Knodus moenkhausii (Characiformes: Characidae): one fish species, three hydrographic basins - a natural or anthropogenic phenomenon?

Abstract

We used the DNA barcoding technique (COI and CytB markers) combined with GMYC analysis to characterize the genetics of the widely distributed Neotropical fish species Knodus moenkhausii from three different isolated hydrographic basins. Despite the fact that most of the Neotropical hydrographic basins have been isolated for millions of years, species could be shared between basins due to natural events (stream capture) or anthropogenic activities. Recent surveys, however, have shown that many widely distributed species are actually species complexes divided into previously unrecognized cryptic species. In this study, we tested the hypothesis that K. moenkhausii from three hydrographic basins represent a single panmictic species and discuss the most likely explanation of its present geographical distribution. The GMYC analysis revealed that all specimens of K. moenkhausii represent a single species: the intra- and intergroup minimum K2P genetic distances for both genes were zero and haplotypes were shared among the three hydrographic basins. This suggests there has been recent interchange of K. moenkhausii throughout the three hydrographic basins. It is likely that this is due to recent human activities, either the transposition of natural barriers or intentional introduction or accidental escape due to the ornamental fish trade.

Ichthyofauna of streams of the Rio Sapucaí basin, upper Rio Paraná system, Minas Gerais, Brazil

“…Individuals of two non-native species, Knodus moenkhausii and Poecilia vivipara, were collected in this survey (see Table 3). Knodus moenkhausii (Figure 5d) has previously been assigned by different authors as non-native to the upper Rio Paraná system (e.g., Langeani et al 2007, Souza et al 2015, Azevedo-Santos et al 2018b. Poecilia vivipara (Figure 5g) has also been reported by Langeani et al (2007) as a non-native species introduced to the upper Rio Paraná system.…”

The ichthyofauna of a poorly known area in the middle-southern Espinhaço mountain range, state of Minas Gerais, Brazil: diagnostics and identification keys

“…However, it may be an exotic species which was introduced on the basin in the past (Vieira et al 2015), but future research will be needed to confirm how the species reached the basin. Souza et al (2015) revealed through DNA barcoding technique that K. moenkhausii has been shared throughout rio São Francisco, rio Paraíba do Sul and upper rio Paraná basins, through recent interchange. According to the authors, the species represent a single panmitic species, and its sharing in those basins may have occurred due to different human activity processes, such as intentional introduction, transposition of natural barriers or accidental escape in ornamental fish trade.…”