Molecular characterization and genetic relationships of seven piranha species of the genera Serrasalmus and Pygocentrus (Characiformes: Serrasalmidae) from Paraná-Paraguay, São Francisco and Tocantins River basins in Brazil / Caracterização molecular e relações genéticas de sete espécies de piranhas dos gêneros Serrasalmus e Pygocentrus (Characiformes: Serrasalmidae) das bacias hidrográficas Paraná-Paraguai, São Francisco e Tocantins, no Brasil

Abstract Genetic and phylogenetic relationships among seven piranha species of the genera Serrasalmus and Pygocentrus from the Paraná-Paraguay, São Francisco and Tocantins River basins were evaluated in the present study by partial sequences of two mitochondrial genes, Cytochrome b and Cytochrome c Oxidase I. Phylogenetic analysis of Maximum-Likelihood and Bayesian inference were performed. Results indicated, in general, greater genetic similarity between the two species of Pygocentrus (P. nattereri and P. piraya), between Serrasalmus rhombeus and S. marginatus and between S. maculatus, S. brandtii and S. eigenmanni. Pygocentrus nattereri, S. rhombeus and S. maculatus showed high intraspecific genetic variability. These species have each one, at least two different mitochondrial lineages that, currently, occur in sympatry (S. rhombeus) or in allopatry (P. nattereri and S. maculatus). Species delimitation analysis and the high values of genetic distances observed between populations of S. rhombeus and of S. maculatus indicated that each species may corresponds to a complex of cryptic species. The non-monophyletic condition of S. rhombeus and S. maculatus reinforces the hypothesis. The geographic distribution and the genetic differentiation pattern observed for the piranha species analyzed herein are discussed regarding the geological and hydrological events that occurred in the hydrographic basins.

Resumo Relações genéticas e filogenéticas de sete espécies de piranhas dos gêneros Serrasalmus e Pygocentrus das bacias hidrográficas Paraná-Paraguai, São Francisco e Tocantins foram avaliadas com base em sequências parciais dos genes mitocondriais Citocromo b e Citocromo c Oxidase I. Foram realizadas análises filogenéticas de Máxima Verossimilhança e de inferência Bayesiana. Os resultados indicaram, em geral, maior similaridade genética entre as duas espécies de Pygocentrus (P. nattereri e P. piraya), entre Serrasalmus rhombeus e S. marginatus e entre S. maculatus, S. brandtii e S. eigenmanni. Pygocentrus nattereri, S. rhombeus e S. maculatus revelaram ter alta variabilidade genética intraespecífica. Essas espécies têm, cada uma, pelo menos duas linhagens mitocondriais que, atualmente, ocorrem em simpatria (S. rhombeus) ou alopatria (P. nattereri e S. maculatus). Análises de delimitação de espécies e os altos valores de distância genética observados entre as populações de S. rhombeus e de S. maculatus indicam que cada espécie pode, na verdade, corresponder a um complexo de espécies crípticas. A condição não-monofilética de S. rhombeus e S. maculatus reforça essa hipótese. A distribuição geográfica e o padrão de diferenciação genética observados para as espécies de piranhas analisadas são discutidos com relação aos eventos geológicos e hidrológicos que ocorreram nas bacias hidrográficas.

Molecular characterization and genetic relationships of seven piranha species of the genera Serrasalmus and Pygocentrus (Characiformes: Serrasalmidae) from Paraná-Paraguay, São Francisco and Tocantins River basins in Brazil.

Genetic and phylogenetic relationships among seven piranha species of the genera Serrasalmus and Pygocentrus from the Paraná-Paraguay, São Francisco and Tocantins River basins were evaluated in the present study by partial sequences of two mitochondrial genes, Cytochrome b and Cytochrome c Oxidase I. Phylogenetic analysis of Maximum-Likelihood and Bayesian inference were performed. Results indicated, in general, greater genetic similarity between the two species of Pygocentrus (P. nattereri and P. piraya), between Serrasalmus rhombeus and S. marginatus and between S. maculatus, S. brandtii and S. eigenmanni. Pygocentrus nattereri, S. rhombeus and S. maculatus showed high intraspecific genetic variability. These species have each one, at least two different mitochondrial lineages that, currently, occur in sympatry (S. rhombeus) or in allopatry (P. nattereri and S. maculatus). Species delimitation analysis and the high values of genetic distances observed between populations of S. rhombeus and of S. maculatus indicated that each species may corresponds to a complex of cryptic species. The non-monophyletic condition of S. rhombeus and S. maculatus reinforces the hypothesis. The geographic distribution and the genetic differentiation pattern observed for the piranha species analyzed herein are discussed regarding the geological and hydrological events that occurred in the hydrographic basins.

