The human activities impact on wild animal populations is indicated by eco-evolutionary and demographic processes, along with their survival and capacity to evolve; consequently, such data i can contribute towards enhancing genetic-based conservation programs. In this context, knowledge on t the life-history and the eco-evolutionary processes is required to understand extant patterns of r to population loss and structure fragmentation in Prochilodus of its costatus natural a habitat Neotropical since migratory 1960s promoted fish that has by been the threatened expansion due of A hydroelectric integrated parameters approach that power cause was plant oscillations used, construction including in the temporal demography programs. and spatial This and structure sampling, study evaluated of next-generation P. costatus the eco-evolutionary populations. sequencing An of eight microsatellite loci, multivariate genetic analysis, and demographic life-history reconstruction. d The interference results events provided on the evidence life-history of the of this complex species interplay in the upper of ecological-evolutionary basin. In particular, spawning and human- waves behavior might have ecological triggers resulting in an overlapping of distinct genetic generations, e and arising distinct migratory and non-migratory genetic patterns living in the same area. An abrupt decrease in the effective population size of the P. costatus populations in the recent past (1960–80) t was likely driven by environment fragmentation promoted by the construction of the Três Marias p active hydropower stocking dam. programs The low are allelic not diversity effective that at expanding resulted from the genetic this event diversity is still of detected this species today; in thus, the e river and temporal basin. Finally, variation this in study genetic highlights structure the importance for effective of mitigation using mixed and methods conservation to understand programs spatial for c threatened species that are directly affected by human actions.