Obligate brood parasites delegate the workload of costly parental care to their hosts. Theory predicts that release from demanding parental care increases the importance of other factors to shape mating patterns. However, behavioural observations and parentage estimates are notoriously difficult to obtain in species with covert reproductive strategies, such as brood parasites, and evidence for their mating strategies are scarce. Molecular genetic methods provide a powerful tool to identify concealed mating patterns. Here, we reconstruct the parentage of cuckoo catfish (Synodontis multipunctatus) clutches collected in the wild using a combination of newly developed microsatellite markers, mitochondrial markers, and maximum likelihood estimates of pairwise relatedness. Cuckoo catfish parasitise mouthbrooding cichlids in Lake Tanganyika, but a natural spawning of the brood parasite has never been observed. We examined 429 females of confirmed host cichlid species (parasitism prevalence 6%; 24 parasitised clutches with 1-14 embryos) and found that 46% of clutches with three or more offspring (i.e., 6 out of 13) were parented by more than two catfish individuals. We demonstrated variable mating patterns including polyandrous and polygynous mating, and host sharing by separate, genetically monogamous, catfish pairs. This indicates that cuckoo catfish parasitism involves groups of catfish with reduced capability to monopolise mating opportunities. In general, our results demonstrate how reproductive strategy and mating patterns in a species with concealed breeding behaviour can be investigated and provide valuable insights into the mating system of a brood parasitic species other than hitherto studied avian brood parasites.

• Klíčová slova
• Synodontis multipunctatus, African cichlids, Lake Tanganyika, parentage analysis, reproductive parasitism, reproductive success,
• MeSH
• cichlidy * genetika   fyziologie   MeSH
• jezera MeSH
• mikrosatelitní repetice * genetika   MeSH
• mitochondriální DNA genetika   MeSH
• rozmnožování * genetika   MeSH
• sexuální chování zvířat * MeSH
• sumci * genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Tanzanie MeSH
• Názvy látek
• mitochondriální DNA MeSH

Hybrid sterility, a hallmark of postzygotic isolation, arises from parental genome divergence disrupting meiosis. While chromosomal incompatibility is often implicated, the underlying mechanisms remain unclear. This study investigated meiotic behavior and genome-wide divergence in bighead catfish (C. macrocephalus), North African catfish (C. gariepinus), and their sterile male hybrids (important in aquaculture). Repetitive DNA analysis using bioinformatics and cytogenetics revealed significant divergence in satellite DNA (satDNA) families between parental species. Notably, one hybrid exhibited successful meiosis and spermatozoa production, suggesting potential variation in sterility expression. Our findings suggest that genome-wide satDNA divergence, rather than chromosome number differences, likely contributes to meiotic failure and male sterility in these catfish hybrids.

• Klíčová slova
• Chromosome pairing, Clariid catfish, Hybrid sterility, Immunostaining, Synaptonemal complex,
• MeSH
• genom MeSH
• hybridizace genetická * MeSH
• meióza * MeSH
• mužská infertilita * genetika   veterinární   MeSH
• nemoci ryb * genetika   MeSH
• satelitní DNA * genetika   MeSH
• sumci * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• severní Afrika MeSH
• Názvy látek
• satelitní DNA * MeSH

Albinism is a widespread departure from a typical body colouration due to altered melanin production. The Wels catfish (Silurus glanis) is among the largest freshwater fish species in the world, and albino individuals occur both in the wild and in aquaculture. Here, we performed transcriptome-wide analysis of albino and normally pigmented S. glanis using four tissues (skin, dorsal fin, whole eye and liver) to identify genes associated with albinism by exploring patterns of differential expression (DE) and differential alternative splicing (DAS). Multi-tissue analyses revealed a large number of genes in skin (n = 1355) and fin (n = 614) tissue associated with the albino phenotype in S. glanis, while the number of DE genes in eye and liver tissues was lower (n = 188, n = 189, respectively). Several DE genes across multiple tissues were detected as the most promising candidates (e.g., hsp4, hsp90b1, raph1, uqcrfs1, adcy-family and wnt-family) potentially causally linked to the albino phenotype in Wels catfish. Moreover, our findings supported earlier observations of physiological differences between albino and normally pigmented individuals, particularly in energy metabolism and immune response. In contrast, there were only a few pigmentation-related genes observed among DAS genes (4 in skin, 2 in fin), the overlap between DAS and DE genes was low (n = 25) and did not include known pigmentation-related genes. This suggests that DAS and DE in Wels catfish are, to a large extent, independent processes, and the observed alternative splicing cases are probably not causally linked with albinism in S. glanis. This work provides the first transcriptome-wide multi-tissue insights into the albinism of Wels catfish and serves as a valuable resource for further understanding the genetic mechanisms of pigmentation in fish.

