Análise genética da reposição de estoques de peixes na bacia do rio Sapucaí-Mirim (SP): Implicações na conservação
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2018-07-27
Autores
Mendonça, Bruna Bueno [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Múltiplos fatores antropogênicos têm causado grande interferência nos ecossistemas aquáticos continentais, entre eles estão os represamentos dos rios. As alterações causadas por essas construções afetam profundamente populações de peixes, podendo levar até mesmo a extinção das espécies que não apresentam adaptação às alterações provocadas nestes ecossistemas. Assim, ação como o repovoamento através do supportive breeding tem sido empregada a fim de manter populações naturais vulneráveis. Porém, no Brasil, poucos trabalhos de soltura de alevinos levam em conta características genéticas para a formação dos estoques de reprodutores. Além disso, poucos trabalhos de repovoamento se preocupam com a eficiência destes, não havendo monitoramento da diversidade genética dos indivíduos liberados pós-soltura. O presente estudo empregou loci microssatélites a fim de acessar a diversidade e estrutura genética de populações de Astyanax altiparanae em Pequenas Centrais Hidrelétricas (PCHs), no rio Sapucaí-Mirim de 2015 a 2017, onde ocorre soltura de alevinos desde 2011. Além disso, foi proposto o uso de marcadores microssatélites, como ferramentas para auxiliar na formação de banco de reprodutores e estimar o índice de recaptura de indivíduos provenientes de estoques de cultivo provenientes de repovoamentos em populações naturais. Os bancos de reprodutores analisados dos anos de 2015 e 2016 mostram que os indivíduos que compõem esse banco apresentam alta diversidade genética (A = 24, 35; AR = 16,27; HE = 0,856), com valores do índice de fixação (Fis) variando de 0,146 a 0,207 (P-value = 0, 007). O estoque de 2015 apresentou desvios significativos do equilíbrio de Hardy-Weinberg para a maioria dos loci. Isto sugere junto com os valores do Fis, que este estoque pode apresentar indivíduos pertencentes a diferentes populações, o que indica necessidade da distinção dos reprodutores de acordo com cada PCH respeitando essa diferenciação genética. As analises das diferentes populações da natureza ao longo do ano de 2015 a 2017 também revelaram alta diversidade genética (A = 23,26, AR = 11,78, HE = 0,918), não mostrando diminuição destes índices ao decorrer dos anos. Os valores de Fis variaram de 0,120 a 0,225 (P-value = 0, 007) e os valores de estruturação genética (Fst) variaram de 0 a 0, 023 (P-value = 0,0018). As análises de diversidade genética somada e as de estruturação sugerem que estas populações podem estar sendo homogeneizadas pela soltura de indivíduos provenientes do mesmo estoque. Além disso, os microssatélites se mostraram ferramentas eficientes para o monitoramento de estoques de reprodutores bem como para a estimativa de recaptura em solturas do rio Sapucaí-Mirim, demonstrando recaptura de 0,19 a 0,79%. Desta forma, o presente trabalho demonstra a importância do uso de marcadores moleculares, como os microssatélites, na estimativa da diversidade genética e dos níveis de parentesco em programas de repovoamento a fim de propor o manejo adequado das diferentes populações e identificar os efeitos destes programas.
