Identificação de SNPs e genética populacional de cardumes migradores e residentes de Prochilodus lineatus (Characiformes: Prochilodontidae)
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2022-07-29
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Universidade Estadual Paulista (Unesp)
Resumo
O conhecimento acerca da dinâmica e biologia de espécies de peixes migradores é essencial para a manutenção da diversidade genética. Uma das espécies mais frequentes no ambiente neotropical é Prochilodus lineatus, popularmente conhecida como curimbatá. Considerado um peixe migrador de longas distâncias, P. lineatus compõe extensos cardumes que migram nos rios da bacia do Alto Paraná durante a piracema. Cardumes de curimbatás residentes vem sendo observados, sendo os peixes que deixam de migrar e se estabelecem em uma região, dando indícios de uma possível existência de estoques geneticamente distintos. Considerando a importância das espécies migradoras para o ecossistema, o objetivo desse trabalho foi desenvolver marcadores moleculares do tipo SNPs (Polimorfismo de nucleotídeo único) para P. lineatus e aplicá-los através de metodologias de genética populacional em cardumes migradores e residentes para identificar a possível existência de estruturação e analisar a variabilidade genética nestes grupos biológicos. Para tal, utilizou-se a tecnologia RAD de dupla digestão (ddRAD-seq) em 80 amostras de curimbatás coletados no Rio Mogi-Guaçu, na região da Cachoeira de Emas, SP, sendo analisados 10 indivíduos migradores e 10 residentes capturados a cada ano (2008, 2009, 2010 e 2021). Ao final da extração de DNA, elaboração das bibliotecas e sequenciamento, as filtragens resultaram em 4.085 SNPs que foram utilizados em análises populacionais. Para todos os anos, os valores de heterozigosidade observada (HO) e da heterozigosidade esperada (HE) foram semelhantes e os valores de HWE indicaram um excesso de homozigotos. Os valores de FIS, positivos e significativos, indicaram um tênue nível de endogamia nos grupos analisados. Os valores de FST indicaram a existência de agrupamentos entre os residentes de 2008 e 2021, enquanto os migradores demonstraram uma maior homogeneização de clusters. O AMOVA indicou a maior diferenciação entre indivíduos dentro das populações, mas uma significativa diferenciação entre grupos. Sendo assim, é possível concluir que os grupos de migradores permanecem com fluxo gênico, enquanto o de residentes podem estar apresentando um início de processo de estruturação, que poderá ser evidenciado ao longo dos próximos anos com a queda do número efetivo populacional, fazendo com que seja necessário o monitoramento dos curimbatás do rio Mogi-Guaçu para que não haja perca da variabilidade genética nos cardumes.
Knowledge about the dynamics and biology of migratory fish species is essential for the maintenance of genetic diversity. One of the most frequent species in the neotropical environment is Prochilodus lineatus, popularly known as curimbatá. Considered a long-distance migratory fish, P. lineatus makes up extensive shoals that migrate in the rivers of the Upper Paraná basin during spawning. Shoals of resident curimbatás have been observed, with fish that stop migrating and settle in a region, indicating the possible existence of genetically distinct stocks. Considering the importance of migratory species to the ecosystem, the objective of this work was to develop SNPs (Single Nucleotide Polymorphism) molecular markers for P. lineatus and apply them through population genetics methodologies in migratory and resident schools to identify the possible existence of structuring and to analyze the genetic variability in these biological groups. For this, the double digestion RAD technology (ddRAD-seq) was used in 80 samples of curimbatás collected in the Mogi-Guaçu River, in the region of Cachoeira de Emas, SP, being analyzed 10 migratory individuals and 10 residents captured each year (2008, 2009, 2010 and 2021). At the end of DNA extraction, elaboration of libraries and sequencing, the filters resulted in 4085 SNPs that were used in population analyses. For all years, observed heterozygosity (HO) and expected heterozygosity (HE) values were similar, and HWE values indicated an excess of homozygotes. The FIS values were positive and significant, indicating a low level of inbreeding in the analyzed groups. The FST values indicated the existence of clusters between the residents of 2008 and 2021, while the migrants showed a greater homogenization of clusters. AMOVA indicated the greatest differentiation between individuals within populations, but a significant differentiation between groups. Therefore, it is possible to conclude that the migratory groups remain with gene flow, while the resident groups may be showing the beginning of a structuring process, which may be evidenced over the next few years with the drop in the effective population number, causing it is necessary to monitor the curimbatás of the Mogi-Guaçu river so that there is no loss of genetic variability in the shoals.
Knowledge about the dynamics and biology of migratory fish species is essential for the maintenance of genetic diversity. One of the most frequent species in the neotropical environment is Prochilodus lineatus, popularly known as curimbatá. Considered a long-distance migratory fish, P. lineatus makes up extensive shoals that migrate in the rivers of the Upper Paraná basin during spawning. Shoals of resident curimbatás have been observed, with fish that stop migrating and settle in a region, indicating the possible existence of genetically distinct stocks. Considering the importance of migratory species to the ecosystem, the objective of this work was to develop SNPs (Single Nucleotide Polymorphism) molecular markers for P. lineatus and apply them through population genetics methodologies in migratory and resident schools to identify the possible existence of structuring and to analyze the genetic variability in these biological groups. For this, the double digestion RAD technology (ddRAD-seq) was used in 80 samples of curimbatás collected in the Mogi-Guaçu River, in the region of Cachoeira de Emas, SP, being analyzed 10 migratory individuals and 10 residents captured each year (2008, 2009, 2010 and 2021). At the end of DNA extraction, elaboration of libraries and sequencing, the filters resulted in 4085 SNPs that were used in population analyses. For all years, observed heterozygosity (HO) and expected heterozygosity (HE) values were similar, and HWE values indicated an excess of homozygotes. The FIS values were positive and significant, indicating a low level of inbreeding in the analyzed groups. The FST values indicated the existence of clusters between the residents of 2008 and 2021, while the migrants showed a greater homogenization of clusters. AMOVA indicated the greatest differentiation between individuals within populations, but a significant differentiation between groups. Therefore, it is possible to conclude that the migratory groups remain with gene flow, while the resident groups may be showing the beginning of a structuring process, which may be evidenced over the next few years with the drop in the effective population number, causing it is necessary to monitor the curimbatás of the Mogi-Guaçu river so that there is no loss of genetic variability in the shoals.
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Mogi-Guaçu, Curimbatá, SNPs, Migradores e residentes, Genética animal, Rio Mogi-Guaçu, Prochilodus lineatus