Microsatellite analysis of pacu broodstocks used in the stocking program of Paranapanema River, Brazil

Abstract

Monitoring the genetic diversity has fundamental importance for fish stocking programs. This experiment aims to evaluate the genetic diversity in two hatchery stations (A and B) with pacu Piaractus mesopotamicus (Holmberg, 1887) in Andirá, state of Paraná, Brazil used in stocking programs of Paranapanema River. Six microsatellite loci were amplified using DNA extracted from 60 fin-clipping samples. The broodstock B had the average number of alleles and the mean heterozygosity (alleles: 3.7 and H O : 0.628) higher than the broodstock A (alleles: 3.5 and H O : 0.600). Alleles with low frequency levels were observed in the both broodstocks. Evidence of linkage disequilibrium and lower allelic richness was found only in the broodstock A. Nei's gene diversity was high in both broodstocks. The genetic distance (0.085) and identity (0.918) showed similarity between broodstocks, which reflects a possible common origin. 6.05% of the total genetic variance was due to differences among broodstocks. Recent bottleneck effect in two broodstocks was observed. The results indicated a higher genetic diversity in the two broodstocks and they presented low genetic difference. This was caused by the reproductive management in both hatchery stations, reduction of population size and genetic exchange between the hatchery stations. Key words: Piaractus mesopotamicus, genetic variability, hatchery stations, molecular markers 6,05% da variância genética total foi devida a diferenças entre os estoques. Foi observado um recente efeito gargalo nos dois estoques. Os resultados indicaram uma alta diversidade genética nos estoques de reprodutores e baixa diferenciação genética entre eles, o que foi causado pelo manejo reprodutivo das pisciculturas, redução do tamanho populacional e intercâmbio genético entre as pisciculturas.

Genetic Variability of Brycon hilarii in a Repopulation Program

“…(2015) for broodstock and wild population of Prochilodus lineatus, and by Povh et al (2011) for broodstock and fingerling stocks of Piaractus mesopotamicus, respectively with 11, 44 and 31 alleles. Therefore, the number of alleles in current assay is adequate when compared to that in similar experiments.…”

“…Further, in the case of inadequate management, possible cannibalism by post-larvae B. hilarii during the early phase (usually 36 -96 hours old) may have decreased the effective number of broodstocks and, consequently, genetic variability. A selection of beneficent characteristics for breeding, such as fish selection merely based on external characteristics (male: semen release after encephalic-caudal pressure; female: swelled belly and a reddened urogenital orifice), maturation stage of oocytes (migrated nucleus), regardless of parenthood, variability and genetic divergence, and the effective number of broodstocks (Povh et al 2011) may greatly reduce genetic variability within a single generation and decrease fingerlings´ viability within the natural environment (Christie et al 2012). Povh et al (2008) studied populations of pacu (P. mesopotamicus) for genetic monitoring and registered high rates of genetic variability in fingerlings when compared to broodstocks on the same site.…”

“…Genetic interaction among the fish released and wild populations may cause loss of alleles, especially those related to adaptation ). Molecular markers, especially microsatellites, have been widely used for information on the genetic variability of broodstocks and wild populations (Povh et al 2011;Almeida et al 2013;LoperaBarrero et al 2015). Microsatellites warrant a more specific analysis in population structures since they have high genetic mutation rates when compared to other DNA parts.…”

Genetic diversity of pacu for restocking programs in the Tietê and Grande rivers, Brazil

“…In the Pme4 (IBI1), Pme5 (AGV1), Pme14 (AGV1) and Pme28 (IBI1) loci, there was 100% heterozygosity. Based on studies of WPs of Piaractus (CALCAGNOTTO; DESALLE, 2009;LOPERA-BARRERO et al, 2010a;POVH et al, 2011) the average Ho was high (>45%) from AGV1, NAV1, IBI1, PRO1, BAB1 and in the BSs, which indicated high intrapopulation genetic variability. AGV2, NAV2, IBI2, BAR2 and BAB2 had heterozygosities ranging from 0.203 to 0.394.…”

“…Only a few studies regarding variability and genetic structure using microsatellites markers have been performed in P. mesopotamicus WPs and BSs (CALCAGNOTTO;DESALLE, 2009;LOPERA-BARRERO et al, 2010a;POVH et al, 2010POVH et al, , 2011. The microsatellite marker is the most used technique to achieve this purpose and has Semina: Ciências Agrárias, Londrina, v. 36, n. 6, p. 3807-3826, nov./dez.…”