• Klíčová slova
• ADCY, Catfish, Fish, Genomics, HPS4, Omics, Pigmentation-related genes, Transcriptome, WNT,
• MeSH
• albinismus * genetika   MeSH
• alternativní sestřih MeSH
• stanovení celkové genové exprese MeSH
• sumci * genetika   metabolismus   MeSH
• transkriptom MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Host-parasite dynamics involve coevolutionary arms races, which may lead to host specialization and ensuing diversification. Our general understanding of the evolution of host specialization in brood parasites is compromised by a restricted focus on bird and insect lineages. The cuckoo catfish (Synodontis multipunctatus) is an obligate parasite of parental care of mouthbrooding cichlids in Lake Tanganyika. Given the ecological and taxonomic diversity of mouthbrooding cichlids in the lake, we hypothesized the existence of sympatric host-specific lineages in the cuckoo catfish. In a sample of 779 broods from 20 cichlid species, we found four species parasitized by cuckoo catfish (with prevalence of parasitism of 2%-18%). All parasitized cichlids were from the tribe Tropheini, maternal mouthbrooders that spawn over a substrate (rather than in open water). Phylogenetic analysis based on genomic (ddRAD sequencing) and mitochondrial (Dloop) data from cuckoo catfish embryos showed an absence of host-specific lineages. This was corroborated by analyses of genetic structure and co-ancestry matrix. Within host species, parasitism was not associated with any individual characteristic we recorded (parent size, water depth), but was costly as parasitized parents carried smaller clutches of their own offspring. We conclude that the cuckoo catfish is an intermediate generalist and discuss costs, benefits and constraints of host specialization in this species and brood parasites in general.

• Klíčová slova
• brood parasitism, fish, host specialisation, host-parasite relationship, interspecific interactions, social evolution,
• MeSH
• cichlidy * genetika   MeSH
• fylogeneze MeSH
• hnízdění MeSH
• interakce hostitele a parazita genetika   MeSH
• paraziti * MeSH
• sumci * genetika   MeSH
• voda MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• voda MeSH

The Neotropical monophyletic catfish genus Harttia represents an excellent model to study karyotype and sex chromosome evolution in teleosts. Its species split into three phylogenetic clades distributed along the Brazilian territory and they differ widely in karyotype traits, including the presence of standard or multiple sex chromosome systems in some members. Here, we investigate the chromosomal rearrangements and associated synteny blocks involved in the origin of a multiple X1X2Y sex chromosome system present in three out of six sampled Amazonian-clade species. Using 5S and 18S ribosomal DNA fluorescence in situ hybridization and whole chromosome painting with probes corresponding to X1 and X2 chromosomes of X1X2Y system from H. punctata, we confirm previous assumptions that X1X2Y sex chromosome systems of H. punctata, H. duriventris and H. villasboas represent the same linkage groups which also form the putative XY sex chromosomes of H. rondoni. The shared homeology between X1X2Y sex chromosomes suggests they might have originated once in the common ancestor of these closely related species. A joint arrangement of mapped H. punctata X1 and X2 sex chromosomes in early diverging species of different Harttia clades suggests that the X1X2Y sex chromosome system may have formed through an X chromosome fission rather than previously proposed Y-autosome fusion.

