A MICROSATELLITE MARKER TOOL FOR PARENTAGE ANALYSIS IN THE NEO-TROPICAL FRESHWATER FISH PACÚ (Piaractus mesopotamicus, Holmberg, 1891)

VILLANOVA, G.V.; POSNER V.; SANCHEZ, S.; DIAZ J.; SCIARA, A.A.; MARTINEZ P.; ARRANZ, S.E.

Santiago de Compostela

Simposio; INTERNATIONAL SYMPOSIUM ON GENETICS IN AQUACULTURE XII; 2015

ISGA

The pacú (Piaractus mesopotamicus) has become the most important fish in aquaculture in Argentina and is one of the most cultivated fish in Brazil and other South American countries. Although the pacú is the focus of major aquaculture efforts, appropriate parentage tools have not yet been developed for this species and little information is available about genetic diversity and structure of wild and cultured populations. In this study eighteen marker loci were standardized and tested for utility to perform parentage analysis in P. mesopotamicus. Markers were tested in three populations from Paraná and Paraguay Rivers from Argentina and Brazil. In addition families of pacú reared in an isolated environment were used to evaluate the usefulness of analyzed loci (Mendelian proportions, null alleles, genotyping errors) using a a Mendelian exclusion approach. Both probabilities EXCL1 and EXCL2 were obtained for different groups of loci to find the minimum number of loci required for a consistent parentage evaluation. Based on genotyping accuracy from family data, and genetic diversity and frequency of null alleles estimated from wild populations (n=79), a set of eleven markers was initially selected. The theoretical exclusion probabilities for this set of markers were EXCL1=0.9692 and EXCL2=.0.998. A final selected group of eight microsatellites was decided, theoretical exclusion probabilities values got slightly reduced to EXCL1= 0.9658 and EXCL2= 0.997. According to the ML analysis performed with Cervus it was expected to achieved 98% assignments at a single family with these eight markers. The microsatellite tool was evaluated for relatedness estimation using the actual family groups obtained in captivity with known kinship relationships. The estimated classification was contrasted against the true family data. Results from this work are relevant for the genetic management of P. mesopotamicus in captivity and to broodstock organization. The set of loci microsatellites selected prove to be helpful for solving unknown parentage in captive progenies and could be used for exploratory relatedness estimation among broodstock individuals with unknown relationships for stock organization.