Genetic diversity of Arapaima gigas (Schinz, 1822) (Osteoglossiformes: Arapaimidae) in the Araguaia-Tocantins basin estimated by ISSR marker

Abstract

The genetic diversity of the specimens of four natural populations of Arapaima from Araguaia-Tocantins basin was assessed within and among these stocks, using five primers for ISSR. COI (cytochrome c oxidase subunit I) partial sequences confirmed that the specimens belongs to Arapaima gigas. The ISSR provided 168 loci, of which 165 were polymorphic. However, the number of loci for each population and expected heterozygosity values were low. AMOVA showed 52.63% intra-population variation and 47.37% inter-population variation. The F ST was high among all populations (F ST ≥ 0.25), however, the cluster analysis (PCoA) and Bayesian inference showed three major groups: Araguaiana-MT + São Félix do Araguaia-MT, Novo Santo Antônio-MT and Itupiranga-PA. The genetic distance was not correlated with geographical distance. The ISSR marker revealed that the populations of the Araguaia-Tocantins are structured and have a low genetic diversity. These are the first data from a population analysis using molecular markers for A. gigas of Araguaia-Tocantins basins and may be used to define the best management strategies and conservation projects for this species.A diversidade genética dos espécimes de quatro populações naturais de Arapaima coletados na bacia do Araguaia-Tocantins foi avaliada com base em cinco primers para marcadores moleculares ISSR. A sequência parcial do COI (cytochrome c oxidase subunit I) confirmou que os espécimes pertencem à espécie Arapaima gigas. Os ISSR forneceram 168 loci, dos quais 165 polimórficos. No entanto, para cada população, os valores de heterozigosidade esperada foram baixos. A AMOVA mostrou 52,63% de variação intrapopulacional e 47,37% interpopulacional. O F ST foi alto entre todas as populações (F ST ≥ 0,25); entretanto, a análise de agrupamento e a inferência Bayesiana mostraram três grandes grupos: Araguaiana-MT + São Félix do Araguaia-MT, Novo Santo Antônio-MT e Itupiranga-PA. A distância genética não teve correlação com a distância geográfica. Os ISSRs se mostraram eficientes para determinar a diversidade genética para a A. gigas, revelando que as populações da bacia Araguaia-Tocantins estão estruturadas e com baixa diversidade genética. Estes são os primeiros dados de análise populacional utilizando ISSR para A. gigas da bacia Araguaia-Tocantins e poderão ser utilizados para definir as melhores estratégias de manejo e projetos de conservação dessa espécie.

Genetic diversity and structuring in the arapaima (Osteoglossiformes, Osteoglossidae) population reveal differences between the Amazon and the Tocantins-Araguaia basins

“…The structuring observed in the Tocantins-Araguaia basin, which has only a single lineage, and the high Fst values recorded in the extremes of this basin are consistent with previous studies in this region, which indicate low levels of gene flow and structuring in the resident populations (Vitorino et al 2015(Vitorino et al , 2017. Historical population bottlenecks, followed by genetic drift may have further reinforced this structuring.…”

“…The hypothesis that the genetic divergence between arapaimas is derived primarily from the geographic isolation of populations has been refuted progressively (Araripe et al 2013, Fazzi-Gomes et al 2017a, Vitorino et al 2017. The factors most frequently associated with this structuring are historical reductions in stocks (Araripe et al 2013, Vitorino et al 2015, the sedentary behavior of the species (Araripe et al 2013, Vitorino et al 2015, Fazzi-Gomes et al 2017a, the impact of fisheries on stocks (Hrbek et al 2005, Vitorino et al 2015, and the characteristics of each basin and its floodplain dynamics (Vitorino et al 2015, Watson et al 2016. It does seem likely that these processes may have influenced the structuring of the arapaima populations over time, molding their connectivity and restricting gene flow between the different hydrographic basins.…”

“…Population and phylogeographic studies of the arapaima have identifi ed different levels of structuring in the populations within the Amazon and Tocantins-Araguaia basins, although the samples analyzed in these studies were not adequate for conclusive comparisons of the genetic structure of the two basins (Hrbek et al 2005. This comparison is hampered by the small sample size, especially from the Tocantins-Araguaia basin (Hrbek et al 2005, or the restriction of the samples to only one basin (Vitorino et al 2015, Fazzi-Gomes et al 2017a. While the arapaima is classified as a sedentary fish (Castello 2008), phylogeographic studies based on mitochondrial DNA markers have demonstrated high levels of gene flow, indicating that they form a continuous population (Hrbek et al 2005).…”

“…Genetic studies in different areas of the Amazon region have provided important insights into the variation among populations within the geographic range of the species, which is fundamental to the management of this fishery resource (Escobar et al 2015, Fazzi-Gomes et al 2017b. The genetic differentiation of arapaima populations observed at some points in the distribution of the species (Vitorino et al 2015, Watson et al 2016, Fazzi-Gomes et al 2017a may be related to the distinct characteristics of the floodplains and drainage systems of each basin, which may have a direct influence on the migration patterns of the species (Castello 2008). The Amazon basin is a complex system composed of large tracts of tropical forest interspersed with rivers, lakes and channels (Ayres 2006).…”

Historical demography and climate driven distributional changes in a widespread Neotropical freshwater species with high economic importance

“…Previous studies on the population genetic diversity of A. gigas with molecular markers generally pointed to the absence of genetic structuring in the Am and lower To‐Ar basins, and a more pronounced structuring in the upper To‐Ar. These previous analyses, however, focused on few mtDNA sequences (Hrbek et al ), nuclear markers associated with repetitive regions (Hrbek et al , Vitorino et al , , Farias et al ), and randomly distributed genotypes along the genome (Torati et al ). Here, we sampled specimens in the field and deposited vouchers for both wild populations and fish farms, obtaining SNP markers with DArTSeq (Kilian et al ).…”