Filogeografia de Scoloplax baskini Rocha, Oliveira, Rapp py-Daniel, 2008 (Siluriformes, Loricarioidea, Scoloplacidae)

Abstract

Scoloplax baskini belonging to the family Scoloplacidae, endemic to the Neotropical region and comprises only one genus, Scoloplax with six valid species. Family representatives are known to be considered miniature fish because of their diminutive standard length, and the largest known specimen measures 1.99 centimeters in standard length. The representatives of this family have as main characteristic a plaque with small odontoids in the upper region of the muzzle and a bilateral series of bony plaques in the dorsal line between the dorsal and caudal fins. Scoloplax species are widely distributed throughout the Neotropical region, occurring in the Amazon and Paraná-Paraguay basins. In the Amazon basin occurs the greatest diversity, 6 known species. In particular in the Negro river, 4 of the 6 Amazonian species occur. Some populations of Scoloplax, based on a morphological variation, need a detailed analysis. Therefore, the objective of this work was to evaluate the genetic variability of three isolated populations (Black, Purus and Aripuanã) of Scoloplax baskini and its relation with the geographic distribution. In order to do this, we verified the existence of gene flow among populations, estimating the time of divergence among populations, as well as inferring about the demographic and evolutionary processes that contributed to the current population distribution. Two molecular macaders, the subunit of ribosomal RNA (16S) and the subunit I of cytochrome oxidase (DNA barcode), were used for the sampling, amplification, purification and sequencing were done and from these the analysis of molecular variance (AMOVA ), a phylogenetic tree was generated, as well as the genetic distance for the two fragments. The species Scoloplax baskini, presented a wide genetic variability, without genetic flow, besides being verified the time of divergence of these populations, which can be inferred possible marine invasions and retention of brackish water in great part of the central plain of the Amazon, as a potential reason of differentiation of these populations, acting with a process of vicariance in the populations of Scoloplax baskini.