Análise comparativa da composição genética de exemplares da fauna de peixes marinho-estuarinos encontrados na costa do Brasil
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Data
2018-02-22
Autores
Cerqueira, Najila Nolie Catarine Dantas
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Universidade Estadual Paulista (Unesp)
Resumo
A elevada biodiversidade da ictiofauna marinha no oceano Atlântico do litoral do Brasil resulta num desafio para os estudos de especiação. As barreiras biogeográficas influenciam grandemente o isolamento genético de algumas espécies marinhas, porém a eficácia da transposição dessas barreiras, por alguns peixes podem ocorrer, fazendo com que não haja alterações no fluxo gênico das espécies. No entanto, poucos são os estudos realizados com a ictiofauna marinha em relação aos padrões zoogeógrafos e a rica biodiversidade íctica que se encontra no litoral do Brasil. Considerando o exposto, em nosso trabalho de pesquisa, utilizamos a ferramenta DNA barcoding com objetivo de testar a hipótese da existência de barreiras entre as 10 espécies de peixes que apresenta diferentes hábitos de vida, em áreas geográficas com condições ambientais distintas na costa do Brasil que gerem um isolamento a nível populacional ou especifico e contribuir na formação de um banco de tecido de espécies de peixes marinho-estuarinos. Os fragmentos de DNA barcode com cerca de 600 pares de bases do Citocromo Oxidase C subunidade 1 (COI), foram amplificados por PCR e sequenciados para 145 indivíduos. A análise de divergência genética observada nos espécimes Chaetodipterus faber, Hemicaranx amblyrhynchus, Selene vomer e Nebris microps apresentaram valores intraespecífico menor que 2%, sugerindo que estas espécies adotam uma única unidade evolutiva (U.E) Provavelmente essas espécies não apresentaram diferenciação genética, devido sua capacidade em transpor as barreiras marinhas existentes ao longo da costa da América do Sul, como a pluma Amazonas-Orinoco. Em contrapartida para as espécies: Conodon nobilis, Haemulon aurolineatum, Trachinotus carolinus e Sphoeroides testudineus, a pluma do Amazonas-Orinoco ocasionou isolamento genético entre as populações da América do Norte e América do Sul. A espécie Lobotes surinamensis divergiu 3% na comparação entre os indivíduos do Atlântico e do Pacífico, resultando em duas espécies provavelmente separadas quando da formação do Istmo do Panamá. Para a espécie Orthopristis ruber da região Norte/Nordeste a divergência variou entre 3,4 % a 3,7% em relação aos indivíduos da região Sudeste/Sul do litoral do Brasil sugerindo a ocorrência de duas espécies na região Norte e Sul do Brasil, certamente separadas pelo desague da pluma do Rio São Francisco no Atlântico e pelas correntes oceânicas.
The high biodiversity of the marine ichthyofauna in the Atlantic Ocean of the Brazilian coast results in a challenge for the studies of speciation. Biogeographic barriers greatly influence the genetic isolation of some marine species, but the effectiveness of transposition of these barriers by some fish may occur so that there is no change in the gene flow of the species. However, few studies have been carried out with the marine ichthyofauna in relation to the zoogeograph standards and the rich fish biodiversity that is found in the Brazilian coast. Considering the above, in our research work, we used the DNA barcode tool to study 10 species of fish that presents different habits of life, in geographic areas with distinct environmental conditions in the Brazilian coast that generate isolation at the population or specific level and contribute to the formation of a tissue bank of marine-estuarine fish species. In addition to comparing the sequences generated for different areas of the coast of Brazil. DNA barcode fragments with about 600 base pairs of the Cytochrome Oxidase C subunit 1 (COI) were amplified by PCR and sequenced to 145 individuals. The Neighbor-Joining analysis revealed that four species presented a single evolutionary unit in the studied area: Chaetodipterus faber, Hemicaranx amblyrhynchus, Selene vomer, and Nebris microps, presenting genetic distance inferior to 2%. Probably these species do not present genetic differentiation due to their ability to cross the existing marine barriers along the coast of South America, such as the Amazon-Orinoco plume. In contrast to the species: Conodon nobilis, Haemulon aurolineatum, Trachinotus carolinus, and Sphoeroides testudineus, the Amazon-Orinoco plume caused genetic isolation between the populations of North America and South America. The species Lobotes surinamensis diverged 3% in the comparison between individuals from the Atlantic and Pacific, resulting in two species separated when the Isthmus of Panama was formed. For Orthopristis ruber of the North/Northeast region the divergence ranged from 3.4% to 3.7% in relation to the individuals from the Southeast/South region of the Brazilian coast suggesting the occurrence of two species, in the North and South of Brazil, certainly separated by the drainage of the plume of the São Francisco River in the Atlantic and by the ocean currents.
The high biodiversity of the marine ichthyofauna in the Atlantic Ocean of the Brazilian coast results in a challenge for the studies of speciation. Biogeographic barriers greatly influence the genetic isolation of some marine species, but the effectiveness of transposition of these barriers by some fish may occur so that there is no change in the gene flow of the species. However, few studies have been carried out with the marine ichthyofauna in relation to the zoogeograph standards and the rich fish biodiversity that is found in the Brazilian coast. Considering the above, in our research work, we used the DNA barcode tool to study 10 species of fish that presents different habits of life, in geographic areas with distinct environmental conditions in the Brazilian coast that generate isolation at the population or specific level and contribute to the formation of a tissue bank of marine-estuarine fish species. In addition to comparing the sequences generated for different areas of the coast of Brazil. DNA barcode fragments with about 600 base pairs of the Cytochrome Oxidase C subunit 1 (COI) were amplified by PCR and sequenced to 145 individuals. The Neighbor-Joining analysis revealed that four species presented a single evolutionary unit in the studied area: Chaetodipterus faber, Hemicaranx amblyrhynchus, Selene vomer, and Nebris microps, presenting genetic distance inferior to 2%. Probably these species do not present genetic differentiation due to their ability to cross the existing marine barriers along the coast of South America, such as the Amazon-Orinoco plume. In contrast to the species: Conodon nobilis, Haemulon aurolineatum, Trachinotus carolinus, and Sphoeroides testudineus, the Amazon-Orinoco plume caused genetic isolation between the populations of North America and South America. The species Lobotes surinamensis diverged 3% in the comparison between individuals from the Atlantic and Pacific, resulting in two species separated when the Isthmus of Panama was formed. For Orthopristis ruber of the North/Northeast region the divergence ranged from 3.4% to 3.7% in relation to the individuals from the Southeast/South region of the Brazilian coast suggesting the occurrence of two species, in the North and South of Brazil, certainly separated by the drainage of the plume of the São Francisco River in the Atlantic and by the ocean currents.
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Palavras-chave
COI, DNA barcoding, barreiras biogeográficas