Molecular characterization and genetic relationships of seven piranha species of the genera Serrasalmus and Pygocentrus (Characiformes: Serrasalmidae) from Paraná-Paraguay, São Francisco and Tocantins River basins in Brazil

Abstract Genetic and phylogenetic relationships among seven piranha species of the genera Serrasalmus and Pygocentrus from the Paraná-Paraguay, São Francisco and Tocantins River basins were evaluated in the present study by partial sequences of two mitochondrial genes, Cytochrome b and Cytochrome c Oxidase I. Phylogenetic analysis of Maximum-Likelihood and Bayesian inference were performed. Results indicated, in general, greater genetic similarity between the two species of Pygocentrus (P. nattereri and P. piraya), between Serrasalmus rhombeus and S. marginatus and between S. maculatus, S. brandtii and S. eigenmanni. Pygocentrus nattereri, S. rhombeus and S. maculatus showed high intraspecific genetic variability. These species have each one, at least two different mitochondrial lineages that, currently, occur in sympatry (S. rhombeus) or in allopatry (P. nattereri and S. maculatus). Species delimitation analysis and the high values of genetic distances observed between populations of S. rhombeus and of S. maculatus indicated that each species may corresponds to a complex of cryptic species. The non-monophyletic condition of S. rhombeus and S. maculatus reinforces the hypothesis. The geographic distribution and the genetic differentiation pattern observed for the piranha species analyzed herein are discussed regarding the geological and hydrological events that occurred in the hydrographic basins.

Resumo Relações genéticas e filogenéticas de sete espécies de piranhas dos gêneros Serrasalmus e Pygocentrus das bacias hidrográficas Paraná-Paraguai, São Francisco e Tocantins foram avaliadas com base em sequências parciais dos genes mitocondriais Citocromo b e Citocromo c Oxidase I. Foram realizadas análises filogenéticas de Máxima Verossimilhança e de inferência Bayesiana. Os resultados indicaram, em geral, maior similaridade genética entre as duas espécies de Pygocentrus (P. nattereri e P. piraya), entre Serrasalmus rhombeus e S. marginatus e entre S. maculatus, S. brandtii e S. eigenmanni. Pygocentrus nattereri, S. rhombeus e S. maculatus revelaram ter alta variabilidade genética intraespecífica. Essas espécies têm, cada uma, pelo menos duas linhagens mitocondriais que, atualmente, ocorrem em simpatria (S. rhombeus) ou alopatria (P. nattereri e S. maculatus). Análises de delimitação de espécies e os altos valores de distância genética observados entre as populações de S. rhombeus e de S. maculatus indicam que cada espécie pode, na verdade, corresponder a um complexo de espécies crípticas. A condição não-monofilética de S. rhombeus e S. maculatus reforça essa hipótese. A distribuição geográfica e o padrão de diferenciação genética observados para as espécies de piranhas analisadas são discutidos com relação aos eventos geológicos e hidrológicos que ocorreram nas bacias hidrográficas.

Genetic divergence among invasive and native populations of Plagioscion squamosissimus (Perciformes, Sciaenidae) in Neotropical regions.

The genetic divergence among invasive and native populations of Plagioscion squamosissimus from four Neotropical hydrographic basins was assessed using the hypervariable domain of the mitochondrial DNA (mtDNA) control region. Plagioscion squamosissimus is native to the neighbouring hydrographic basins of the Parnaíba and Amazon Rivers, and the latter includes the Araguaia-Tocantins drainage, but it is invasive in other basins due to introductions. The mtDNA nucleotide polymorphism supported the hypothesis that the Amazon and Parnaíba populations constitute the same species and are separated into two independent evolutionary lineages. Absence of nucleotide polymorphism was observed within and among P. squamosissimus populations invasive to the uppper and middle Paraná River basins. Nucleotide divergence was null or low comparing the Paraná invasive populations with the populations native to the Parnaíba River basin, whereas it was significantly high compared to Tocantins populations. These results ascertain that P. squamosissimus populations invasive to the upper Paraná River basin and to the middle Paraná River basin downstream of the Itaipu dam are derived from the Parnaíba River basin. The genetic data presented are potentially useful to assist further studies on P. squamosissimus taxonomic and geographic distribution, development of ecological guidelines for managing populations invasive to the upper Paraná River basin and for preservation of native fish diversity.

Molecular differentiation of species of the genus Zungaro (Siluriformes, Pimelodidae) from the Amazon and Paraná-Paraguay River basins in Brazil.

