Temporal-scale assessment of population genetics of the freshwater fish Prochilodus magdalenae in an area impacted by construction of a dam

Abstract

Habitat fragmentation is among the main threats to freshwater fish biodiversity, with expected effects including genetic impacts due to disturbance of migration and declining population size. Major concern falls on highly exploited species such as Prochilodus magdalenae, a migratory characiform fish endemic to the Magdalena River basin supporting much of the Colombian artisanal fishery, whose migration route was interrupted by the Ituango hydroelectric project in the Cauca River. To determine the potential effects of fragmentation, this study evaluated the population genetics of this species on both geographical (upstream and downstream of the dam) and temporal (before and after the construction) scales by using 11 species-specific microsatellite markers. Contrary to expectation, genetic diversity and structure remained relatively stable. This study provided no evidence of genetic impacts on P. magdalenae associated with fragmentation over the short term (4–10 years, 5–12 generations) despite persisting threats, genetic evidence of bottleneck, and a high degree of inbreeding, showing the ability of this species to withstand disturbance of its habitat.