Genetic divergence between Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Siluriformes: Pimelodidae) in the Paraná River Basin

Abstract

Pseudoplatystoma corruscans (Spix and Agassiz, 1829) and Pseudoplatystoma reticulatum (Eingenmann and Eigenmann, 1889) are large migratory catfishes of high biological importance and great commercial value in South America. Because fertile crossbreeds can be artificially produced in hatcheries, a high genetic proximity between these two Pimelodidae species is conceivable. Possible escape of crossbred specimens from pisciculture stations is a serious environmental concern. Despite their importance, knowledge of P. corruscans and P. reticulatum biology, ecology, population diversity and genetics is limited. In the present work, the genetic divergence between P. corruscans and P. reticulatum populations from the Paraná River Basin was analyzed on the basis of polymorphisms in ISSR fragments and in the hypervariable sequence of the mitochondrial DNA (mtDNA) control region. Estimates of intraspecific haplotype (h > 0.5) and nucleotide diversities (π < 0.01) indicate that P. corruscans and P. reticulatum have survived a historical population decline, followed by a demographic expansion. The interspecific polymorphisms within the mtDNA control region and ISSR fragments were suitable as diagnostic molecular markers and could be used to discriminate the two species. A unique Pseudoplatystoma specimen, captured in the Upper Paraná River Floodplain, was identified by these DNA diagnostic markers as a hybrid P. reticulatum × P. corruscans, which possibly escaped from pisciculture. The integrity of the natural population of P. corruscans in the Upper Paraná River is at risk of genetic introgression or homogenization due to the presence of hybrids and the transposition of P. reticulatum upstream through the Canal da Piracema at Itaipu Dam. Data presented herein improve the understanding of the genetic relatedness between P. corruscans and P. reticulatum and represent potential tools for future programs of conservation and surveillance of genetic introgression events and the genetic integrity of these populations. isolated fish populations, and this is especially threatening to the dispersion of species that undergo long-distance reproduction migrations, such as P. corruscans. Therefore, monitoring of populations is becoming essential for preserving both Pseudoplatystoma species. Molecular markers are fundamental for monitoring population genetic variability and for the surveillance of populations that are potentially at risk of losing their genetic integrity. In addition, they represent an important tool for studies of the genetic diversity and evolution of fishes. The availability of nuclear and mitochondrial DNA markers that are easily accessible and suitable for characterizing and discriminating P. corruscans and P. reticulatum is a fundamental requirement in the study and supervision of these populations. Moreover, these molecular markers could enable a better understanding of the genetic relatedness of these two species.ISSR (Inter Simple Sequence Repeats) fingerprinting is a feasible molecular tool that does ...

A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin

“…Large migratory fishes like Salminus brasiliensis (dourado), Pseudoplatystoma corruscans (pintado), Brycon orbignyanus (piracanjuva), Pinirampus pirinampu (barbado), Hemisorubim platyrhynchos (jurupoca), Prochilodus lineatus (corimba), Piaractus mesopotamicus (pacú) and Zungaro jahu (jaú) are common in both ecoregions. Population genetics studies of some of these species above and below the Itaipu Dam suggest they are not isolated populations (Bignoto et al, 2009). These findings suggest that in years of very high discharge, individuals of large migratory species were able to cross the barrier of the Sete Quedas Falls in both directions.…”

Genetic diversity of Arapaima gigas (Schinz, 1822) (Osteoglossiformes: Arapaimidae) in the Araguaia-Tocantins basin estimated by ISSR marker

“…Due to its ease of use, low cost and high sensitivity, ISSR markers have been employed in studies on genetic diversity of several species of plants and animals (Luque et al, 2002;Bornet & Branchard, 2004;Askari et al, 2011;Moresco et al, 2013), as well as studies of sexual differentiation in plants (Ehsanpour et al, 2008) and identification of hybrid fish (Bignotto et al, 2009;AlmeidaFerreira et al, 2011). This marker has allowed the analysis of the main parameters used for determining the genetic diversity and the level of differentiation between species and natural populations of Neotropical fish (amount of polymorphic loci, expected or average heterozygosity and the number of migrants per generation) (Paiva et al, 2006;Sofia et al, 2006;Lopes et al, 2008;Antunes et al, 2010;Almeida-Ferreira et al, 2011;Domingos et al, 2014).…”

Impacts of stocking on the genetic diversity of Colossoma macropomum in central Amazon, Brazil

“…For species with high economic value in aquaculture, ISSR has been used alone or in conjunction with mtDNA, to access intra-and interspecific phylogenetic relationships, and variation between stocks or their genetic structure (Bignotto et al, 2009;Xiaoxiao et al, 2011). In the present study, the 10 ISSR primers selected showed optimal efficiency, producing polymorphic patterns above 88.2% for the three broodstocks studied.…”