Identificação molecular de tubarões e raias da costa brasileira: uso do DNA Barcode na conservação de recursos genéticos
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Data
2022-02-25
Autores
Ribeiro, Giovana da Silva
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Universidade Estadual Paulista (Unesp)
Resumo
Os tubarões e raias, organismos que compõem a infraclasse Elasmobranchii, são peixes cartilaginosos que são representados no Brasil por 163 espécies descritas. Geralmente são caracterizados por apresentarem particularidades biológicas como crescimento lento, maturidade tardia e baixa fecundidade, tornando essas espécies sensíveis a efeitos antrópicos. Aproximadamente 32,5% dessas espécies estão sob ameaça e isto ocorre principalmente devido a fatores como perda de habitat e sobrepesca. Algumas espécies de tubarões e raias se enquadram em um grupo biológico de difícil identificação taxonômica, principalmente envolvendo espécies congêneres que podem apresentar características morfológicas similares e com isso, apresentam inconsistências na identificação. O uso da ferramenta molecular de análise pelo DNA Barcode possibilitou a construção de um banco de dados, gerando um sistema global para a bioidentificação das espécies. Considerando o déficit de dados genéticos e de informações sobre a biodiversidade dos Elasmobranchii encontrados na costa do Brasil, o presente estudo teve como objetivo principal a identificação molecular dos integrantes deste grupo. Foram utilizadas 240 amostras de tubarões e raias coletados em diferentes localidades da costa brasileira que se encontram depositadas na coleção do Laboratório de Biologia e Genética de Peixes. Os resultados das análises utilizando o gene mitocondrial COI, permitiram a identificação molecular de representantes de 20 espécies de tubarões pertencentes às famílias Carcharhinidae (n = 51), Sphyrnidae (n = 11), Squalidae (n = 44), e Squatinidae (n = 1); e mais 10 espécies de raias pertencentes às famílias Aetobatidae (n = 3), Dasyatidae (n = 45), Gymnuridae (n = 3), Mobulidae (n = 1), Rhinopteridae (n = 32), Arhynchobatidae (n = 1), Rhinobatidae (n = 18). As análises realizadas permitiram determinar as distâncias interespecíficas entre tubarões, com valores de 3,7% entre as espécies Carcharhinus brevipinna e Carcharhinus obscurus e também entre Centrophorus granulosus e Centrophorus squamosus, com a maior distância de 29,8% observada entre C. squamosus e Isurus oxyrinchus. Os valores de distâncias genéticas intraespecíficas variaram entre 0 a 0,90%, sendo que o maior valor encontrado para a espécie I. oxyrinchus. Entre as raias, as distâncias genéticas interespecíficas variaram de 5,4% entre as espécies Fontitrygon geijskesi e Hypanus guttatus a 28,3% entre Pseudobatos horkelii e Aetobatus narinari, enquanto as distâncias genéticas intraespecíficas revelaram valores entre 0,10% para Atlantoraja castelnaui e Hypanus guttatus e o maior valor encontrado foi de 0,80% para a espécie Dasyatis sp. Entre todas as 30 espécies de tubarões e raias analisadas verificou-se que 22 estão inseridas em alguma classificação de ameaça segundo a Lista Vermelha de animais ameaçados da IUCN, sendo cinco classificadas no item “vulnerável”, 11 classificadas “em perigo” e seis como “criticamente ameaçadas”. Dado que as sequências de DNA Barcode obtidas serão disponibilizadas no banco de dados genômicos após a finalização do presente trabalho, considera-se que as informações aqui apresentadas poderão oferecer suporte confiável para futuras pesquisas populacionais e elaboração de estratégias de conservação nesse importante grupo de organismos.
