Diversidade genética e análise de parentesco em tubarões da espécie Squalus acanthias (Chondrichthyes: Squalidae) no oceano Atlântico, por meio de SNPs
Carregando...
Data
2022-02-10
Autores
Boza, Beatriz Rochitti
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A pesca excessiva influencia em mudanças na estratégia de vida das populações dos organismos aquáticos, especialmente dos elasmobrânquios (tubarões e raias). O conhecimento e identificação de estoques das populações representam um ponto fundamental para o manejo e conservação das espécies. A espécie Squalus acanthias é um tubarão de pequeno porte, pertencente ao gênero Squalus, popularmente conhecido como cação-bagre-espinhoso, amplamente distribuído, migrador e susceptível à sobrepesca. Na Argentina, há uma alta ocorrência de pesca sobre S. acanthias, que atualmente recebe a classificação Vulnerável (VU) na lista vermelha da IUCN (União Internacional para Conservação da Natureza). Neste contexto, o presente trabalho teve como objetivos estudar amostras de S. acanthias, procurando rastrear marcadores SNPs para estudos populacionais e parentesco, estudar a composição genética de uma população e a ocorrência de paternidade múltipla. A biblioteca ddRADSeq foi realizada com fêmeas e seis ninhadas, variando de três a 12 filhotes/mãe, totalizando 40 amostras de Mar del Plata (n=17) e Puerto de Santa Cruz (n=23), Argentina. Após o sequenciamento, foi realizado o rastreio de marcadores, resultando em 4.157 SNPs. Os índices de diversidade genética foram moderados (para heterosigozidade observada e heterozigosidade esperada), além disso, o coeficiente de endogamia (FIS) foi negativo para ambas as localidades analisadas, indicando um excesso de heterozigotos e ausência de endogamia. O FST pairwise foi de 0.042 entre as regiões de Mar del Plata e Puerto de Santa Cruz, demonstrando ausência de estruturação populacional. As análises com os programas STRUCTURE e DAPC indicaram que os indivíduos analisados estão distribuídos em três clusters genéticos, além disso, foi encontrado um alto fluxo gênico entre os indivíduos das diferentes localidades, porém apresentando baixo tamanho efetivo populacional (Ne). As análises de parentesco revelaram indivíduos bem relacionados geneticamente. No programa COLONY foram identificadas 35 relações de irmãos completos, distribuídos em oito grupos que variaram em tamanho de dois a cinco indivíduos, e 45 relações de meio-irmãos, e a paternidade múltipla foi detectada em três das seis ninhadas analisadas. Este é o primeiro estudo que avaliou a diversidade genética, estruturação populacional e paternidade múltipla na espécie S. acanthias na costa da Argentina com marcadores SNPs. Os resultados obtidos apresentam evidências da ocorrência de uma única unidade panmítica na costa da Argentina e ocorrência de paternidade múltipla na espécie, que pode estar auxiliando na manutenção da variabilidade genética.
Overfishing influences changes in the life strategy of populations of aquatic organisms, especially elasmobranchs (sharks and rays). The knowledge and identification of stocks of populations represent a fundamental point for the management and conservation of the species. The species Squalus acanthias is a small shark, belonging to the genus Squalus, popularly known as the spiny dogfish, widely distributed, migratory and susceptible to overfishing. In Argentina, there is a high occurrence of fishing on S. acanthias, which is currently classified as Vulnerable (VU) on the IUCN (International Union for Conservation of Nature) red list. In this context, the present work aims to study samples of S. acanthias, trying to track SNP markers for population and kinship studies, study the genetic composition of a population and study the occurrence of multiple paternity. The ddRADSeq library was performed with females and six litters, ranging from three to 12 pups/mother, totaling 40 samples from Mar del Plata (n=17) and Puerto de Santa Cruz (n=23), Argentina. After sequencing, marker screening was performed, resulting in 4.157 SNPs. The genetic diversity indices were moderate (for observed heterozygosity and expected heterozygosity), in addition, the inbreeding coefficient (FIS) was negative for both analyzed localities, indicating an excess of heterozygotes and absence of inbreeding. The pairwise FST was 0.042 between the regions of Mar del Plata and Puerto de Santa Cruz, demonstrating the absence of population structure. The analyzes with the STRUCTURE and DAPC programs indicated that the analyzed individuals are distributed in three genetic clusters, in addition, a high gene flow was found between individuals from different locations, with a low effective population size (Ne). Kinship analyzes revealed genetically well-related individuals. In the COLONY program, 35 full-sibling relationships were identified, distributed in eight groups that varied in size from two to five individuals, and 45 half-sibling relationships, and multiple paternity was detected in three of the six litters analyzed. This is the first study that evaluated the genetic diversity, population structure and multiple paternity in the S. acanthias species off the coast of Argentina with SNPs markers. The results obtained show evidence of the occurrence of a single panmitic unit on the coast of Argentina and the occurrence of multiple paternity in the species, which may be helping to maintain the genetic variability.
Overfishing influences changes in the life strategy of populations of aquatic organisms, especially elasmobranchs (sharks and rays). The knowledge and identification of stocks of populations represent a fundamental point for the management and conservation of the species. The species Squalus acanthias is a small shark, belonging to the genus Squalus, popularly known as the spiny dogfish, widely distributed, migratory and susceptible to overfishing. In Argentina, there is a high occurrence of fishing on S. acanthias, which is currently classified as Vulnerable (VU) on the IUCN (International Union for Conservation of Nature) red list. In this context, the present work aims to study samples of S. acanthias, trying to track SNP markers for population and kinship studies, study the genetic composition of a population and study the occurrence of multiple paternity. The ddRADSeq library was performed with females and six litters, ranging from three to 12 pups/mother, totaling 40 samples from Mar del Plata (n=17) and Puerto de Santa Cruz (n=23), Argentina. After sequencing, marker screening was performed, resulting in 4.157 SNPs. The genetic diversity indices were moderate (for observed heterozygosity and expected heterozygosity), in addition, the inbreeding coefficient (FIS) was negative for both analyzed localities, indicating an excess of heterozygotes and absence of inbreeding. The pairwise FST was 0.042 between the regions of Mar del Plata and Puerto de Santa Cruz, demonstrating the absence of population structure. The analyzes with the STRUCTURE and DAPC programs indicated that the analyzed individuals are distributed in three genetic clusters, in addition, a high gene flow was found between individuals from different locations, with a low effective population size (Ne). Kinship analyzes revealed genetically well-related individuals. In the COLONY program, 35 full-sibling relationships were identified, distributed in eight groups that varied in size from two to five individuals, and 45 half-sibling relationships, and multiple paternity was detected in three of the six litters analyzed. This is the first study that evaluated the genetic diversity, population structure and multiple paternity in the S. acanthias species off the coast of Argentina with SNPs markers. The results obtained show evidence of the occurrence of a single panmitic unit on the coast of Argentina and the occurrence of multiple paternity in the species, which may be helping to maintain the genetic variability.
Descrição
Palavras-chave
Conservação, Tubarão, Genômica, Diversidade genética, Polimorfismo de nucleotídeo único