Genetic diversity and population structure of Brycon nattereri (Characiformes: Bryconidae): a Neotropical fish under threat of extinction

Abstract

Brycon nattereri is an endangered Neotropical fish reported along conserved stretches of the upper Paraná, Tocantins and São Francisco rivers. Populations of this species have been very rare in some Paraná River sub basins. This study analyzes the genetic diversity and population structure of B. nattereri in a restricted area of occurrence recently identified in upper Paraná River basin. Seven microsatellite loci and 497 bp of D-Loop mitochondrial region were examined in 92 individuals from four points along the area of occurrence. Both molecular markers indicated a single population distributed along a stretch of the river approximately 80 km long. Although some of the data suggest an ancient bottleneck, current levels of genetic diversity (H E = 0.574 and h = 0.616) were similar to those of other species of the genus Brycon. The results suggest that the population of B. nattereri has been able to maintain satisfactory levels of genetic diversity, in spite of the small area of occurrence. These data have highlighted an important conservation area and action may prove essential to improve the quality of the environment, and especially the water and riparian plant life, if the area is to be managed and conserved efficiently.

Inventory of the fish fauna from Laranjinha River, Paranapanema River system, Brazil

“…The fact that some of these fish appear on a list of endangered species is concerning and it reinforces that the focused area needs appropriate conservation strategies (Simic et al 2007). Studies on B. nattereri reinforce the importance of Laranjinha River conservation, since this migratory and threatened species has been able to maintain a satisfactory population genetic diversity due to the quality of that environment (Galindo et al 2019).…”

“…Frota et al 2016, Froehlich et al 2017, Cavalli et al 2018, Ota et al 2018, Jarduli et al 2020. The Paranapanema River, a major tributary of the upper Paraná River, is currently fragmented by several hydroelectric dams (Britto & Carvalho 2006), and therefore, its dam-free tributaries are of great importance for the maintenance of fish species (Hoffmann et al 2005, Silva et al 2017, Galindo et al 2019, Lansac-Tôha et al 2019. Besides, the Cinzas River is an important tributary of the Paranapanema River basin, which is the main watercourse of the region known as "Norte Pioneiro" (Pioneer North) of the Paraná state, and it is essential for maintaining ichthyofauna biodiversity of the Capivara reservoir (Vianna & Nogueira 2008, Orsi 2010.…”

“…However, a comprehensive checklist of the Laranjinha River ichthyofauna has not been published yet, except for a small streams (e.g., Costa et al 2013), and the scientific knowledge of its fish species remains unknown. Furthermore, projects of Small Hydropower Plants (SHPs) are being developed, which represents a potential threat to the species of this river (Galindo et al 2019). Thus, this study aimed to provide the first inventory of the Laranjinha River fish fauna.…”