Genomics signature in stingrays freshwater species P. motoro and P. falkneri (Chondrichthyes, Potamotrygonidae) in the process of occupation the Paraná River Basin using the second generation sequencing (NGS)

Abstract

Among the Elasmobranchs, the stingrays of the family Potamotrygonidae an important part of the Neotropical ichthyofauna, is the only group of elasmobranchs totally restricted to the freshwater environment. This family comprises 26 valid species, which are distributed in the genera Heliotrygon, Paratrygon, Plesiotrygon and Potamotrygon. Paraná River Basin, in the late 70s, the occurrence of stingrays were noted only below of downstream of the Sete-Quedas Waterfalls, a major geographical barrier located in the Municipality of Guaira, State of Parana. With the construction of the Itaipu hydroelectric near the city of Guaira - PR, there was flooding in the region of the Sete-Quedas Waterfalls, enabling the expansion of the area of occurrence of different species of fish that were limited to the low and middle Paraná river promoting a drastic change in fish populations in the basin of the Upper Parana. Among these species, the stingrays Potamotrygon motoro and P. falkneri are presenting a large population growth in these areas recently occupied. In this regard, we consider the possibility of creating a new dynamic in the population structure of these species, which would result in a profound change in the evolutionary potential of these species. Thus, it becomes extremely important to characterize current genetic variability of evolutionary significant units and their geographical distribution, characterization of gene flow, historical events of population expansions and family structures. Considering the ecological issues related to the potential applicability of genetic information and the still incipient knowledge about these species, this study will seek to provide information on the history and current genetic status of these populations using molecular markers in the species P. motoro and P. falkneri existing in different regions of the Paraná River basin. For the various analyzes will be developed and applied markers, single nucleotide polymorphism (single nucleotide polymorphism - SNP), SNPs from second-generation sequencing (NGS), and microsatellite markers developed for the species P. motoro and present great transferability to P. falkneri. Search will identify possible genomic differences associated with new environments occupied, with the use of second-generation genetic markers. It is considered that the results may lead to information relevant to a better understanding of the mechanisms involved in the diversification of the family Potamotrygonidae, to characterize the genetic variability in baseline populations found in the lower basin of the Paraná river and the genotypes found in representatives established in the upper Paraná river. The use of such markers will enable the characterization of the current situation of the genetic structure of populations of these species and provide information about the process of establishment of new genotypes in specific environments occurrence.