Fish species of the Zungaro genus (Siluriformes, Pimelodidae) are amongst the largest migratory fish in Latin America and have considerable economic importance for commercial fishing in Brazil. However, natural populations of this large catfish are experiencing a severe decline. There are significant taxonomical inconsistencies for this fish. Two geographically separated species of the fish were initially described, one endemic in the Amazon and another in the Paraná-Paraguay River basins. A taxonomic review had recently proposed that there is only one Zungaro species in Brazil, based on morphological data. We made a molecular study of Zungaro populations in an attempt to solve taxonomical inconsistencies and to analyze genetic diversity in natural populations of this genus. We analyzed two regions of the mitochondrial DNA (the control region and the ATPase 6 gene region) of individuals sampled from the Paraná-Paraguay River and Amazon River basins. Analyses based on p-distances and maximum likelihood phylogenetic models showed a genetic difference between populations corresponding to different species. Genetic differentiation between Zungaro populations was at the same level as that observed between other Siluriformes species, using the same DNA sequences. We conclude that Zungaro species of the Paraná-Paraguay River basin do not belong to the same species found in the Amazon basin. This finding has a significant implication for conservation of this fish, given that populations are disappearing at a high rate in the Paraná-Paraguay River basin, mainly due to impoundments.

Heterologous amplification and characterization of microsatellite markers in the Neotropical fish Leporinus friderici.

Leporinus friderici, native to the Amazon Basin and popularly known as "piau-três-pintas", has great ecological and economic importance; it is widely fished and consumed throughout much of tropical South America. Knowledge of the genetic diversity of this native species is important to support management and conservation programs. We evaluated microsatellite loci amplification, using heterologous primers, in 31 individuals of L. friderici. These samples were collected from natural populations of the Araguaia River basin, in central Brazil, and the DNA was extracted from samples of muscle tissue. Eight loci were successfully analyzed. Six of them were polymorphic, and the number of alleles ranged from three to 10. Values of expected heterozygosities for these polymorphic loci ranged from 0.488 to 0.795. Exclusion probability (0.983), the identity probability (0.000073), and the mean genetic diversity values were high, showing that these microsatellite markers are suitable for assessing the genetic variability of L. friderici populations. There is a growing interest in studies that evaluate the genetic variability of natural populations for various purposes, such as conservation. Here, we showed that a viable alternative to the costly development of specific primers for fish populations is simply testing for heterologous amplification of microsatellite markers available from research on other species.

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

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 (pi < 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 x 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.

Genetic divergence between Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Siluriformes: Pimelodidae) in the Paraná River Basin / Divergência genética entre Pseudoplatystoma corruscans e Pseudoplatystoma reticulatum (Pisces; Siluriformes) da Bacia do Rio Paraná

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 x 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 ...

Pseudoplatystoma corruscans Spix e Agassiz, 1829 e Pseudoplatystoma reticulatum Eigenmann e Eigenmann, 1889 são peixes migratórios de grande porte, com alta importância biológica e elevado valor comercial na América do Sul. Híbridos férteis são obtidos em cativeiro e, portanto, é esperada alta proximidade genética entre essas duas espécies de Pimelodidae. Escapes de espécimes híbridos a partir de estações de piscicultura representam um sério problema ambiental. Apesar da sua importância, conhecimentos sobre a biologia, ecologia, diversidade de populações e genética de P. corruscans e P. reticulatum são escassos. No presente trabalho, foi avaliada a divergência genética entre P. corruscans e P. reticulatum da Bacia do Rio Paraná, com base em fragmentos ISSR e na seqüência D-loop do DNA mitocondrial (mtDNA). As estimativas das diversidades intra-específicas haplotípica (h > 0,5) e nucleotídica (π < 0,01) evidenciaram que P. corruscans e P. reticulatum sobreviveram a um declínio populacional histórico, seguido de expansão demográfica. Os polimorfismos interespecíficos no mtDNA e nos fragmentos ISSR foram eficientes para diagnósticos e discriminaram as duas espécies. Um espécime de Pseudoplatystoma capturado na planície de inundação do Alto Rio Paraná foi identificado com esses marcadores moleculares como híbrido P. reticulatum x P. corruscans, que possivelmente escapou de psicicultura. A integridade da população de P. corruscans no Alto Rio Paraná está ameaçada, por introgressão ou homogeneização genética, pela presença de híbridos e pela transposição para montante de P. reticulatum através do Canal da Piracema em Itaipu. Os dados apresentados constituem um avanço na compreensão do parentesco entre P. corruscans e P. reticulatum e representam ferramentas em potencial para programas de conservação biológica, incluindo o monitoramento de introgressão e de integridade genética das populações.