Abstract
The rio São Francisco basin contains many endemic species, such as Prochilodus argenteus and P. costatus, which have great commercial importance. However, information about the main recruitment sites and genetic studies containing extensive sampling of these species are scarce. To investigate the roles of the marginal lagoons in the maintenance of genetic variability and in the population structure, we analyzed six microsatellite loci in nine sampling groups of P. argenteusand five sampling groups of P. costatus. Our results showed high levels of genetic variability and low values of genetic differentiation for P. argenteus (FST =0.008, P< 0.05) and for P. costatus(FST =0.031, P < 0.05). In addition, high values of gene flow combined with a small genetic distance suggest the presence of a single population for each species in the middle rio São Francisco basin. Moreover, putative migration routes involving marginal lagoons during the reproductive season could be detected, confirming the importance of these nurseries in the lifecycle of these species. Our results also indicate the necessity of adequate management of the fish resources and the conservation of the floodplains in the rio São Francisco basin.
Highlights
The rio São Francisco basin constitutes an area that covers 619,543 km2, ca. 7.5% of Brazil, with ecological domains ranging from Atlantic rainforest to Cerrado and Caatinga
Sampling sites Migratory fishes reproduce in the mainstream or tributaries of the rio São Francisco basin, and their eggs and larvae are carried out downstream reaching marginal lagoons (Moojen, 1940) that stay unconnected of the mainstream in the dry season
Six out of 54 HWE tests performed for P. argenteus (6 microsatellite loci in 9 sampling groups) were significant
Summary
The rio São Francisco basin constitutes an area that covers 619,543 km, ca. 7.5% of Brazil, with ecological domains ranging from Atlantic rainforest to Cerrado and Caatinga. Prochilodus argenteus, an endemic species from the rio São Francisco basin, nowadays introduced in other Neotropical drainages (Castro & Vari, 2004), is the largest member of the Prochilodontidae family and is among the most important recreational and commercial fish species in the basin (Camargo & Petrere, 2001; Godinho et al, 2003) Another endemic species, P. costatus, has an importance in the subsistence fishery, as one of the most captured species in that region (Camargo & Petrere, 2001)
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