Cytogenetic markers as diagnoses in the identification of the hybrid between Piauçu (Leporinus macrocephalus) and Piapara (Leporinus elongatus)

Abstract

The genetic monitoring of interspecific hybrids involves the application of methodologies able to provide an easy and indubitable genetic characterization of both parental and hybrid individuals. In the present work, cytogenetic techniques were used to identify a hybrid lineage of "Piaupara" in order to caracterize them in relation to the parental species, Leporinus macrocephalus (piauçu) and L. elongatus (piapara). The cytogenetic analysis revealed that L. macrocephalus presented 2n = 54 chromosomes and a nucleolar organizer regions (NOR) at the telomere of the long arm of the submetacentric chromosome pair 2. Analysis of constitutive heterochromatin (C-banding) revealed a conspicuous block at the pericentromeric region on the long arm of a submetacentric chromosome pair. L. elongatus presented the same diploid number, 2n = 54, and a karyotypic formula similar to that of L. macrocephalus. The NORs were also at the telomere of the long arm of the submetacentric pair 2, which was morphologically different from that of L. macrocephalus. Heterochromatic blocks were observed at both telomeres of a submetacentric chromosome pair. The hybrid "Piaupara" presented the same diploid number (2n = 54) and karyotypic formula as the parental species and there were no visible differences between parental and hybrid individuals. Differently from the Giemsa staining, NOR-and C-banding analysis showed marked differences which allowed the identification of the hybrids by the different morphology and/or size of the chromosomes carrying the NORs and patterns of heterochromatin distribution in their chromosomes. Such genetic studies are important for fish culture since they can provide tools for monitoring natural and artificial hybridization. They are also useful in biological conservation programmes and in the proper management of natural and reared fish stocks.

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

“…Nevertheless, due to the lack of methods for the identification of species and for the supervision and proper management of fish products, hybrids can be confused with their parents and introduced into natural environments through escapes from fish farm tanks or breeding stations and "pesque-e-pague" sites (Porto-Foresti et al, 2008;Hashimoto et al, 2012a).…”

“…The escape of the interspecific hybrid 'Surubim' to the natural environment, along with the lack of mechanisms for its identification, can reduce the genetic integrity of pure parental species, because the hybrid is fertile and can backcross with its pure parentals, causing genetic introgression (Marques, 2002;Porto-Foresti et al, 2008;Hashimoto et al, 2012b).…”

Crescimento de juvenis de Pseudoplatystoma reticulatum e Pseudoplatystoma spp. em viveiro

“…O cruzamento de peixes de água doce é utilizado com o intuito de promover o melhoramento genético e por esta razão muitos produtores realizam a hibridação interespecífica entre o cachara P. reticulatum e o pintado P. corruscans (PORTO-FORESTI et al, 2008). A justificativa para se produzir híbridos na piscicultura são as seguintes: diminuir o tempo de engorda, para que os peixes atinjam maior ganho de peso em menor tempo de criação, obter indivíduos mais dóceis e facilitar o manejo, principalmente para o rápido aprendizado durante o treinamento alimentar (FERNANDES, 2010).…”

Hybrids between Pseudoplatystoma corruscans and P. reticulatum (Siluriformes: Pimelodidae) previously reported in the Upper Paraná River are likely escapes from aquaculture farms: evidence from microsatellite markers

“…Most hybrids sampled by vAini et al (2014) in the Upper Paraná River basin and Paraguay basin correspond to "cachapinta", which is also the most traded hybrid in fish farms (PoRto-foReSti et al 2011, PRAdo et al 2012a, vAini et al 2014. Furthermore, hybrids have already been collected in low frequency (3.6%) in an upper stretch of the Upper Paraná River, close to Ilha Solteira Dam, between 2003and 2008(PRAdo et al 2012a. During the period of these studies, A.B.…”

“…In order to meet market demands in the face of decreasing populations, farming of the 'pintado' and its hybrid with the 'cachara', Pseudoplatystoma reticulatum (Eigenmann & Eigenmann, 1889), has increased in the region, (cARvAlho et al 2013). With that, concerns about the possibility of escapes from aquaculture farms have also increased, since farmed hybrids 'pintachara' (crossbreed between female 'pintado' and male 'cachara') and 'cachapinta' (crossbreed between female 'cachara' and male 'pintado') can potentially hybridize with natural populations of P. corruscans (feRnAndeS et al 2003, PoRto-foReSti et al 2008, PRAdo et al 2012a, hAShimoto et al 2012 5790,PR, ABSTRACT. The production of hybrids of the 'pintado', Pseudoplatystoma corruscans (Spix & Agassiz, 1829) and 'cachara', Pseudoplatystoma reticulatum (Eigenmann & Eigenmann, 1889) in captivity has generated many concerns about the possibility of introduction of farmed hybrids into natural environments.…”