Evidence of lack of population substructuring in the Brazilian freshwater fish Prochilodus costatus

Abstract

Curimbatá-pióa (Prochilodus costatus Valenciennes, 1850) is an endemic species from the São Francisco River Basin with migratory habits, important ecological role in the ecosystem and relevant fishing importance. The present study aimed to assess the genetic variation in P. costatus in order to investigate its population genetic structure. Genetic variation was studied at three sites downstream the Três Marias dam (Upper-middle São Francisco River, State of Minas Gerais) through six specific microsatellite loci. Fish from the three sites had quite similar genetic diversity levels and no genetic differentiation was detected, suggesting that P. costatus might represent a single reproductive unit in the studied area. Alternatively, the present study was not able to detect putative coexistent and comigrating populations along the main channel river. Our findings could be very helpful for the management and conservation of this fish.

The roles of marginal lagoons in the maintenance of genetic diversity in the Brazilian migratory fishes Prochilodus argenteus and P. costatus

“…The occurrence of null alleles and stuttering seems to be the most probable cause of these deviations because all of the deviations were associated with the occurrence of null alleles. Additionally, F IS values in P. costatus were positive in 80% of the estimates, also observed previously in the same species (Carvalho-Costa et al, 2008).…”

“…The migration behavior, which is common in prochilodontids (Castro & Vari, 2004) likely plays an important role in the continuous gene flow in these species, keeping them as a single unit in the studied area. Variability levels in microsatellites with a mean number of 9.6 alleles per locus in Prochilodus argenteus and 12.9 alleles per locus in P. costatus were similar to those reported in freshwater fish with an average of 9.1 alleles per locus (DeWoody & Avise, 2000) and were similar to or higher than previous studies with both Prochilodus species (Hatanaka et al, 2006;Carvalho-Costa et al, 2008;Sanches et al, 2012). High genetic diversity was previously identified in P. lineatus (Sivasundar et al, 2001), which can be explained by the capacity of Prochilodus species to perform great migrations and by their large occurrence along the rivers.…”

“…The population differentiation indexes F ST and R ST , the chord genetic distance associated to a high gene flow and previous studies (Carvalho-Costa et al, 2008;Sanches et al, 2012) corroborate the panmictic unit model for both species. The migration behavior, which is common in prochilodontids (Castro & Vari, 2004) likely plays an important role in the continuous gene flow in these species, keeping them as a single unit in the studied area.…”

“…The R ST values under the SMM are expected to be greater than the F ST values under the IAM (Slatkin, 1995), although the inverse has been observed in some fish species (e.g., Pereira et al, 2009). Low indexes of F ST have been observed in other studies with characiforms, such as in Colossoma macropomum (Santos et al, 2007), Piaractus mesopotamicus (Calcagnotto & DeSalle, 2009;Iervolino et al, 2010), Prochilodus argenteus (Hatanaka et al, 2006;Sanches et al, 2012), Prochilodus costatus (Carvalho-Costa et al, 2008), Prochilodus lineatus (Revaldaves et al, 1997) and Salminus brasiliensis (Lopes et al, 2007).…”

“…Population genetic studies have been performed with both Prochilodus species from the rio São Francisco basin using Random Amplified Polymorphic DNA (RAPD) technique (Hatanaka & Galetti, 2003) and microsatellites (Hatanaka et al, 2006;Carvalho-Costa et al 2008;Sanches et al, 2012;Barroca et al, 2012). However, there is no knowledge about the main nursery areas of the populations of either species or the importance of the marginal lagoons in the maintenance of the genetic variability of these or other migratory species.…”