Sharks and rays, organisms whom compose the Elasmobranchii infraclass, are cartilaginous fish that are represented in Brazil by 163 described species. They are usually characterized by presenting biological peculiarities such as slow growth, late maturity and low fecundity, making these species sensitive to anthropic effects. Approximately 32.5% of these species are under threatened and this is mainly due to factors such as habitat loss and overfishing. Some species of sharks and rays fall within a biological group of difficult taxonomic identification, mainly involving congeners species that may present similar morphological characteristics and, therefore, present inconsistencies in the identification. The use of the molecular analysis tool by DNA Barcode enabled the construction of a database, generating a global system for the bioidentification of species. Considering the deficit of genetic data and information about the biodiversity of Elasmobranchii found off the coast of Brazil, the present study has as its main objective the molecular identification of the members of this group. We used 240 samples of sharks and rays collected in different locations along the Brazilian coast, which are deposited in the collection of the Laboratory of Biology and Genetics of Fish. The analysis results, using the mitochondrial gene COI, allowed the molecular identification of representatives of 20 species of sharks belonging to the families Carcharhinidae (n = 51), Sphyrnidae (n = 11), Squalidae (n = 44), and Squatinidae (n = 1); and 10 more species of rays belonging to the families Aetobatidae (n = 3), Dasyatidae (n = 45), Gymnuridae (n = 3), Mobulidae (n = 1), Rhinopteridae (n = 32), Arhynchobatidae (n = 1), Rhinobatidae (n = 18). The analyzes performed allowed us to determine the interspecific distances between sharks, with values of 3.7% between the species Carcharhinus brevipinna and Carcharhinus obscurus and also between Centrophorus granulosus and Centrophorus squamosus, with the greatest distance of 29.8% observed between C. squamosus and Isurus oxyrinchus. The values of intraspecific genetic distances ranged from 0 to 0.90%, with the highest value found for the species I. oxyrinchus. Among rays, interspecific genetic distances ranged from 5.4% between Fontitrygon geijskesi and Hypanus guttatus to 28.3% between Pseudobatos horkelii and Aetobatus narinari, while intraspecific genetic distances revealed values between 0.10% for Atlantoraja castelnaui and Hypanus guttatus and the highest value found was 0.80% for the species Dasyatis sp . Among all 30 species of sharks and rays analyzed, it was found that 22 are included in some threat classification according to the IUCN Red List of Threatened Animals, with five classified as “vulnerable”, 11 classified as “endangered” and six as endangered. “critically endangered”. Given that the DNA Barcode sequences obtained will be made available in the genomic database after the completion of the present work, it is considered that the information presented here can provide reliable support for future population research and the elaboration of conservation strategies in this important group of organisms.
Sharks and rays, organisms whom compose the Elasmobranchii infraclass, are cartilaginous fish that are represented in Brazil by 163 described species. They are usually characterized by presenting biological peculiarities such as slow growth, late maturity and low fecundity, making these species sensitive to anthropic effects. Approximately 32.5% of these species are under threatened and this is mainly due to factors such as habitat loss and overfishing. Some species of sharks and rays fall within a biological group of difficult taxonomic identification, mainly involving congeners species that may present similar morphological characteristics and, therefore, present inconsistencies in the identification. The use of the molecular analysis tool by DNA Barcode enabled the construction of a database, generating a global system for the bioidentification of species. Considering the deficit of genetic data and information about the biodiversity of Elasmobranchii found off the coast of Brazil, the present study has as its main objective the molecular identification of the members of this group. We used 240 samples of sharks and rays collected in different locations along the Brazilian coast, which are deposited in the collection of the Laboratory of Biology and Genetics of Fish. The analysis results, using the mitochondrial gene COI, allowed the molecular identification of representatives of 20 species of sharks belonging to the families Carcharhinidae (n = 51), Sphyrnidae (n = 11), Squalidae (n = 44), and Squatinidae (n = 1); and 10 more species of rays belonging to the families Aetobatidae (n = 3), Dasyatidae (n = 45), Gymnuridae (n = 3), Mobulidae (n = 1), Rhinopteridae (n = 32), Arhynchobatidae (n = 1), Rhinobatidae (n = 18). The analyzes performed allowed us to determine the interspecific distances between sharks, with values of 3.7% between the species Carcharhinus brevipinna and Carcharhinus obscurus and also between Centrophorus granulosus and Centrophorus squamosus, with the greatest distance of 29.8% observed between C. squamosus and Isurus oxyrinchus. The values of intraspecific genetic distances ranged from 0 to 0.90%, with the highest value found for the species I. oxyrinchus. Among rays, interspecific genetic distances ranged from 5.4% between Fontitrygon geijskesi and Hypanus guttatus to 28.3% between Pseudobatos horkelii and Aetobatus narinari, while intraspecific genetic distances revealed values between 0.10% for Atlantoraja castelnaui and Hypanus guttatus and the highest value found was 0.80% for the species Dasyatis sp . Among all 30 species of sharks and rays analyzed, it was found that 22 are included in some threat classification according to the IUCN Red List of Threatened Animals, with five classified as “vulnerable”, 11 classified as “endangered” and six as endangered. “critically endangered”. Given that the DNA Barcode sequences obtained will be made available in the genomic database after the completion of the present work, it is considered that the information presented here can provide reliable support for future population research and the elaboration of conservation strategies in this important group of organisms.
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Palavras-chave
Biodiversidade - Conservação, COI, Elasmobrânquios, Tubarão (Peixe)