Hybridization is strongly constrained by salinity during secondary contact between silverside fishes (Odontesthes, Atheriniformes).

This study investigates a contact zone between two silverside fish species (marine Odontesthes argentinensis and freshwater O. bonariensis) in the estuarine Mar Chiquita lagoon along the Atlantic coast in Argentina (MChL), in which intermediate morphs had been reported. It has been suggested that admixture and introgression occur in MChL between these two species, but direct genetic evidence is lacking.

Molecular and morphological evidence revalidates (Characiformes, Characidae) and shows hidden diversity.

We conducted a revision of the Neotropical genus . A previous study synonymized the species, , distributed from the western portion of the Amazon River to the north-western region of the La Plata River Basin, and , with type locality in the Lipeo River in Bolivia. We revisited this result by collecting new morphometric, meristic, and genetic data ( mitochondrial gene) for 24 individuals distributed along La Plata River Basin in Argentina, and discussed our results in the context of multiple biogeographic processes of isolation in that basin.

Processes that drive the population structuring of (Cyprinidontiformes, Anablepidae) in the La Plata Basin.

The distribution of genetic diversity across a species distribution range is rarely homogeneous, as the genetic structure among populations is related to the degree of isolation among them, such as isolation by distance, isolation by barrier, and isolation by environment. is a small viviparous fish that inhabits a wide range of habitats in South America. To decipher the isolation processes that drive population structuring in we analyzed 221 sequences of the mitochondrial (COI), from 19 localities.

Multilocus phylogeny and historical biogeography of Hypostomus shed light on the processes of fish diversification in La Plata Basin.

Distribution history of the widespread Neotropical genus Hypostomus was studied to shed light on the processes that shaped species diversity. We inferred a calibrated phylogeny, ancestral habitat preference, ancestral areas distribution, and the history of dispersal and vicariance events of this genus. The phylogenetic and distribution analyses indicate that Hypostomus species inhabiting La Plata Basin do not form a monophyletic clade, suggesting that several unrelated ancestral species colonized this basin in the Miocene.

Biogeography, habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data.

Rivers and lake systems in the southern cone of South America have been widely influenced by historical glaciations, carrying important implications for the evolution of aquatic organisms, including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New double digest restriction-site associated DNA data presented here provide a robust framework to investigate the biogeographical history of and habitat transitions in Odontesthes.

An integrated approach clarifies the cryptic diversity in Hypostomus Lacépède 1803 from the Lower La Plata Basin.

Hypostomus commersoni Valenciennes 1836, Hypostomus cordovae (Günther 1880) and Hypostomus laplatae (Eigenmann 1907) have been little studied since their original descriptions. This study shows a comprehensive review of these species from the Lower La Plata Basin, including their taxonomic history, distribution, color patterns, morphology, and ecological and molecular phylogenetic data. Morphological and phylogenetic analyses based on D-loop sequences suggested that H.

A continental-wide molecular approach unraveling mtDNA diversity and geographic distribution of the Neotropical genus Hoplias.

With an estimate of around 9,000 species, the Neotropical region hosts the greatest diversity of freshwater fishes of the world. Genetic surveys have the potential to unravel isolated and unique lineages and may result in the identification of undescribed species, accelerating the cataloguing of extant biodiversity. In this paper, molecular diversity within the valuable and widespread Neotropical genus Hoplias was assessed by means of DNA Barcoding.

Unexpected diversity in the catfish Pseudancistrus brevispinis reveals dispersal routes in a Neotropical center of endemism: the Guyanas Region.

Neotropical freshwater fishes have reached an unrivalled diversity, organized into several areas of endemism, yet the underlying processes are still largely unknown. The topographical and ecological characteristics of the Guyanas Region make it an ideal area of endemism in which to investigate the forces that have shaped this great diversity. This region is thought to be inhabited by species descending from Amazonian ancestors, which would have used two documented routes that, however, hardly explain the entrance of species adapted to running waters.