Estruturação e dinâmica populacional de pellona castelnaeana, valenciennes, 1847, e evidências de unidades evolutivas em pellona flavipinnis (valenciennes, 1837) na bacia amazônica

Abstract

The Amazon basin has one of the largest and most complex ecosystems in the world, and harbors the highest diversity of freshwater fishes. Within this ichthyofauna, the fishes of the genus Pellona, commonly known as the “Amazon pellona”, are among the few clupeiform species with a recognized economic value. The genus has two representatives in the Amazon basin: P. castelnaeana Valenciennes, 1847 and P. flavipinnis (Valenciennes,1837). The aims of this study were: (i) to characterize microsatellite loci of Pellona castelnaeana, and their transferability to P. flavipinnis; (ii) to evaluate the genetic variability and population structure in P. castelnaeana and (iii) to understand the distribution of the genetic diversity in P. flavipinnis. To reach aim (i), we isolated and characterized 8 microsatellite loci. The characterization was realized with 9 to 19 individuals of P. castelnaeana from Santarém, and 27 to 31 individuals of P. flavipinnis from Manaus. To achieve aim (ii), we sequenced 175 individuals for the the mitochondrial DNA control region and genotyped 119 individuals for 7 microsatellite loci. Individuals were sampled from five localities in the mainstream of the Amazon River, six tributaries of the Amazon river and one locality in the Guapore river (Bolivian subbasin). The control region results for P. castelnaeana showed lack for population structuring within the Amazon basin, but a signal of substructure when compared with the Bolivian subbasin (Fst=0.3172). The diversity index was high, with mean gene and nucleotide diversity of (Ĥ=0.8646) and (π=0.044236), respectively. Analyses of the microsatellite data in the program Structure showed a population structure, indicating that the sampling area in this study could be divided in four macro regions: three in the Amazon basin and one in the Bolivian subbasin. The expected (HE) and observed (HO) heterozygozity value ranged among 0.42211 to 0.79681 and 0.23564 to 0.63561, respectively. Markers in both single and two parent results indicated that the rapids and waterfalls of the upper Rio Madeira acted restringuindo gene flow between the Amazon basin and sub-basin Boliviana. To achieve aim (iii), the COI gene was sequenced in 99 individuals, the control region was sequenced in 114 individuals and 7 microsatellite loci were genotyped in 73 individuals of P. flavipinnis. Pellona flavipinnis was collected in four localities in the mainstream of the Amazon basin, in two localities downstream and upstream of the Madeira river rapids and in five other tributaries of the Amazon river. The results suggested the existence of two co-occurring groups (lineages A and B) in the localities of Tabatinga, lower Madeira river and Santarem. The genetic distance obtained from the COI sequences between these two lineages was 2.3%, and lineage B showed larger diversity. The presence of two lineages was confirmed by the analysis with the microsatellite loci, that also suggest the existence of two biological groups in this species. A BAPS analysis of control region sequences showed the existence of three biological groups of P. flavipinnis, one confirming the A lineage and two within the B lineage. This study presents new data on the population structure of the Amazon pellona in the Amazon basin, and can contribute to management and conservation planning.