Multiple anthropogenic factors have caused great interference in continental aquatic ecosystems, among them are the impoundments of the rivers. The changes caused by these constructions deeply affect fish populations and may lead to extinction of species that do not have adaptation to changes in these ecosystems. Thus, actions like the fish stocking through the supportive breeding have been employed in order to maintain vulnerable wild populations. However, in Brazil, few restocking programs take into account genetics characteristics for the foundation of breeding stocks. In addition, scarce studies are concerned with their efficiency, and there are not monitoring of the genetic diversity post release of the fingerlings. This work employed loci microsatellite aiming access the diversity and genetic structure of Astyanax lacustris populations in Small Hydroelectric Plants (SHP), in the Sapucaí-Mirim River from 2015 to 2017, where there are releases since 2011. Additionally, it was proposed the use of microsatellites markers as tool to assist in the foundation of breeders stocks and estimate the recapture rate of individuals from breeding of fish farm stocks. The breeders analyzed from the years 2015 and 2016 show that individual that make up this stock show high genetic diversity (A = 24.35; AR = 16.27; HE = 0.856), with values of index (Fis) ranging from 0.146 to 0.207 (P-value = 0.007). The stock of 2015 presented significant deviations from Hardy-Weinberg equilibrium for most loci. This suggests, along with the Fis values, which this stock may present individuals belonging to different populations, indicating need for distinctions of breeders according with each SHP, respecting this genetic differentiation. The analysis of different wild populations throughout the year from 2015 to 2017 also revealed high genetic diversity (A = 23.26, AR = 11.78, HE = 0.918), it is not show a decrease of these indexes to over the years. Fis values ranged from 0.120 to 0.225 (P-value = 0.007) and structuring values (Fst) ranged from 0 to 0.023 (P-value = 0.0018). Analyses of genetic diversity coupled with genetic structure suggest that these populations may be homogenized by the release of individuals from the same stock. Besides that, the microsatellites markers were powerful tool for the breeding stocks monitoring as well as for the estimation of recaptures in releases in the Sapucaí-Mirim River, demonstrating recapture of 0.19% to 0.79%. Therefore, the present study demonstrates the importance of using molecular markers, such microsatellites, in the evaluation of genetic diversity and levels of relatedness in supportive breeding programs in order to propose the proper management of different populations and identify the effects of these programs
Multiple anthropogenic factors have caused great interference in continental aquatic ecosystems, among them are the impoundments of the rivers. The changes caused by these constructions deeply affect fish populations and may lead to extinction of species that do not have adaptation to changes in these ecosystems. Thus, actions like the fish stocking through the supportive breeding have been employed in order to maintain vulnerable wild populations. However, in Brazil, few restocking programs take into account genetics characteristics for the foundation of breeding stocks. In addition, scarce studies are concerned with their efficiency, and there are not monitoring of the genetic diversity post release of the fingerlings. This work employed loci microsatellite aiming access the diversity and genetic structure of Astyanax lacustris populations in Small Hydroelectric Plants (SHP), in the Sapucaí-Mirim River from 2015 to 2017, where there are releases since 2011. Additionally, it was proposed the use of microsatellites markers as tool to assist in the foundation of breeders stocks and estimate the recapture rate of individuals from breeding of fish farm stocks. The breeders analyzed from the years 2015 and 2016 show that individual that make up this stock show high genetic diversity (A = 24.35; AR = 16.27; HE = 0.856), with values of index (Fis) ranging from 0.146 to 0.207 (P-value = 0.007). The stock of 2015 presented significant deviations from Hardy-Weinberg equilibrium for most loci. This suggests, along with the Fis values, which this stock may present individuals belonging to different populations, indicating need for distinctions of breeders according with each SHP, respecting this genetic differentiation. The analysis of different wild populations throughout the year from 2015 to 2017 also revealed high genetic diversity (A = 23.26, AR = 11.78, HE = 0.918), it is not show a decrease of these indexes to over the years. Fis values ranged from 0.120 to 0.225 (P-value = 0.007) and structuring values (Fst) ranged from 0 to 0.023 (P-value = 0.0018). Analyses of genetic diversity coupled with genetic structure suggest that these populations may be homogenized by the release of individuals from the same stock. Besides that, the microsatellites markers were powerful tool for the breeding stocks monitoring as well as for the estimation of recaptures in releases in the Sapucaí-Mirim River, demonstrating recapture of 0.19% to 0.79%. Therefore, the present study demonstrates the importance of using molecular markers, such microsatellites, in the evaluation of genetic diversity and levels of relatedness in supportive breeding programs in order to propose the proper management of different populations and identify the effects of these programs
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Palavras-chave
marcadores microssatélites, Astyanax altiparanae, Conservação genética, Repovoamentos