Seascape genomics and phylogeography of the sailfish (Istiophorus platypterus)

Permeable phylogeographic barriers characterize the vast open ocean, boosting gene flow and counteracting population differentiation and speciation of widely distributed and migratory species. However, many widely distributed species consists of distinct populations throughout their distribution, evidencing that our understanding of how the marine environment triggers population and species divergence are insufficient. The sailfish is a circumtropical and highly migratory billfish that inhabits warm and productive areas. Despite its ecological and socioeconomic importance as a predator and fishery resource, the species is threatened by overfishing, requiring innovative approaches to improve their management and conservation status. Thus, we presented a novel high-quality reference genome for the species and applied a seascape genomics approach to understand how marine environmental features may promote local adaptation and how it affects gene flow between populations. We delimit two populations between the Atlantic and Indo-Western Pacific oceans and detect outlier loci correlated with sea surface temperature, salinity, oxygen, and chlorophyll concentrations. However, the most significant explanatory factor that explains the differences between populations was isolation by distance. Despite recent population drops, the sailfish populations are not inbred. For billfishes in general, genome-wide heterozygosity was found to be relatively low compared to other marine fishes, evidencing the need to counteract overfishing effects. In addition, in a climate change scenario, management agencies must implement state-of-the-art sequencing methods, consider our findings in their management plans, and monitor genome-wide heterozygosity over time to improve sustainable fisheries and the long-term viability of its populations.LA/P/0101/2020info:eu-repo/semantics/publishedVersio

High connectivity of the Crocodile Shark between the Atlantic and Southwest Indian Oceans: highlights for conservation

Among the various shark species that are captured as bycatch in commercial fishing operations, the group of pelagic sharks is still one of the least studied and known. Within those, the crocodile shark, Pseudocarcharias kamoharai, a small-sized lamnid shark, is occasionally caught by longline vessels in certain regions of the tropical oceans worldwide. However, the population dynamics of this species, as well as the impact of fishing mortality on its stocks, are still unknown, with the crocodile shark currently one of the least studied of all pelagic sharks. Given this, the present study aimed to assess the population structure of P. kamoharai in several regions of the Atlantic and Indian Oceans using genetic molecular markers. The nucleotide composition of the mitochondrial DNA control region of 255 individuals was analyzed, and 31 haplotypes were found, with an estimated diversity Hd = 0.627, and a nucleotide diversity pi = 0.00167. An analysis of molecular variance (AMOVA) revealed a fixation index phi(ST) = -0.01118, representing an absence of population structure among the sampled regions of the Atlantic Ocean, and between the Atlantic and Indian Oceans. These results show a high degree of gene flow between the studied areas, with a single genetic stock and reduced population variability. In panmictic populations, conservation efforts can be concentrated in more restricted areas, being these representative of the total biodiversity of the species. When necessary, this strategy could be applied to the genetic maintenance of P. kamoharai.Foundation for Research Support of the Sao Paulo State - FAPESP [2011/23787-0, 2010/51903-2]; Portuguese Foundation for Science and Technology (FCT) [SFRH/BPD/93936/2013]; Foundation for Research Support of the Sao Paulo State - FAPESP [2011/23787-0, 2010/51903-2]; Portuguese Foundation for Science and Technology (FCT) [SFRH/BPD/93936/2013]info:eu-repo/semantics/publishedVersio

Caracterização da estrutura genética populacional do tubarão-crocodilo (Pseudocarcharias kamoharai) no Atlântico equatorial utilizando marcadores moleculares

