Search

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications., (© 2022 The Ecological Society of America.)

The identification of fish species using traditional methods is generally based only on morphological characteristics and these methods are currently under review. This kind of identification of hybrid fishes solely based on their morphologies may be unreliable, especially when the samples include juveniles and post-F1 lineage fishes. Therefore, in the present study, we used molecular markers to accurately identify the fish species of economic interest that are used as materials in the projects developed in research institutions. We evaluated six lots of fishes sampled from different research centers, containing a total of 84 specimens acquired from private fish farms that were considered to be the representatives of pure species. Genetic analyses of all the specimens revealed that, globally, 22 samples (26.2%) were interspecific hybrids, while 20 (90.9%) samples were surprisingly characterized as post-F1 hybrids. This result confirms that hybrids are sold in markets without adequate labeling and also indicates the lack of proper control of the commercialization and management of stocks and products in fish farms. In addition, we determined that molecular diagnosis was an extremely effective and necessary method to test the reliability of biological materials currently used in scientific research., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Deoclécio da Silva, do Prado, Hashimoto, Senhorini, Foresti and Porto-Foresti.)

Sequences of the mitochondrial gene COI (DNA Barcode) were used to identify species of rays and skates commercialized in fishmongers in Brazil. The comparisons of the obtained sequences with previously published data available in NCBI and BOLD showed that the fish products corresponded to four species, Hypanus dipterurus , Potamotrygon motoro, Paratrygon ajereba and Gymnura altavela , the last of which is classified as vulnerable according to the IUCN Red List and therefore should not be marketed in accordance with the MMA ordinance 445/2015 ., Competing Interests: The authors declare no conflicts of interest., (© 2020 The Authors.)

Sequences of the mitochondrial gene COI (DNA Barcode) wereused to identify marine fish swimming bladders commercialized in Brazil. The comparisons of the obtained sequences of the samples registered as catfish for the commerce with previously published data available in NCBI and BOLD showed that the fish products commercialized corresponded to two Perciform species, Pogonias cromis and Micropogonias furnieri. These results besides contradicting the formal identification of the species included in the fisheries control revealed an illegal trade of one of these species, M. furnieri that is threatened and consequently have its capture prohibited., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Unraveling adaptive genetic variation represents, in addition to the estimate of population demographic parameters, a cornerstone for the management of aquatic natural living resources, which, in turn, represent the raw material for breeding programs. The turbot ( Scophthalmus maximus ) is a marine flatfish of high commercial value living on the European continental shelf. While wild populations are declining, aquaculture is flourishing in southern Europe. We evaluated the genetic structure of turbot throughout its natural distribution range (672 individuals; 20 populations) by analyzing allele frequency data from 755 single nucleotide polymorphism discovered and genotyped by double-digest RAD sequencing. The species was structured into four main regions: Baltic Sea, Atlantic Ocean, Adriatic Sea, and Black Sea, with subtle differentiation apparent at the distribution margins of the Atlantic region. Genetic diversity and effective population size estimates were highest in the Atlantic populations, the area of greatest occurrence, while turbot from other regions showed lower levels, reflecting geographical isolation and reduced abundance. Divergent selection was detected within and between the Atlantic Ocean and Baltic Sea regions, and also when comparing these two regions with the Black Sea. Evidence of parallel evolution was detected between the two low salinity regions, the Baltic and Black seas. Correlation between genetic and environmental variation indicated that temperature and salinity were probably the main environmental drivers of selection. Mining around the four genomic regions consistently inferred to be under selection identified candidate genes related to osmoregulation, growth, and resistance to diseases. The new insights are useful for the management of turbot fisheries and aquaculture by providing the baseline for evaluating the consequences of turbot releases from restocking and farming.

Genetic diversity and structure of Pseudoplatystoma corruscans and P. reticulatum, large migratory South America catfishes, where overfishing and the construction of numerous dams in their feeding and reproducing areas are affecting their migratory processes negatively, were studied using microsatellites in samples from Paraguay (that comprises the Pantanal biome), and the upper and lower Paraná Basins. Genetic diversity was in accordance to that observed for other large migratory fishes, but the most geographically isolated populations of P. reticulatum and those P. corruscans subject to anthropogenic effects (stocking and dams) showed lower genetic diversity and evidences of bottlenecks compatible with low effective population size. Pseudoplatystoma reticulatum presented subtle genetic differentiation within the Paraguay area, especially between the edges of its distribution. Pseudoplatystoma corruscans, in this same area, presented a quite homogeneous but significant genetic break between the Paraguay and upper Paraná populations, apparently resulting from natural and historical isolation between the basins until recently. These data demonstrates that, although these Pseudoplatystoma spp. are abundant in the Pantanal area, anthropogenic events are leading to negative effects on their populations, particularly in the upper Paraná Basin. Genetic differentiation observed along each species distribution demands conservation actions to preserve each population's biodiversity. These results represent important genetic information using new microsatellite markers and the first genetic study of P. reticulatum covering this area of its native distribution. Data may also contribute to a better understanding of species migration patterns and to be used as a baseline for proper management., (© 2017 The Fisheries Society of the British Isles.)

The North American channel catfish Ictalurus punctatus Rafinesque 1818 is cultivated in the United States, Asia and Brazilian fish farms, and also utilized as a model species in aquaculture and genetic studies. In this work, cytogenetic analysis of . punctatus from Brazilian aquaculture revealed for the first time the presence of extra elements (supernumerary or B chromosomes) in this species. These elements were characterized as dot-like micro B chromosomes and were found in three individuals (varying from 0 to 1) and in one individual with higher incidence per cell (varying from 0 to 5; mean number of Bs per cell = 2.01). More specific cytogenetic techniques in this individual revealed 58 A chromosomes (standard complement) containing heterochromatic bands in the centromeric regions, a single Ag-NOR in a subtelocentric pair (also positive for 18S rDNA using the FISH technique) and multiple 5S rDNA clusters in three different subtelocentric chromosomes. Four B chromosomes were entirely Ag-NOR positive (also fully heterochromatic) and three presented 18S rDNA clusters by FISH. The occurrence of Ag-NOR and 18S ribosomal genes in both A and B chromosome complements may indicate an intraspecific origin for these extra chromosomes. Additionally, the terminal location of 18S ribosomal clusters in the Ag-NOR-bearing chromosomes and the presence of active NOR in the B chromosomes suggested that breakage events may be related to a possible recent origin of these extra elements. We suggest this data may be useful as cytogenetic information for future elucidation of the composition, origin and evolution of extra chromosomes in fishes.

The cytogenetic characteristics of Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum and their F1, F2 and backcross hybrids were assessed by using chromosome banding techniques. The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes. Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens. Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals. For parental and hybrid lineages, 18S ribosomal clusters corresponding to NORs and 5S ribosomal genes were identified in distinct pairs of chromosomes. The striking conservation in the chromosomal macrostructure of the parental species may account for the fertility of their F1 hybrids. Similarly, the lack of marked alterations in the chromosomal structure of the F1 hybrids could account for the maintenance of these features in post-F1 lineages.