   immunology   MeSH
• Exons MeSH
• Genes, MHC Class II * MeSH
• Evolution, Molecular * MeSH
• Polymorphism, Genetic MeSH
• Selection, Genetic MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Europe MeSH