Para o setor pesqueiro, a identificação e manutenção de estoques diferenciados são fundamentais, pela sua relação direta com a produtividade total e uso sustentável dos recursos, sendo um dos objetivos básicos para programas de controle e conservação de espécies em perigo, a conservação da variabilidade genética. Entre os tubarões mais explorados, as espécies pelágicas apresentam uma maior complexidade na avaliação e monitoramento de suas populações devido às suas distribuições em vastas áreas geográficas. Entre essas espécies, Pseudocarcharias kamoharai, popularmente conhecida como tubarão-crocodilo ou tubarão-cachorro, atinge tamanhos máximos em torno de 140 cm de comprimento total, habita profundidades máximas em torno de 600 metros e ocorre em todos os oceanos tropicais, sendo registrada no Brasil principalmente nas áreas oceânicas do Nordeste. A análise genética molecular realizada utilizando sequências da região controladora do DNA mitocondrial (D-loop) de 125 indivíduos capturados em quatro regiões distintas no Oceano Atlântico (Equatorial Oeste, Noroeste Africano, Golfo da Guiné e Sudoeste Africano) Permitiu identificar 22 haplótipos com diversidade haplotípica h=0.627 e diversidade nucleotídica π=0.00167. Estes índices são similares aos encontrados em outras espécies de tubarões pelágicos também do Atlântico e podem ser considerados dentro dos níveis médios de diversidade genética entre os tubarões. O índice de FST=0.00125 obtido nas comparações pode sugerir ausência de estruturação populacional entre os quatro grupos amostrados. Tendo em vista a contínua inclusão de espécies de tubarões na Lista Vermelha da União Internacional para a Conservação da Natureza e dos Recursos Naturais (IUCN), os resultados obtidos neste estudo podem auxiliar na gestão adequada da pesca e na conservação desta espécie no Oceano AtlânticoFor the fishing sector, the identification and delimitation of the fishing stocks constitute fundamental information due to their direct relationship to the overall productivity and sustainable utilization of the resources. This constitutes a basic objective in terms of population management and conservation of endangered species that can be represented by the conservation of the genetic variability. Among the most exploited sharks, pelagic species have a greater complexity in terms of evaluation and monitoring due to their distributions along large geographical areas. One of these species is the crocodile shark, Pseudocarcharias kamoharai, which reaches maximum sizes of around 140 cm in total length, inhabits maximum depths of around 600 meters, and occurs in all tropical oceans including in Brazil, mainly in the Northeast region. The molecular genetic analysis using sequences of the mitochondrial DNA control region (D-loop) of 125 individuals captured in four distinct regions in the Atlantic Ocean (Western Equatorial, Northwest Africa, Gulf of Guinea and Southwest Africa), allowed the identification of 22 haplotypes which revealed a haplotype diversity of h=0627 and a nucleotide diversity of π=0.00167. These indices showed to be similar to those found in other species of pelagic sharks, also from the Atlantic sites and can be considered inside of the average levels of genetic diversity among the sharks. The value of FST=0.00125 index found in the comparisons may suggest the absence of population subdivision among the four sampled regions analyzed. Given the continued inclusion of shark species in the Red List of the International Union for Conservation of Nature and Natural Resources (IUCN), the results obtained in this study may be used to help a more sustainable management of fisheries and conservation programs of this species in the Atlantic OceanCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Marcadores de Microssatélites para estudos de conservação da Raia-viola Rhinobatos percellens (Chondrichthyes, Rhinobatidae)

A exploração pesqueira, tanto artesanal quanto industrial, se constitui na maior ameaça à biodiversidade dos elasmobrânquios. Em escala mundial, o manejo adequado destes recursos é dificultado pela escassez de informações básicas sobre a dinâmica populacional destes organismos. A captura comercial de elasmobrânquios tem alcançado números alarmantes, com a inclusão de diversas espécies nas listas de risco de extinção nacional e também internacional. A identificação e a conservação de estoques geneticamente diferenciados e adaptados ao seu habitat, representam um ponto fundamental para o setor pesqueiro, pela sua relação direta com a produtividade total e o uso sustentável dos recursos. Entre as raias marinhas, a família Rhinobatidae é representada pelos gêneros Rhinobatos, Zapteryx, Trygonorhina e Aptychotrema, sendo registrada a ocorrência da espécie Rhinobatos percellens no Oceano Atlântico adesde as Antilhas e Panamá, Venezuela, Jamaica, Brasil, Uruguai, até a Argentina. No presente trabalho foram desenvolvidos marcadores moleculares do tipo microssatélites para raiaviola, Rhinobatos percellens, para serem utilizados em estudo populacionais. Cinco locus polimórficos foram isolados utilizando um protocolo de enriquecimento. Nos experimentos, foram testados 13 pares de primers, sendo 10 isolados no presente trabalho e 3 isolados para a espécie de tubarão azul (Prionance glauca). Dos primers isolados em Rhinobatos percellens, 5 são polimórficos, 2 monomórficos e 3 apresentaram bandas muito fracas, enquanto os primers testados de tubarão azul mostraram-se monomórficos. Todos os locus estão em equilíbrio de Wardy-Weinberg, exceto o RVA9 (de R. percellens). Os locus polimórficos apresentam de 3 a 6 alelos por locus e heterozigosidade média esperada de 0.62. Considera-se que estes marcadores polimórficos...(Resumo completo, clicar acesso eletrônico abaixo

Global phylogeography of the smooth hammerhead shark: glacial refugia and historical migration patterns