• MeSH
• chromozom Y MeSH
• fylogeneze MeSH
• hybridizace in situ fluorescenční MeSH
• pohlavní chromozomy genetika   MeSH
• sumci * genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Rineloricaria is the most diverse genus within the freshwater fish subfamily Loricariinae, and it is widely distributed in the Neotropical region. Despite limited cytogenetic data, records from southern and south-eastern Brazil suggest a high rate of chromosomal rearrangements in this genus, mirrored in remarkable inter- and intraspecific karyotype variability. In the present work, we investigated the karyotype features of Rineloricaria teffeana, an endemic representative from northern Brazil, using both conventional and molecular cytogenetic techniques. We revealed different diploid chromosome numbers (2n) between sexes (33♂/34♀), which suggests the presence of an ♀X1 X1 X2 X2 /♂X1 X2 Y multiple sex chromosome system. The male-limited Y chromosome was the largest and the only biarmed element in the karyotype, implying Y-autosome fusion as the most probable mechanism behind its origination. C-banding revealed low amounts of constitutive heterochromatin, mostly confined to the (peri)centromeric regions of most chromosomes (including the X2 and the Y) but also occupying the distal regions of a few chromosomal pairs. The chromosomal localization of the 18S ribosomal DNA (rDNA) clusters revealed a single site on chromosome pair 4, which was adjacent to the 5S rDNA cluster. Additional 5S rDNA loci were present on the autosome pair 8, X1 chromosome, and in the presumed fusion point on the Y chromosome. The probe for telomeric repeat motif (TTAGGG)n revealed signals of variable intensities at the ends of all chromosomes except for the Y chromosome, where no detectable signals were evidenced. Male-to-female comparative genomic hybridization revealed no sex-specific or sex-biased repetitive DNA accumulations, suggesting a presumably low level of neo-Y chromosome differentiation. We provide evidence that rDNA sites might have played a role in the formation of this putative multiple sex chromosome system and that chromosome fusions originate through different mechanisms among different Rineloricaria species.

• Klíčová slova
• Amazon basin, Robertsonian fusion, fluorescence in situ hybridization, repetitive DNA, sex chromosome evolution,
• MeSH
• chromozom Y MeSH
• karyotyp MeSH
• pohlavní chromozomy MeSH
• ribozomální DNA MeSH
• srovnávací genomová hybridizace MeSH
• sumci * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ribozomální DNA MeSH

The wels catfish (Silurus glanis) is one of the largest freshwater fish species in the world. This top predator plays a key role in ecosystem stability, and represents an iconic trophy-fish for recreational fishermen. S. glanis is also a highly valued species for its high-quality boneless flesh, and has been cultivated for over 100 years in Eastern and Central Europe. The interest in rearing S. glanis continues to grow; the aquaculture production of this species has almost doubled during the last decade. However, despite its high ecological, cultural and economic importance, the available genomic resources for S. glanis are very limited. To fulfill this gap we report a de novo assembly and annotation of the whole genome sequence of a female S. glanis The linked-read based technology with 10X Genomics Chromium chemistry and Supernova assembler produced a highly continuous draft genome of S. glanis: ∼0.8Gb assembly (scaffold N50 = 3.2 Mb; longest individual scaffold = 13.9 Mb; BUSCO completeness = 84.2%), which included 313.3 Mb of putative repeated sequences. In total, 21,316 protein-coding genes were predicted, of which 96% were annotated functionally from either sequence homology or protein signature searches. The highly continuous genome assembly will be an invaluable resource for aquaculture genomics, genetics, conservation, and breeding research of S. glanis.

• Klíčová slova
• 10X Genomics Chromium linked-reads, Silurus glanis, de novo assembly, teleost, wels catfish, whole genome sequencing,
• MeSH
• ekosystém * MeSH
• genom MeSH
• sladká voda MeSH
• sumci * genetika   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH

Cryptic genetic diversity and erroneous morphological species determination represent frequent problems in biodiversity research. Here, examination of 138 specimens of Synodontis (Mochokidae, Siluriformes) from the Nile River and Lake Turkana revealed the presence of both S. schall-like and S. frontosus-like morphotypes, with a phenotypic gradient between them. We concluded phylogenetic and population genetic analyses based on two mitochondrial and one nuclear marker including 131 coxI (565 bp), 96 cytb (973 bp) and 19 RAG2 (896 bp) sequences from the Nile-Turkana population, plus additional GenBank data of Synodontis spp. Whilst nuclear data were inconclusive, mitochondrial sequences suggested that both morphotypes and intermediate forms are conspecific. The results imply probable synonymy of S. frontosus with S. schall. Conversely, a strong biogeographical signal was revealed among widely distributed and supposedly conspecific S. schall-like catfish of the Nilo-Sudanian ichthyological province. Synodontis schall sensu stricto (=Eastern clade), as defined by type locality in the Nile, is apparently restricted to the eastern part of the Nilo-Sudanian ichthyological province (e.g. Nile, Turkana, Chad). Synodontis schall Western clade (Senegambia, Niger, Chad) most probably represents a cryptic taxon, unrecognized thus far due to the absence of distinctive morphological differences.

