Genetic identification of interspecific hybrid of Neotropical catfish species (Pseudoplatystoma corruscans vs. Pseudoplatystoma reticulatum) in rivers of Mato Grosso do Sul State, Brazil

Abstract

Hybrids of the species Pseudoplatystoma corruscans vs. Pseudoplatystoma reticulatum are extensively traded because they are more docile and precocious compared to their parents. This study aimed to identify the occurrence of hybrid 'Surubim' in rivers of the State of Mato Grosso do Sul, applying molecular techniques. Pseudoplatystoma corruscans, Pseudoplatystoma reticulatum and hybrid 'Surubim' were detected using multiplex PCR and PCR-RFLP in RAG2, GLOBIN, EF1α, 18S rRNA nuclear genes, and mitochondrial 16S rRNA gene. The results revealed the presence of F 1 hybrids in rivers and the occurrence of genetic introgression, evidenced by the Post-F 1 hybrids. Furthermore, discrepancies between the morphological and genetic identification were observed, demonstrating the effectiveness of using different molecular markers for the correct identification of these hybrids. The necessity of implementation of management and conservation projects to maintain the genetic integrity of native species populations threatened by hybridization in the rivers of Mato Grosso do Sul State is evident.Híbridos envolvendo as espécies Pseudoplatystoma corruscans vs. Pseudoplatystoma reticulatum são amplamente comercializados por apresentarem maior docilidade e precocidade quando comparados aos parentais. Neste trabalho objetivou-se identificar, por meio de técnicas moleculares, a existência de surubins híbridos em rios do estado do Mato Grosso do Sul. Pseudoplatystoma corruscans, Pseudoplatystoma reticulatum e 'Surubim' híbrido foram identificados utilizando as técnicas de PCR multiplex e PCR-RFLP dos genes nucleares RAG2, GLOBINA, EF1α, 18S rRNA e mitocondrial 16S rRNA. Os resultados demonstraram a presença de híbridos F 1 em rios e a ocorrência da introgressão genética, evidenciada pelos híbridos Pós-F 1 . Além disso, foram observadas discrepâncias entre a identificação morfológica e genética, demonstrando a eficácia da utilização de diversos marcadores moleculares para identificação correta destes híbridos. Torna-se evidente a necessidade da implantação de projetos de manejo e conservação, a fim de manter a integridade genética de populações de espécies nativas em rios do estado do Mato Grosso do Sul, que encontram-se ameaçadas pela hibridação.

Genetic variability of pure Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum individuals in the Paraná and Paraguay River basins

“…This can bring more reliability to the results because morphological identification alone may not be enough to discriminate a pure individual from a hybrid one, as demonstrated by Vaini et al [19]. Molecular tools for the genetic identification of hybrid and pure surubins were, therefore, used in the current study, prior to the study with microsatellite molecular markers, to evaluate the genetic variability of these populations.…”

“…The DNA extraction process, multiplex-PCR, and PCR-RFLP using RAG2, GLOBINA, EF1α, and 18S nuclear genes, as well as the 16S rRNA mitochondrial gene, were performed in Vaini et al [19]. For this study, only Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum identified as genetically pure were used to evaluate the genetic diversity with microsatellite molecular markers.…”

“…Microsatellite markers in fish have been used to study heterozygosity, the structure of populations with a focus on conservation and management, migration patterns, the effects of environmental fragmentation, reproductive systems, and phylogenetic relationships, among others factors [15,16]. Before characterizing the genetic variability of pure populations; however, it important identify if the fishes are pure species or hybrids [17][18][19]. There have been studies of the genetic variability of P. corruscans and P. reticulatum using microsatellite molecular markers [12,20,21], but none have genetically identified the individuals in order to determine whether they were genetically pure before performing the study of genetic variability.…”

Molecular identification of intergenus crosses involving catfish hybrids: risks for aquaculture production

“…In long term, backcross can cause genetic introgression and contamination of wild pure stocks, and may even lead to local extinction of populations, as observed in several other species (Allendorf et al, 2001;Epifanio & Philipp, 2001). In fact, the occurrence of hybrid cachapinta has already been detected in natural environments in Brazil (Prado et al, 2012b;Vaini et al, 2014), threatening natural populations, possibly due to escapes of aquaculture systems. Therefore, the trade and management of hybrids cachapinta need receive special attention in the aquaculture industry, especially because hybrids are sold commercially as one of the parental species (present study).…”

“…Furthermore, hybrids can be used as broodstock resulting in high mortality rates or lost of the hybrid vigor in the offspring (Mia et al, 2005;Hashimoto et al, 2013). In the environment, if released or escape to the rivers, hybrids can backcross with the native pure species, causing genetic introgression and contaminating the genetic pool of pure stocks (Prado et al, 2012a(Prado et al, , 2012bVaini et al, 2014).…”