Padrões de migração de Salminus brasiliensis (Characiformes, Characidae, Salmininae) no rio Mogi Guaçu utilizando marcadores genéticos moleculares
Carregando...
Arquivos
Data
2018-03-02
Autores
Alves, Ronald Ribeiro
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os processos migratórios realizados por diferentes espécies animais com finalidades tróficas ou reprodutivas tem despertado grande interesse por parte dos pesquisadores há várias décadas. Entre as espécies de grande importância nestes ambientes, Salminus brasiliensis (Cuvier, 1816) se caracteriza como um peixe migrador de ampla distribuição em território brasileiro, principalmente na bacia do Prata, constituída pelos rios Paraná, Paraguai e Uruguai, onde pode atingir grande tamanho. Assim, estudos que visam proporcionar melhores condições de manejo e sua conservação são muito importantes. Neste contexto, as alterações antropogênicas que afetam a espécie S. brasiliensis e a falta de informação que dificultam estratégias eficazes de manejo e conservação, o presente estudo teve como objetivo investigar a variabilidade genética e a estrutura genética das populações migratórias e residentes de S. brasiliensis da bacia do Rio Mogi Guaçu, a partir de amostragem realizada no período de 2008, 2009, 2010 e 2015, tendo como ferramenta a aplicação de técnicas de genética molecular. Os resultados obtidos indicaram altos níveis de variabilidade genética em todos os grupos amostrados, sendo que a heterozigosidade observada (Ho) variou de 0,59 a 0,67 e a heterozigosidade esperada (He) variou de 0,70 a 0,74. A Análise da Variância Molecular (AMOVA) revelou baixa estruturação genética em todos os grupos (FST = 0,0072), nas quais a maior fonte de variabilidade genética foi verificada entre os indivíduos (85,98%). No entanto, a análise de FST em pares mostrou diferenças sutis na variabilidade genética, uma vez que foi verificada uma variação de FST = 0,025; p <0,05 entre os grupos residentes (2008/2015) e de FST = 0,026; p <0,05 entre os grupos migratórios (2009/2010) e o grupo residente (2015). Embora os estoques analisados desta espécie apresentem altos níveis de variabilidade genética, por conta do número de alelos, não pode ser descartada a possibilidade de que mudanças ambientais possam afetar essa variabilidade genética existente. Assim, a possibilidade de uma redução populacional não pode ser excluída devido à perda de alelos e ao aumento da pressão seletiva, em decorrência da instalação de novos projetos nestes ambientes e caso venham a interferir negativamente na dinâmica reprodutiva da espécie, poderá ocorrer a perda do fluxo gênico, com consequente aumento da endogamia, fatores que são prejudiciais ao equilíbrio genético populacional. Neste sentido, considera-se que estudos aprofundados e continuados sobre a estrutura e a dinâmica das populações desta espécie são necessários neste ambiente, visando adicionar informações que possam estimar e prever condições para sua sustentação, podendo, do mesmo modo, contribuir, assim, para a conservação de outras espécies de peixes deste ecossistema.
The migratory processes carried out by different animal species for trophic or reproductive purposes have aroused great interest on the part of researchers for several decades. Among the species of great importance in these environments, Salminus brasiliensis (Cuvier, 1816) is characterized as a migratory fish of wide distribution in Brazilian territory, mainly in the Prata basin, constituted by the rivers Paraná, Paraguay and Uruguay, where it can reach large size. Thus, studies aimed at providing better management conditions and its conservation is important and well received. In this context, considering the anthropogenic changes that affect the S. brasiliensis species and the lack of information that allow effective management and conservation strategies, this study aimed to investigate the genetic variability and genetic structure of the migratory and resident populations of S. brasiliensis from the Mogi Guaçu River basin, based on sampling carried out from 2008 to 2015 using as a tool the application of molecular genetic techniques. The results indicated high levels of genetic variability in all the sampled groups and the observed heterozygosity (Ho) varied from 0.59 to 0.67 while the expected heterozygosity (He) ranged from 0.70 to 0.74. Molecular Variance Analysis (AMOVA) revealed low genetic structure in all groups analyzed (FST = 0.0072), in which the greatest source of genetic variability was observed in comparisons among individuals (85.98%). However, the analysis of FST in pairs showed subtle differences in genetic variability, since it was found a variation of FST = 0.025; P <0.05 between the resident groups (2008/2015), and of FST = 0.026; P <0.05 between the migratory groups (2009/2010) and the resident group (2015). Although the analyzed stocks of this species showed high levels of genetic variability, the possibility that environmental changes can affect this genetic variability cannot be ruled out. Thus, the possibility of a population reduction cannot be excluded due to loss of alleles and selective pressure increase, due to the installation of new projects in these environments. These facts certainly will negatively interfere in the reproductive dynamics of the species, gene flow, with a consequent increase in inbreeding, factors that are detrimental to the population genetic balance. In this sense, it is considered that in-depth and continuous studies on the structure and dynamics of the populations of this species are necessary in this environment, aiming at adding information that can estimate and predict conditions for being able its sustentation, and in the same way contributing to the conservation of other species in the ecosystem.
The migratory processes carried out by different animal species for trophic or reproductive purposes have aroused great interest on the part of researchers for several decades. Among the species of great importance in these environments, Salminus brasiliensis (Cuvier, 1816) is characterized as a migratory fish of wide distribution in Brazilian territory, mainly in the Prata basin, constituted by the rivers Paraná, Paraguay and Uruguay, where it can reach large size. Thus, studies aimed at providing better management conditions and its conservation is important and well received. In this context, considering the anthropogenic changes that affect the S. brasiliensis species and the lack of information that allow effective management and conservation strategies, this study aimed to investigate the genetic variability and genetic structure of the migratory and resident populations of S. brasiliensis from the Mogi Guaçu River basin, based on sampling carried out from 2008 to 2015 using as a tool the application of molecular genetic techniques. The results indicated high levels of genetic variability in all the sampled groups and the observed heterozygosity (Ho) varied from 0.59 to 0.67 while the expected heterozygosity (He) ranged from 0.70 to 0.74. Molecular Variance Analysis (AMOVA) revealed low genetic structure in all groups analyzed (FST = 0.0072), in which the greatest source of genetic variability was observed in comparisons among individuals (85.98%). However, the analysis of FST in pairs showed subtle differences in genetic variability, since it was found a variation of FST = 0.025; P <0.05 between the resident groups (2008/2015), and of FST = 0.026; P <0.05 between the migratory groups (2009/2010) and the resident group (2015). Although the analyzed stocks of this species showed high levels of genetic variability, the possibility that environmental changes can affect this genetic variability cannot be ruled out. Thus, the possibility of a population reduction cannot be excluded due to loss of alleles and selective pressure increase, due to the installation of new projects in these environments. These facts certainly will negatively interfere in the reproductive dynamics of the species, gene flow, with a consequent increase in inbreeding, factors that are detrimental to the population genetic balance. In this sense, it is considered that in-depth and continuous studies on the structure and dynamics of the populations of this species are necessary in this environment, aiming at adding information that can estimate and predict conditions for being able its sustentation, and in the same way contributing to the conservation of other species in the ecosystem.
Descrição
Palavras-chave
microssatélites, Salminus brasiliensis, marcadores moleculares, migração, Mogi Guaçu