• MeSH
• Bayesova věta MeSH
• biodiverzita * MeSH
• cytochromy b klasifikace   genetika   MeSH
• fylogeneze MeSH
• haplotypy MeSH
• populační genetika MeSH
• respirační komplex IV klasifikace   genetika   MeSH
• sumci klasifikace   genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytochromy b MeSH
• respirační komplex IV MeSH

The catfish family Siluridae contains 107 described species distributed in Asia, but with some distributed in Europe. In this study, karyotypes and other chromosomal characteristics of 15 species from eight genera were examined using conventional and molecular cytogenetic protocols. Our results showed the diploid number (2n) to be highly divergent among species, ranging from 2n = 40 to 92, with the modal frequency comprising 56 to 64 chromosomes. Accordingly, the ratio of uni- and bi-armed chromosomes is also highly variable, thus suggesting extensive chromosomal rearrangements. Only one chromosome pair bearing major rDNA sites occurs in most species, except for Wallago micropogon, Ompok siluroides, and Kryptoterus giminus with two; and Silurichthys phaiosoma with five such pairs. In contrast, chromosomes bearing 5S rDNA sites range from one to as high as nine pairs among the species. Comparative genomic hybridization (CGH) experiments evidenced large genomic divergence, even between congeneric species. As a whole, we conclude that karyotype features and chromosomal diversity of the silurid catfishes are unusually extensive, but parallel some other catfish lineages and primary freshwater fish groups, thus making silurids an important model for investigating the evolutionary dynamics of fish chromosomes.

• Klíčová slova
• CGH, FISH, chromosome banding, fish cytotaxonomy, rDNA classes,
• MeSH
• cytogenetické vyšetření MeSH
• genetická variace * MeSH
• genom * MeSH
• genomika * metody   MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp * MeSH
• pruhování chromozomů MeSH
• repetitivní sekvence nukleových kyselin * MeSH
• srovnávací genomová hybridizace MeSH
• sumci klasifikace   genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Biogeographical and ecological barriers strongly affect the course of micro-evolutionary processes in free living organisms. Here we assess the impact of a recently emerged barrier on populations of limnic fauna. Genetic diversity and population structure in a host-parasite system (Wenyonia virilis tapeworm, Synodontis schall catfish) are analyzed in the recently divided Turkana and Nile basins. The two basins, were repeatedly connected during the Holocene wet/dry climatic oscillations, following late Pleistocene dessication of the Turkana basin. Mitochondrial DNA sequences for cytochrome oxidase I gene (cox I) and a whole genome scanning method-amplified fragment length polymorphism (AFLP) were employed. A total of 347 cox I sequences (representing 209 haplotypes) and 716 AFLP fragments, as well as 120 cox I sequences (20 haplotypes) and 532 AFLP fragments were obtained from parasites and hosts, respectively. Although results indicate that host and parasite populations share some formative traits (bottlenecks, Nilotic origin), their population histories/patterns differ markedly. Mitochondrial analysis revealed that parasite populations evolve significantly faster and show remarkably higher genetic variability. Analyses of both markers confirmed that the parasites undergo lineage fission, forming new clusters specific for either freshwater or saline parts of Lake Turkana. In congruence with the geological history, these clusters apparently indicate multiple colonisations of Lake Turkana from the Nile. In contrast, the host population pattern indicates fusion of different colonisation waves. Although fish host populations remain connected, saline habitats in Lake Turkana (absent in the Nile), apparently pose a barrier to the gene flow in the parasite, possibly due to its multihost lifecycle, which involves freshwater annelids. Despite partially corroborating mitochondrial results, AFLP data was not sufficiently informative for analyzing populations with recently mixed biogeographic histories.

• MeSH
• Cestoda genetika   MeSH
• cestodózy genetika   parazitologie   veterinární   MeSH
• ekosystém MeSH
• extrémní prostředí * MeSH
• fylogeneze MeSH
• haplotypy MeSH
• interakce hostitele a parazita genetika   MeSH
• jezera MeSH
• mitochondriální DNA MeSH
• molekulární evoluce * MeSH
• nemoci ryb genetika   parazitologie   MeSH
• polymorfismus genetický MeSH
• proteiny červů genetika   MeSH
• respirační komplex IV genetika   MeSH
• slané vody MeSH
• sumci genetika   parazitologie   MeSH
• teoretické modely MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Keňa MeSH
• Názvy látek
• mitochondriální DNA MeSH
• proteiny červů MeSH
• respirační komplex IV MeSH