Metapopulation dynamics of the migratory fish Prochilodus lineatus (Characiformes: Prochilodontidae) in a lotic remnant of the Grande River, Southeastern Brazil

River impoundments for electricity generation lead to environmental changes which severely affect fish migration and species richness. However, little is known about their effect on the genetic structure and population dynamics downstream from the reservoir. Here, we analyzed a set of ten microsatellite loci of Prochilodus lineatus, an important South American migratory fish. Specimens (n = 150) were sampled from five sites in a remnant lotic system that includes sections of the Grande, Pardo and Mogi Guacu rivers, southeastern Brazil. The data showed that all microsatellites were polymorphic with the allele number per locus ranging from 5 to 32, and genetic diversity (He) varied from 0.74 to 0.80. Indices of genetic differentiation and Bayesian analysis showed a significant genetic structure and three genetic clusters inhabiting this river system. An asymmetric gene flow suggests source-sink metapopulation dynamics from tributaries (genetic source) to the main river (genetic sink). A genetic cluster that was not detected in the upper Mogi and Pardo rivers tributaries may indicate there is a trapped gene pool downstream from the Porto Colombia dam. Thus, here we provide new insights into the genetic structure and population dynamics of a migratory fish species in a highly dammed river basin.

Automated summary

This study analyzed the genetic structure and population dynamics of Prochilodus lineatus in a remnant lotic system in southeastern Brazil. Significant genetic structure and three genetic clusters were identified in this river system, with asymmetric gene flow indicating source-sink metapopulation dynamics. The presence of a genetic cluster downstream from the Porto Colombia dam suggests a trapped gene pool in this highly dammed river basin.