Genetic composition of stingrays of the genus Pseudobatos (Chondrichthyes, Rhinobatidae) and search for SNPs associated with environmental adaptation

Abstract

The aquatic species are among those who most suffer from the rapid environmental changes, promoting, thus, threats to biodiversity, as well as the decrease in the species fitness potential to adapt to future environments. As a result of the genomic revolution, the development of various next-generation sequencing methods (Next Generation Sequencing-NGS) transformed the field of functional genomics in the last five years, allowing us to identify single nucleotide polymorphisms (SNPs) across the genome atrelatively modest costs. This methodology can be applied to any species in which it is possible to trace loci under selection, thereby identifying loci outliers related to genetic basis of the features involved in environmental adaptability of organisms. An interesting model for such evolutionary studies is represented by the species of elasmobranchs group, more precisely the rays. They occupy aquatic environments with different characteristics. Pseudobatos horkelii and P. percellens species are coastal rays popularly known in Brazil as guitarfish, belonging to the family Rhinobatidae. P. horkelii occurs from Rio de Janeiro to the North of Argentina, while P. percelens have its distribution from the Gulf of Mexico to northern Argentina. Among the few studies developed with these species, the reproductive biology, population dynamics, food habits and distribution stand out. Although the species from the Rhinobatidae family do not constitute the main target of industrial and artisanal fishing, they are captured as bycatch, which currently ranks P. horkelli as "critically endangered" in the Red List (International Union for Conservation of Nature), while P. percellens is classified as "near threatened". On the above, it can be highlighted the importance of track markers linked to environmental adaptation and the species of rays P. horkelii and P. percellens will be reviewed from samples obtained from localities in the Gulf of Mexico (USA), Northern Venezuela, coast of Maranhão, Rio Grande do Norte, Paraíba, Pernambuco, Bahia, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul states (Brazil), and in the region of Mar del Plata (Argentina), with a total of 13 locations, seeking to identify possible relationships between populations using SNPs. In addition to establishing phylogeographical relations between the different populations/species identified by checking if the stocks of the Northeast and Southeast are isolated and determine the existence of genetic population structure, the effects selective environment-related pressure on the species will be investigated. (AU)