Extreme climate changes during the Cenozoic Era strengthened different biogeographical barriers that decreased the connectivity among populations, triggering lineage diversification of different species worldwide. The mitochondrial DNA control region was employed to explore the phylogeography of Sphyrna zygaena, a globally distributed species threatened by unsustainable, illegal, unreported and unregulated fisheries triggered by the international shark fin trade. It is listed as 'Vulnerable' by the IUCN Red List and its trade is regulated by CITES Appendix II. Only 13 haplotypes were found with low genetic diversity levels (hd = 0.686 +/- 0.014; pi = 0.00206 +/- 0.00004) compared with other species of the Sphyrnidae family. The species has a very strong phylogeographic population structure among the Atlantic, Indian and Pacific Oceans (phi(ST) = 0.79132). Worldwide, there are six distinct populations with some haplotype sharing. These populations are probably connected by a stepping-stone dispersal of a small number of migrants per generation from the Indo-Pacific towards the Atlantic. Modelling suggests that S. zygaena diverged into two lineages around 6.96 million years ago which have been isolated in glacial refuges in the Atlantic and Indo-Pacific oceans; and after deglaciation, a population expansion probably permitted secondary contact. Conservation plans to establish differentiated management units should be adopted in each of the identified populations. Among these, the Eastern Central Atlantic and West Indo-Pacific are the most important areas for the species considering the historical migration routes that act as a bridge connecting the Atlantic and Indo-Pacific Oceans while the Gulf of Guinea connects the Atlantic populations. Still, further studies are required to know if these populations are also linked with nursery areas for the species. The results herein can help to delimit the main evolutionarily significant units to implement effective policies to establish differentiated management units as starting points to genetic monitoring programmes for Sphyrna zygaena.CNPq 470762/2013-6; BIOTA/FAPESP 2011/23787-0; FRDC 2010/062; FAPESP 2017/17605-3info:eu-repo/semantics/publishedVersio

Global population genetic structure of the sequential hermaphrodite, dusky grouper (Epinephelus marginatus)

The dusky grouper Epinephelus marginatus is a large epinephelid species that occurs in the eastern and south-western Atlantic and western Indian Oceans. Late maturity, protogynous hermaphroditism, site fidelity, and overfishing have all contributed to its demographic decline. Connectivity and demography within a broad sampling of dusky grouper populations throughout its distribution were assessed. To do so, genetic variation at 11 polymorphic microsatellite loci and a partial sequence of the mitochondrial control region (mtCR) were evaluated. Two major mtCR lineages with a sequence divergence of 1.6% were found. The magnitude of genetic differentiation for mtCR among north and south Atlantic and Indian Ocean populations was high, with ΦST = 0.528. DEST and results of discriminant analysis of principal component revealed significant microsatellite genetic differentiation between all collection areas. Significant pairwise DEST showed moderate (0.084) to very great (0.603) differentiation. The effective population size was low for all localities, ranging between 25 (Azores Archipelago) and 311 (Rio Grande do Sul). The overall effective population size was estimated as 299 (confidence interval = 215–412), and there was no evidence of strong or recent bottleneck effects. Local and regional genetic structuring among dusky grouper populations is the consequence of the species' site fidelity, distribution across multiple oceanographic boundaries, and probably also of sequential hermaphroditism that contributes to the intensity of random genetic drift. The spatial pattern of genetic structuring of dusky groupers is such that fisheries management and conservation of population genetic integrity will have to be pursued at the local and regional scales.São Paulo Research Foundation (FAPESP), Grant/Award Numbers: 2015/23.883-0, 2016/20.208-3, 2017/02.420-8; Hatch Program of the National Institute of food and Agriculture, U.S. Departament of Agriculture Experiment Station; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior/Brasil (CAPES).info:eu-repo/semantics/publishedVersio

DNA Barcode Reveals the Bycatch of Endangered Batoids Species in the Southwest Atlantic: Implications for Sustainable Fisheries Management and Conservation Efforts

Today, elasmobranchs are one the most threatened vertebrate groups worldwide. In fact, at least 90% of elasmobranch species are listed in the International Union for Conservation of Nature (IUCN) Red List, while more than 40% are data-deficient. Although these vertebrates are mainly affected by unsustainable fishery activities, bycatch is also one of the major threats to sharks and batoids worldwide, and represents a challenge for both sustainable fishery management and for biodiversity and conservational efforts. Thus, in this study, DNA barcode methodology was used to identify the bycatch composition of batoid species from small-scale industrial fisheries in the southwest Atlantic and artisanal fisheries from southeast Brazil. A total of 228 individuals belonging to four Chondrichthyes orders, seven families, and at least 17 distinct batoid species were sequenced; among these individuals, 131 belonged to species protected in Brazil, 101 to globally threatened species, and some to species with trade restrictions provided by Appendix II of the Convention on International Trade in Endangered Species (CITES). These results highlight the impacts on marine biodiversity of bycatch by small-scale industrial and unmanaged artisanal fisheries from the southwest Atlantic, and support the implementation of DNA-based methodologies for species-specific identification in data-poor fisheries as a powerful tool for improving the quality of fisheries’ catch statistics and for keeping precise bycatch records

Pairwise mismatch distributions for overall sampled regions in the Atlantic and Indian Oceans.

<p>The observed values are represented in the in bars and the expected values in the line.</p

Differentiation (<i>F</i>_ST) between pairs of sampled regions in the Atlantic and Indian Oceans.

<p>Pairwise <i>F</i>_ST below diagonal and p-values above the diagonal.</p><p>Differentiation (<i>F</i>_ST) between pairs of sampled regions in the Atlantic and Indian Oceans.</p